Ref: S1-RS-MDA-52-7440

MPC Nom: DI-MPC-PB

Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Sentinel-1 Product Definition

Prepared By: Matthieu Bourbigot,

Harald Johnsen, Riccardo Piantanida

Checked By: Guillaume Hajduch

Quality Assurance: Julie Poullaouec

Project Manager: Guillaume Hajduch

(signature / date)

Document Number: S1-RS-MDA-52-7440

S-1 MPC Nomenclature: DI-MPC-PB
S-1 MPC Reference: MPC-0239

ESA Unclassified – For Official Use

 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

CHANGE RECORD

From issue 1.0 to 2.5, the Sentinel-1 Product Definition was maintained by a consortium led by
MDA under the reference S1-RS-MDA-52-7440.
The S-1 IPF and associated documentation is then maintained by the S-1 Mission Performance
Center. From the issue 2.6 the Sentinel-1 Product Definition is maintained by The S-1 Mission
Performance Center which is a consortium led by CLS.

ISSUE DATE PAGE(S) DESCRIPTION

1/0 Oct. 27, 2008 All First Issue
1/1 Jan. 16, 2009 All First Issue, First Revision.
Updated for major SRR RIDs:
SRR-002: Added S1-TN-ARE-PL-0007 as
applicable document
SRR-008: Corrected EW and WV mode definition
in Table 3-1
SRR-010: Reorganized Sections 3.2 and 3.3
SRR-011: Added Tables 4-1 and 4-3 as product tree
SRR-013: Described applications for all L1 product
types
SRR-014: Added annotation product description
SRR-016: Clarified term “derived” in section 4
SRR-023: Improved SLC IW product description in
section 4.1.2
SRR-029: Corrected GRD product description in
section 4.2
SRR-034: Corrected GCD/ORD product description
in sections 4.3 and 4.4
SRR-035: Clarified approach for generating
GCD/ORD products from GRD products.
SRR-039: Attached spreadsheet with product
characteristics calculation
SRR-041: Added missing product characteristics in
section 5.
SRR-042/SRR-396: Added range DTAR graphs and
clarified bits per pixel definition.
SRR-045/SRR-062: Added oversampling

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 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

ISSUE DATE PAGE(S) DESCRIPTION

calculation to spreadsheet.
SRR-050: Separated GRD/GCD/ORD product
characteristics tables. Added sub-type with large
ENL.
SRR-054: Added graph plotting incidence angle vs
orbit position.
SRR-066: Removed ENL options leading to non-
squared resolutions for IW/EW.
SRR-070: Clarified DEM used and DEM accuracy
impact on ORD product characteristics.
SRR-393: Removed Figure 4-1 image
SRR-398: Clarified number of bits per pixel for SLC
products
SRR-400: Added reference to S1-TN-SLR-SY-0003
for location accuracy details
SRR-404: Removed sentence about products
satisfying Nyquist criterion.
SRR-406: Changed geoid to ellipsoid in definition
of absolute location accuracy in section A2.9
SRR-462: Clarified that the application of the
scaling LUT is optional and configurable.
Updated for medium and minor SRR RIDs:
SRR-003, SRR-004, SRR-006,
SRR-007, SRR-009, SRR-012,
SRR-015, SRR-017, SRR-018,
SRR-019, SRR-020, SRR-021,
SRR-022, SRR-024, SRR-026,
SRR-027, SRR-030, SRR-031,
SRR-032, SRR-033, SRR-036,
SRR-037, SRR-038, SRR-040,
SRR-043, SRR-044, SRR-046,
SRR-047, SRR-048, SRR-049,
SRR-051, SRR-052,SRR-053,
SRR-055, SRR-056, SRR-057,
SRR-058, SRR-059, SRR-060,
SRR-063, SRR-064,SRR-067,

ESA Unclassified – For Official Use

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 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

ISSUE DATE PAGE(S) DESCRIPTION

SRR-068,SRR-071, SRR-072,
SRR-073, SRR-074, SRR-075,
SRR-076, SRR-078 SRR-391,
SRR-394, SRR-395, SRR-399,
SRR-403, SRR-405, SRR-444,
SRR-461.
2/0 June 24, 2009 All Second Issue.
Added L2 OSW and OWI product definitions.
Added L1 WV BRW product definition.
Updated GRD product definition for new resolution
classes.
Updated for major SRR RID:
SRR-014: Added annotation products.
Updated for medium and minor SRR RIDs:
SRR-017, SRR-048, SRR-074.
Updated for medium and minor Post-SRR
RIDs:PostSRR-1, PostSRR-2, PostSRR-3,
PostSRR-4, PostSRR-5, PostSRR-7,
PostSRR-8, PostSRR-9, PostSRR-10,
PostSRR-12, PostSRR-13, PostSRR-14,
PostSRR-15, PostSRR-16, PostSRR-17,
PostSRR-20, PostSRR-21, PostSRR-22,
PostSRR-23.
2/1 July 16, 2010 All Second Issue, First Revision.
Updated for Change Request #2:
Removed GEC/GTC content and added slicing
section.

Updated for major PDR L1 RIDs:

PD-1: Detailed change record for versions released
after SRR.
PD-5: Updated BRW Product characteristics.
PD-6: Added TBC for GRD resolution class used as
basis for BRW Product.

ESA Unclassified – For Official Use

(iv)
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

ISSUE DATE PAGE(S) DESCRIPTION

PD-8: Added complete product tree (L1 and L2).
PD-9, PD-11: Revised L2 product definition tables.
PD-12, PD-13: Added note that all L2 auxiliary files
come from the PDGS or external sources.
PD-14: Added L2 characteristics definition to
Appendix A in line with product definition tables.

Updated for medium and minor PDR L1 RIDs:

PD-2, PD-3, PD-4, PD-7, PD-10, PD-15, PD-16,
PD-21.

ESA Unclassified – For Official Use

(v)
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

ISSUE DATE PAGE(S) DESCRIPTION

2/2 Oct. 27, 2010 Second Issue, Second Revision.

Updated for major PDR L2 / Delta PDR L1 RIDs:

S1IPFPDR-161: Removed concatenated L1 products
Section 6.3
from list of possible inputs to L2 Processor.
S1IPFPDR-180: Clarified that annotation products
Section 5.4 for L2 products are based on the internal L1 SLC
product used for L2 processing.

Section 6.1 S1IPFPDR-182: OWI algorithm input is a GRD

product.
S1IPFPDR-190: Added reference to Product
Specification for L1 product concatenation strategy.
Section 5.5 Mentioned blackfill in L1 imagery due to SWST
changes and explained that its amount varies with
the segment length.
S1IPFPDR-325: Updated name of reference
Section 2.2 document “Mission Requirements Document for the
European Radar Observatory Sentinel-1”.
Updated for medium and minor PDR L2 / Delta
PDR L1 RIDs:
S1IPFPDR-160, S1IPFPDR-162, S1IPFPDR-163,
S1IPFPDR-178, S1IPFPDR-179, S1IPFPDR-181,
S1IPFPDR-183, S1IPFPDR-185, S1IPFPDR-187,
S1IPFPDR-188, S1IPFPDR-189, S1IPFPDR-301,
S1IPFPDR-302, S1IPFPDR-303, S1IPFPDR-304,
S1IPFPDR-305, S1IPFPDR-306, S1IPFPDR-307,
S1IPFPDR-308, S1IPFPDR-309 (except point 2),
S1IPFPDR-329, S1IPFPDR-330, S1IPFPDR-332.
Updated for PDR L2 actions:
PDRL2-A8: Clarified that OSW/OWI/RVL grids are
Section 8 in ground range.

Section 8 PDRL2-A10: Updated L2 product volumes to match

Product Specification release 2/1 and to match L1
product lengths used in section 7.

ESA Unclassified – For Official Use

(vi)
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

ISSUE DATE PAGE(S) DESCRIPTION

2/3 Mar. 21, 2011 Second Issue, Third Revision
Sections 5.1 Updated L1 product characteristics in line with
and 7 version 1/5 of GMES Sentinel-1 SAR Performance
Analysis document.
Section 7 Added Quick-Look characteristics.
All Removed browse products (descoped).
All Removed auxiliary Doppler calibration file.
All Removed auxiliary bathymetry and coast line files,
which are now internal to the IPF.
Updated for major Delta PDR L2 RIDs:
Section 9.1 S1IPFDPDRL2-42: Clarified digital elevation
models supported by the IPF.
Updated for minor Delta PDR L2 RIDs:
Section 10 S1IPFDPDRL2-41
2/4 Aug. 22, 2012 Second Issue, Fourth Revision
Sections Updated TOP SLC azimuth pixel spacing (SENIPF-
7.2.1, 7.3.1 5152)
Section 7.3 Updated EW ground coverage (SENIPF-5134)
Table 5-1, Updated ENL for all GRD products (SENIPF-5107)
Section 7

Updated for minor CDR RIDs:

IPFCDR-1, IPFCDR-2, IPFCDR-5
IPFCDR-3: changed RID resolution to remove the
OWI component from the WV OCN product, and to
mention that the wind information is present in the
OSW component.
2/5 Mar. 28, 2014 Second Issue, Fifth Revision
Section Update OSW size from 4 to 5 or 6 range cells
8.1.1 (SENIPF-5357)
Sections 7.2 Update the TOPS antenna steering rates and the
and 7.3, affected product characteristics. (SENIPF-5666)
Appendix C

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(vii)
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

ISSUE DATE PAGE(S) DESCRIPTION

2/6 June 18, 2014 Table 8-1, Changed parameters values, descriptions (related to
Table 8-2, MPCS-430, MPCS-543, IPF-3)
Table 8-3,
Table 8-4
Table 8-1, Deleted Doppler Spectral reference (related to
Table 8-2, MPCS-507, MPCS-533, IPF-3)
Table 8-3,
Table 8-4
A 2.2.4 Deleted Doppler Spectral Width section (related to
MPCS-507, MPCS-533, IPF-3)
2/7 March 25, 2016 Update of the L2 Product Definition for OCN
products
Table 8-1 Main Product characteristics for SM OCN: OSW
specific (Spectral Grid Resolution) and RVL
Specific (RVL Spatial Resolution and Grid
Dimension)
Product performance parameters (partition number)
Processing parameters – OSW specific (Azimuth
Look Bandwidth and Number of pixels used in
spectral Estimation [range, azimuth])
Data Size & Volume (number of Lines in Spectra
and of Pixels per Line)
Update of Notes in the table
Table 8-2 Main Product characteristics for IW OCN: RVL
Specific (RVL Spatial Resolution and Grid
Dimension)
Update of Notes in the table
Table 8-3 Main Product characteristics for EW OCN: RVL
Specific (RVL Spatial Resolution and Grid
Dimension)
Update of Notes in the table
Table 8-4 Main Product characteristics: OSW specific
Product performance parameters (partition number)
Processing parameters – OSW specific
Data Size & Volume
Update of Notes in the table
Appendix New section: A.2.4: Radial surface velocity

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(viii)
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

TABLE OF CONTENTS

1 INTRODUCTION.......................................................................................................... 1-1
1.1 Purpose................................................................................................................. 1-1
1.2 Scope .................................................................................................................... 1-1
1.3 Document Structure ............................................................................................. 1-1

2 DOCUMENTS................................................................................................................ 2-1
2.1 Applicable Documents ......................................................................................... 2-1
2.2 Reference Documents .......................................................................................... 2-1

3 SENTINEL-1 MISSION AND SAR SYSTEM OVERVIEW .................................... 3-1

3.1 Mission Overview ................................................................................................ 3-1
3.2 Sentinel-1 Main Payload and Platform Characteristics ....................................... 3-1
3.2.1 Sentinel-1 Acquisition Modes Overview ............................................. 3-2
3.2.2 SAR Instrument Polarisation Capabilities ........................................... 3-3
3.2.3 Attitude Steering Capabilities .............................................................. 3-4
3.2.3.1 Zero-Doppler Attitude Steering ............................................ 3-4
3.2.3.2 Roll Steering ......................................................................... 3-5
3.3 Sentinel-1 Acquisition Modes ............................................................................. 3-7
3.3.1 Stripmap Mode (SM) ........................................................................... 3-7
3.3.2 Interferometric Wide Swath Mode (IW) .............................................. 3-8
3.3.3 Extra-Wide Swath Mode (EW) ............................................................ 3-9
3.3.4 Wave Mode (WV) .............................................................................. 3-10

4 SENTINEL-1 PRODUCT FAMILY TREE ................................................................ 4-1

5 LEVEL 1 PRODUCTS OVERVIEW .......................................................................... 5-1

5.1 Products Summary ............................................................................................... 5-1
5.2 Product Type Descriptions................................................................................... 5-3
5.2.1 Slant Range, Single-Look, Complex Products (SLC) .......................... 5-3
5.2.1.1 SM SLC Product ................................................................... 5-4
5.2.1.2 IW SLC Product ................................................................... 5-4
5.2.1.3 EW SLC Product .................................................................. 5-4
5.2.1.4 WV SLC Product .................................................................. 5-5
5.2.2 Ground Range, Multi-Look, Detected Products (GRD) ...................... 5-5
5.3 Annotation Products ............................................................................................ 5-5
5.4 Slicing Impact on L1 Products............................................................................. 5-6
5.5 Radiometric Corrections ...................................................................................... 5-8
5.5.1 Standard Corrections ............................................................................ 5-8
5.5.2 Thermal Noise Removal....................................................................... 5-8
5.5.3 Application-Specific Output Image Scaling ........................................ 5-9
5.6 Applications for Level 1 Products ....................................................................... 5-9

6 LEVEL 2 PRODUCTS OVERVIEW .......................................................................... 6-1

6.1 Products Summary ............................................................................................... 6-1
6.2 Product Type Descriptions................................................................................... 6-2

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 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

6.2.1 Ocean Products (OCN)......................................................................... 6-2

6.2.1.1 Ocean Swell Spectra Component (OSW) ............................. 6-2
6.2.1.2 Ocean Wind Field Component (OWI) .................................. 6-3
6.2.1.3 Radial Surface Velocity Component (RVL)......................... 6-3
6.3 Slicing Impact on L2 Products............................................................................. 6-4
6.4 Applications for L2 OCN Products ..................................................................... 6-5
6.4.1 OSW Component ................................................................................. 6-5
6.4.1.1 Applications .......................................................................... 6-5
6.4.1.2 GMES services ..................................................................... 6-6
6.4.1.3 Basic User Requirements ...................................................... 6-6
6.4.2 OWI Component .................................................................................. 6-7
6.4.2.1 Applications .......................................................................... 6-7
6.4.2.2 GMES Services ..................................................................... 6-7
6.4.3 RVL Component .................................................................................. 6-8

7 LEVEL 1 PRODUCTS DEFINITION ......................................................................... 7-1

7.1 Stripmap L1 Products Definition ......................................................................... 7-2
7.1.1 Stripmap SLC Product Definition ........................................................ 7-2
7.1.2 Stripmap GRD Products Definition ..................................................... 7-3
7.2 Interferometric Wide Swath L1 Products Definition ........................................... 7-8
7.2.1 Interferometric Wide Swath SLC Product Definition .......................... 7-8
7.2.2 Interferometric Wide Swath GRD Products Definition ..................... 7-10
7.3 Extra Wide Swath L1 Products Definition ........................................................ 7-13
7.3.1 Extra Wide Swath SLC Product Definition ....................................... 7-13
7.3.2 Extra Wide Swath GRD Products Definition ..................................... 7-14
7.4 Wave L1 Products Definition ............................................................................ 7-18
7.4.1 Wave SLC Product Definition ........................................................... 7-18
7.4.2 Wave GRD Product Definition .......................................................... 7-19

8 LEVEL 2 PRODUCTS DEFINITION ......................................................................... 8-1

8.1 Stripmap L2 Products Definition ......................................................................... 8-2
8.1.1 Stripmap OCN Product Definition ....................................................... 8-2
8.2 Interferometric Wide Swath L2 Products Definition ........................................... 8-4
8.2.1 Interferometric Wide Swath OCN Product Definition ......................... 8-4
8.3 Extra Wide Swath L2 Products Definition .......................................................... 8-5
8.3.1 Extra Wide Swath OCN Product Definition ........................................ 8-5
8.4 Wave L2 Products Definition .............................................................................. 8-6
8.4.1 Wave OCN Product Definition ............................................................ 8-6

9 AUXILIARY DATA FOR L1 PROCESSING ............................................................ 9-1

9.1 Digital Elevation Model (DEM) .......................................................................... 9-1
9.2 L1 Processor Parameters ...................................................................................... 9-2
9.3 Calibration Data ................................................................................................... 9-2
9.4 Instrument Parameters ......................................................................................... 9-2
9.5 Orbit and Attitude Information ............................................................................ 9-2

10 AUXILIARY DATA FOR L2 PROCESSING .......................................................... 10-1

10.1 ECMWF Atmospheric Model ............................................................................ 10-1

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 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

10.2 Simulated Cross Spectra Data............................................................................ 10-1

10.3 Sea Ice Data ....................................................................................................... 10-2
10.4 Wavewatch3 Stokes Drift .................................................................................. 10-2
10.5 Excitation Coefficients Error Matrix ................................................................. 10-2
10.6 L2 Processor Parameters .................................................................................... 10-3

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 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

LIST OF FIGURES

Figure 3-1 Sentinel-1 Acquisition Modes .................................................................................. 3-3

Figure 3-2 Roll steering Variation of the Mechanical Off-nadir Angle along the Orbit ........... 3-6
Figure 3-3 TOPSAR Imaging Mode .......................................................................................... 3-8
Figure 4-1 Sentinel-1 Product Family Tree ............................................................................... 4-1
Figure 5-1 Data splitting for slicing scenario ............................................................................ 5-7
Figure B-1 Variation of the Near Range Incidence Angle along the Orbit for SM Mode ........B-2
Figure B-2 Variation of the Far Range Incidence Angle along the Orbit for SM Mode ...........B-2
Figure B-3 Ground Range Resolution of the SM_SLC Product at Minimum Altitude ............B-3
Figure B-4 Ground Range Resolution of the SM_SLC Product at Maximum Altitude ............B-3
Figure B-5 Ground Range Resolution of the SM_GRD_FR Product at Minimum
Altitude ................................................................................................................B-4
Figure B-6 Ground Range Resolution of the SM_GRD_FR Product at Maximum
Altitude ................................................................................................................B-4
Figure B-7 Ground Range Resolution of the SM_GRD_HR Product at Minimum
Altitude ................................................................................................................B-5
Figure B-8 Ground Range Resolution of the SM_GRD_HR Product at Maximum
Altitude ................................................................................................................B-5
Figure B-9 Ground Range Resolution of the SM_GRD_MR Product at Minimum
Altitude ................................................................................................................B-6
Figure B-10 Ground Range Resolution of the SM_GRD_MR Product at Maximum
Altitude ................................................................................................................B-6
Figure B-11 Range-DTAR Performance of the SM_SLC Product at Minimum Altitude ........B-7
Figure B-12 Range-DTAR Performance of the SM_SLC Product at Maximum Altitude ........B-7
Figure B-13 NESZ Performance of the SM_SLC Product at Minimum Altitude .....................B-8
Figure B-14 NESZ Performance of the SM_SLC Product at Maximum Altitude ....................B-8
Figure B-15 Variation of the Near Range Incidence Angle along the Orbit for IW Mode .......B-9
Figure B-16 Variation of the Far Range Incidence Angle along the Orbit for IW Mode .........B-9
Figure B-17 Ground Range Resolution of the IW_SLC Product at Minimum Altitude .........B-10
Figure B-18 Ground Range Resolution of the IW_SLC Product at Maximum Altitude.........B-10
Figure B-19 Ground Range Resolution of the IW_GRD_HR Product at Minimum
Altitude ..............................................................................................................B-11
Figure B-20 Ground Range Resolution of the IW_GRD_HR Product at Maximum
Altitude ..............................................................................................................B-11
Figure B-21 Ground Range Resolution of the IW_GRD_MR Product at Minimum
Altitude ..............................................................................................................B-12
Figure B-22 Ground Range Resolution of the IW_GRD_MR Product at Maximum
Altitude ..............................................................................................................B-12
Figure B-23 Range DTAR Performance of the IW_SLC Product at Minimum Altitude .......B-13
Figure B-24 Range DTAR Performance of the IW_SLC Product at Maximum Altitude .......B-13
Figure B-25 NESZ Performance of the IW_SLC Product at Minimum Altitude....................B-14
Figure B-26 NESZ Performance of the IW_SLC Product at Maximum Altitude ...................B-14

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 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Figure B-27 Variation of the Near Range Incidence Angle along the Orbit for EW Mode ....B-15
Figure B-28 Variation of the Far Range Incidence Angle along the Orbit for EW Mode ......B-15
Figure B-29 Ground Range Resolution of the EW_SLC Product at Minimum Altitude ........B-16
Figure B-30 Ground Range Resolution of the EW_SLC Product at Maximum Altitude .......B-16
Figure B-31 Ground Range Resolution of the EW_GRD_HR Product at Minimum
Altitude ..............................................................................................................B-17
Figure B-32 Ground Range Resolution of the EW_GRD_HR Product at Maximum
Altitude ..............................................................................................................B-17
Figure B-33 Ground Range Resolution of the EW_GRD_MR Product at Minimum
Altitude ..............................................................................................................B-18
Figure B-34 Ground Range Resolution of the EW_GRD_MR Product at Maximum
Altitude ..............................................................................................................B-18
Figure B-35 Range-DTAR Performance of the EW_SLC Product at Minimum Altitude ......B-19
Figure B-36 Range-DTAR Performance of the EW_SLC Product at Maximum Altitude .....B-19
Figure B-37 NESZ Performance of the EW_SLC Product at Minimum Altitude ..................B-20
Figure B-38 NESZ Performance of the EW_SLC Product at Maximum Altitude ..................B-20
Figure B-39 Variation of the Near Range Incidence Angle along the Orbit for WV Mode ...B-21
Figure B-40 Variation of the Far Range Incidence Angle along the Orbit for WV Mode ......B-21
Figure B-41 Ground Range Resolution of the WV_SLC Product at Minimum Altitude ........B-22
Figure B-42 Ground Range Resolution of the WV_SLC Product at Maximum Altitude .......B-22
Figure B-43 Ground Range Resolution of the WV_GRD_MR Product at Minimum
Altitude ..............................................................................................................B-23
Figure B-44 Ground Range Resolution of the WV_GRD_MR Product at Maximum
Altitude ..............................................................................................................B-23
Figure B-45 Range DTAR Performance of the WV_SLC Product at Minimum Altitude ......B-24
Figure B-46 Range DTAR Performance of the WV_SLC Product at Maximum Altitude .....B-24
Figure B-47 NESZ Performance of the WV_SLC Product at Minimum Altitude ..................B-25
Figure B-48 NESZ Performance of the WV_SLC Product at Maximum Altitude .................B-25
Figure D-1 Equivalent Number of Looks ................................................................................. D-2

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 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

LIST OF TABLES

Table 3-1 Sentinel-1 System Parameters ................................................................................... 3-1

Table 3-2 Sentinel-1 SM Mode Characteristics......................................................................... 3-7
Table 3-3 Incidence and Off-Nadir Angles for Stripmap Beams .............................................. 3-7
Table 3-4 Sentinel-1 IW Mode Characteristics ......................................................................... 3-9
Table 3-5 Incidence and Off-Nadir Angles for Interferometric Wide Swath Beams ................ 3-9
Table 3-6 Sentinel-1 EW Mode Characteristics ...................................................................... 3-10
Table 3-7 Incidence and Off-Nadir Angles for Extra Wide Swath Beams.............................. 3-10
Table 3-8 Sentinel-1 WV Mode Characteristics ...................................................................... 3-11
Table 3-9 Incidence and Off-Nadir Angles for Wave Mode Beams ....................................... 3-11
Table 5-1 Level 1 Product Family Summary ............................................................................. 5-2
Table 5-2 Sentinel-1 Level 1 Product Types ............................................................................. 5-3
Table 5-3 Sentinel-1 Applications ........................................................................................... 5-10
Table 5-4 Mapping of Applications to Modes and Product Types .......................................... 5-12
Table 6-1 Level 2 Product Family Summary ............................................................................. 6-1
Table 7-1 Stripmap SLC Product............................................................................................... 7-2
Table 7-2 Stripmap GRD FR Product ........................................................................................ 7-3
Table 7-3 Stripmap GRD HR Product ....................................................................................... 7-5
Table 7-4 Stripmap GRD MR Product ...................................................................................... 7-6
Table 7-5 Interferometric Wide Swath SLC Product ................................................................ 7-8
Table 7-6 Interferometric Wide Swath GRD HR Product ....................................................... 7-10
Table 7-7 Interferometric Wide Swath GRD MR Products..................................................... 7-11
Table 7-8 Extra Wide Swath SLC Product .............................................................................. 7-13
Table 7-9 Extra Wide Swath GRD HR Product ...................................................................... 7-14
Table 7-10 Extra Wide Swath GRD MR Product .................................................................... 7-16
Table 7-11 Wave SLC Product ................................................................................................ 7-18
Table 7-12 Wave GRD MR Product ........................................................................................ 7-19
Table 8-1 Stripmap OCN Product.............................................................................................. 8-2
Table 8-2 Interferometric Wide Swath OCN Product ............................................................... 8-4
Table 8-3 Extra Wide Swath OCN Product ............................................................................... 8-5
Table 8-4 Wave OCN Product ................................................................................................... 8-6
Table A-1 Hamming Window Properties ................................................................................. A-7

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ACRONYMS AND ABBREVIATIONS

A/D Analog to Digital Converter

ACE Altimeter Corrected Elevations (Digital Elevation Model)
ADC A/D Converter
ASAR Advanced Synthetic Aperture Radar
BAQ Block Adaptive Quantization
CFI Customer-Furnished Information
CNR Clutter to Noise Ratio
dB Decibel(s)
DC Doppler centroid
DCE Doppler Centroid Estimation
DEM Digital Elevation Model
DLR Deutsches Zentrum für Luft- und Raumfahrt (German Aerospace Centre)
DTAR Distributed Target Ambiguity Ratio
DTED Digital Terrain Elevation Data
EADS European Aeronautic Defence and Space Company
ECMWF European Centre for Medium-Range Weather Forecasts
ECR Earth Centred Rotating (Coordinates)
EGM Extended Graphics Memory
ENL Equivalent Number of Looks
ENVISAT ENVIronmental SATellite
ERS European Remote Sensing Satellite
ESA European Space Agency
EW Extra Wide Swath Mode
FR Full Resolution
GETASSE Global Earth Topography And Sea Surface Elevation (Digital Elevation Model)
GHz Gigahertz
GLOBE Global Land One-km Base Elevation
GMES Global Monitoring for Environment and Security
GRD Ground Range, Multi-look, Detected
H Horizontal
Hz Hertz

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HH Horizontal polarisation on transmit, Horizontal polarisation on receive

HR High Resolution
HV Horizontal polarisation on transmit, Vertical polarisation on receive
I and Q In-phase and Quadrature (channels)
ID Identifier
IFREMER Institut français de recherche pour l’exploitation de la mer (French Research
Institute for Exploitation of the Sea)
IPF Instrument Processing Facility
IRF Inpulse Response Function
IRW Impulse Response Width
ISLR Integrated Side Lobe Ratio
IW Interferometric Wide Swath Mode
L1 Level 1
L2 Level 2
LUT Look-up Table
km kilometre
kW kiloWatt
m metre
MB Megabyte - Unit of data volume equal to 220 bytes
MDA MacDonald, Dettwiler and Associates Ltd.
MERSEA Marine Environment and Security for the European Area
MHz MegaHertz
MR Medium Resolution
MSS Mean Sea Surface
MTF Modulation Transfer Function
N/A Not Applicable
NRCS Normalized Radar Cross-Section
NESZ Noise Equivalent Sigma Zero
Net CDF Network Common Data Forum
NGA National Geospatial-Intelligence Agency
NRT Near-Real-Time
NWP Numerical Weather Prediction
OCN Ocean (product)
OSI SAF Ocean and Sea Ice Satellite Application Facility

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OSV Orbit State Vectors

OSW Ocean Swell Spectra (component of OCN product)
OWI Ocean Wind Field (component of OCN product)
PDGS Payload Data Ground Segment
PDR Preliminary Design Review
PRF Pulse Repetition Frequency
PSLR Peak Side Lobe Ratio
PTAR Point Target Ambiguity Ratio
RF Radio Frequency
RFC Radio Frequency Compatibility
Rx Receive
RVL Radial Velocity (component of OCN product)
SAR Synthetic Aperture Radar
ScanSAR Scanning SAR
SLC Single-Look Complex
SM Stripmap Mode
SNR Signal to Noise Ratio
SOW Statement of Work
SRTM Shuttle Radar Topography Mission
SWST Sampling Window Start Time
T/R Transmit/Receive
TA Target Motion Analysis (module)
TBC To Be Confirmed
TBD To Be Determined
TOPSAR Terrain Observation with Progressive Scans SAR
TRIM Terrain Resource Information Management
Tx Transmit
UTC Universal Time Coordinated
V Vertical
VH Vertical polarisation on transmit, Horizontal polarisation on receive
VV Vertical polarisation on transmit, Vertical polarisation on receive
WGS84 World Geodetic System (1984)
WV Wave Mode

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1 INTRODUCTION

1.1 Purpose

In the frame of the Global Monitoring for Environment and Security (GMES)
program the European Space Agency (ESA) is undertaking the development of the
Sentinel-1, a European polar orbit satellite system for the continuation of Synthetic
Aperture Radar (SAR) operational applications in C-Band.

This document defines the complete Sentinel-1 product family generated by the
Sentinel-1 Instrument Processing Facility (IPF).The document also provides a brief
overview of the Sentinel-1 instrument, the operational modes and their characteristic
parameters, and the auxiliary data used for the generation of the products and the
applications which may use Sentinel-1 products.

1.2 Scope

This document includes:

• A description of the complete family of Sentinel-1 Level 1 and Level 2
products.
• A definition of the main system, processing and image quality characteristics
of each type of product (Note that the detailed derivation of these product
characteristics presented in Section 7 is included in Appendix C).
• The list of auxiliary data required for the generation of the proposed product
family.

The scope of this document is to describe products generated by the Sentinel-1 IPF.
The Level 0 products (i.e. the products that contain the acquired raw data) used to
produce the Level 1 products presented in this document are described in [R-8].

This document also focuses on the overall characteristics of the Sentinel-1 products.
Descriptions of the Sentinel-1 detailed product format and metadata contents are
provided in the Sentinel-1 Product Specification [R-6].

1.3 Document Structure

This document is structured as follows:

• Section 1 introduces the purpose, scope and structure of the document.
• Section 2 lists the applicable and reference documents.

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• Section 3 provides an overview of the Sentinel-1 instrument and acquisition

modes.
• Section 4 presents the Sentinel-1 product family tree.
• Section 5 introduces the L1 product types and provides an overview of the L1
product characteristics.
• Section 6 introduces the L2 product types and provides an overview of the L2
product characteristics.
• Section 7 contains the detailed L1 product definitions.
• Section 8 contains the detailed L2 product definitions.
• Section 9 contains an overview of the auxiliary data required for the
generation of the Sentinel-1 L1 product family.
• Section 10 contains an overview of the auxiliary data required for the
generation of the Sentinel-1 L2 product family.
• Appendix A provides definitions for the product characteristics and image
quality parameters used in the product definition tables.
• Appendix B contains graphs describing in more detail SAR performance of
the Sentinel-1 Level 1 products.
• Appendix C provides the detailed derivation of the product characteristics.
• Appendix D contains notes on some Product Definition related issues,
specifically the derivation of the (predicted) ENL and the Doppler Centroid
Estimation.

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2 DOCUMENTS

2.1 Applicable Documents

A-1 GMES-DFPR-EOPG-SW-07-00006 Sentinel-1 Product Definitions &

Instrument Processing Facility Development
Statement of Work, Issue/Revision 4/1, 23-05-
2008.

A-2 CCN No.2 Contract Change Notice N. 2, Changes in ESRIN

Contract No. 21722/08/I-LG, June 21, 2010.

A-3 S1-TN-ARE-PL-0001 GMES Sentinel-1 SAR Performance Analysis,

Version 1/5, Sep. 24, 2010, Aresys.

A-4 S1-RS-MDA-52-7452 Sentinel-1 IPF System Requirements Document,

Issue/Revision 2/2, Apr. 20, 2012. MacDonald
Dettwiler.

2.2 Reference Documents

R-1 ES-RS-ESA-SY-0007 Mission Requirements Document for the

European Radar Observatory Sentinel-1, Issue
1/4, ESA, July 11, 2005.

R-2 S1-RS-ESA-SY-0001 GMES Sentinel-1 System Requirements

Document, Issue 3/2, March 4, -2009, ESA.

R-3 S1-DD-ASD-PL-0001 Sentinel-1 SAR Instrument Technical Description,

Issue 5, Jan 25, 2010, EADS Astrium.

R-4 S1-RP-ASD-PL-0003 Instrument Calibration and Performance Analysis

and Budgets, Issue 2, Jul. 31, 2008, Astrium

R-5 Digital Processing of Synthetic Aperture Radar

Data, 2005 Artech House, Inc, Ian G. Cumming
and Frank H. Wong.

R-6 S1-RS-MDA-52-7441 Sentinel-1 Product Specification, Issue/Revision

2/5, August 2012. MacDonald Dettwiler.

R-7 Aerospace Avionics Systems, 1993 Academic

Press Inc. George M. Siouris.

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R-8 GM-ID-ACS-T8-0106 Sentinel-1 L0 Product Format Specification,

Issue/Revision 1/1, Apr. 20, 2010, ACS.

R-9 S1-RS-MDA-52-7443 Sentinel-1 IPF Auxiliary Product Specification,

Issue/Revision 2/5, August 2012. MacDonald
Dettwiler.

R-10 Rogers, W. E., “An investigation into sources of

error in low frequency energy5 predictions”, Tech.
Rep. Formal Report 7320-02-10035,
Oceanography division, Naval Research
Laboratory, Stennis Space Center, MS, 2002

R-11 Bidlot, J., S. Abdalla, and P. Janssen (2005), “A

revised formulation for ocean wave dissipation in
CY25R1”, Tech. Rep. Memorandum
R60.9/JB/0516, Research Department, ECMWF,
Reading, U. K.

R-12 Tolman, H. L. (2002), Validation of

WAVEWATCH-III version 1.15, Tech. Rep. 213,
NOAA/NWS/NCEP/MMAB.

R-13 Lotfi A., Lefevre M., Hauser D., Chapron B.,

Collard F., “The impact of using the upgraded
processing of ASAR Level 2 wave products in the
assimilation system”, Proc. Envisat Symposium,
22-26 April 2007, Montreux

R-14 Barstow S., Mørk G., Lønseth L., Schølberg P.,

Machado U., Athanassoulis G., Belibassakis K.,
Gerostathis Th., Spaan G., “WORLDWAVES –
Fusion of data from many sources in a user
friendly software package for timely calculation of
wave statistics in global coastal waters”, Proc. of
ISOPE 2003, May 2003, Hawaii

R-15 Ardhuin F., A. D. Jenkins, D. Hauser, A. Reiers,

B. Chapron, “Waves and Operational
Oceanography: Toward a Coherent Description of
the Upper Ocean”, Eos, Vol.86, No.4, 25 January
2005

R-16 Ryder P., “GMES Fast Track Marine Core

Services – Strategic Implementation Plan”, Final
Version, 24 April 2007

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3 SENTINEL-1 MISSION AND SAR SYSTEM OVERVIEW

3.1 Mission Overview

The Sentinel-1 SAR mission is part of the GMES system, which is designed to
provide an independent and operational information capacity to the European Union
to warrant environment and security policies and to support sustainable economic
growth. In particular, the mission will provide timely and high quality remote
sensing data to support monitoring the open ocean and the changes to marine and
coastal environmental conditions.

Sentinel-1 mission requirements are based on applications and services developed in

the frame of the GMES Service Element based on ERS and ENVISAT data and,
while taking full benefit of the heritage from these pre-cursor missions, are
optimised to enhance performance and operational capabilities.

The Sentinel-1 Ground Segment covers the complete supply chain required to
monitor and control the space and ground segment, to perform mission planning
according to defined operational scenarios, to acquire, process and distribute
Sentinel-1 products.

The mission objectives are defined in the Sentinel-1 Mission Requirements

Document [R-1].

3.2 Sentinel-1 Main Payload and Platform Characteristics

The Synthetic Aperture Radar (SAR) instrument is the main instrument carried by
the Sentinel-1 spacecraft. It operates in the C-Band with horizontal and vertical
polarisations. The instrument is based on a deployable planar phased array antenna
carrying Transmit/Receive Modules. The antenna features both azimuth and
elevation beam steering facilities, allowing SAR data acquisition in four different
modes (as described in Section 3.3), according to the needs of the particular
application. Table 3-1 summarises the characteristics of the platform and SAR
instrument. More details about the instrument can be found in [R-3].

Table 3-1 Sentinel-1 System Parameters

System Parameter Value

Radar Carrier Frequency 5.405 GHz

RF Peak Power 4.141 kW
Incidence Angle Range 20°-46°

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System Parameter Value

Look direction Right

Antenna Length 12.3 m
Azimuth Beam Width 0.23°
Azimuth Beam Steering Range -0.9° to +0.9°
Antenna width 0.82 m
Elevation Beam Width 3.43°
Elevation Beam Steering Range -13.0° to +12.3°
Maximum Range Bandwidth 100 MHz
Pulse Repetition Frequency (PRF) Range 1000 Hz - 3000 Hz
Polarisation Options Single (HH, VV)
Dual (HH+HV, VV+VH)
Attitude Steering Zero-Doppler Steering and
Roll Steering

Section 3.2.1 introduces the acquisition modes; Section 3.2.2 describes the
polarisation capabilities of the instrument and Section 3.2.3 presents the attitude
steering capabilities of the platform.

3.2.1 Sentinel-1 Acquisition Modes Overview

The Sentinel-1 SAR can be operated in one of four nominal acquisition modes (see
Figure 3-1):
1. Stripmap Mode (SM)
2. Interferometric Wide Swath Mode (IW)
3. Extra Wide Swath Mode (EW)
4. Wave Mode (WV)

The SAR instrument is capable of operating with duty cycles of 25 minutes per orbit
in the SM, IW or EW acquisition modes.

An overview of the Sentinel-1 acquisition modes is presented in Section 3.3.

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1
80
K

200 Km
m

2
360
3

4 100 Km

Figure 3-1 Sentinel-1 Acquisition Modes

3.2.2 SAR Instrument Polarisation Capabilities

The Sentinel-1 instrument is able to transmit horizontal (H) or vertical (V) linear
polarisations. The instrument is able to receive, on two separate receiving channels,
both H and V signals simultaneously.

Single co-polarisation products are obtained by operating the radar with the same (H
or V) polarisation on both transmit and receive. Dual-polarisation products are
obtained by operating the radar with one (H or V) polarisation on transmit and both
simultaneously on receive.

Dual-polarisation products are provided in the form of two images each

corresponding to a different polarisation channel (HH, VV, HV or VH). The images
have the same product characteristics and are co-registered.

For the SM, IW and EW modes, data can be acquired in either single co-polarisation
(HH or VV) or dual polarisation (HH+HV or VV+VH). For WV mode, only single
co-polarisation data acquisition is supported (HH or VV only).

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Complex-valued dual polarisation products contain the inter-channel phase

information which enables complex-valued polarimetry to be performed. Dual-
polarisation SAR allows the user to measure the polarisation properties of the terrain
in addition to the backscatter that can be measured from a single polarisation.
Ground targets have distinctive polarisation signatures in the same way that they
have distinctive spectral signatures. For example, volume scatterers have different
polarisation properties than surface scatterers. Dual-polarisation products therefore
provide improved classification of point targets and distributed target areas.

3.2.3 Attitude Steering Capabilities

The spacecraft attitude is the relative orientation of a spacecraft-fixed frame with

respect to a certain flight frame of reference. The attitude can be defined by a
sequence of three rotations described by the Euler angles, yaw, pitch and roll (for
attitude angles definition, see for example [R-7]; for definitions of Sentinel-1
reference frames see [R-2]).

During data acquisition activities, the attitude of the Sentinel-1 spacecraft is

controlled in order to satisfy specific purposes, ultimately leading to increased
image quality and efficient satellite operation activities.

The Sentinel-1 attitude steering has two main components, Zero-Doppler Attitude
Steering (which has both a yaw and a pitch component) and Roll Steering. These
modes of operation will be described in the next two sections.

3.2.3.1 Zero-Doppler Attitude Steering

The Sentinel-1 spacecraft nominal mode of operation is the Zero-Doppler Attitude
Steering Mode.

The Zero-Doppler Attitude Steering law - implemented for the first time on the
TerraSAR-X spacecraft - represents a significant improvement over the classical
yaw-steering law designed for previous SAR missions like ERS-1/2, ENVISAT or
RADARSAT-2.

Due to the Earth’s rotation, the Doppler centroid, which is the Doppler frequency
associated with the centre of the illuminating beam on the ground, varies over the
orbit; it also varies over range due to Sentinel-1’s orbit inclination being different
from 90º (see Sentinel-1 orbit characteristics in [R-2]). Uncompensated variations of
the Doppler centroid may cause significant, undesirable radiometric variations in the
image. For cases of large Doppler centroid errors, focusing and geo-location quality
may also be affected.

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Similar to the yaw-steering law, the zero-Doppler steering law is a technique aimed
at compensating the Doppler shift induced by Earth’s rotation. Unlike the yaw-
steering law, which is designed to reduce the Doppler centroid to zero at the mid
range of the swath, the Zero-Doppler Attitude Steering Law is designed to reduce
the Doppler centroid to a theoretical 0 Hz, independent of the range position of
interest. This is achieved by combining the yaw-steering with an additional pitch-
steering. In this way, residual errors are only due to pointing inaccuracy, orbit
variation errors, variations in terrain height or implementation approximations.

The Zero-Doppler Attitude Steering law has a number of notable advantages with
bearing on the Sentinel-1 Level 1 products and potential applications quality. The
low residual Doppler centroid and the reduced variation of the Doppler centroid
over range allow:
• More accurate Doppler centroid estimation and therefore more precise
azimuth antenna pattern compensation
• Potential reduction of scalloping in the images produced from ScanSAR-type
modes (IW and EW). Note that the Terrain Observation with Progressive
Scans SAR (TOPSAR) imaging technique already avoids scalloping,
independently of the Zero-Doppler Attitude Steering law.
• Optimized overlap of the azimuth spectra of SAR image pairs for cross-track
interferometry
• Reduced susceptibility to range dependent interferometric phase bias caused
by a misregistration between the interferometric images

3.2.3.2 Roll Steering

The Roll Steering Mode is a new type of attitude control implemented for the first
time on the Sentinel-1 spacecraft. The Roll Steering Mode is a continuous
manoeuvre around the orbit (similar to the yaw steering in azimuth) that
compensates for the altitude variations, in order to minimize the updates of the PRF
and sampling window position around the orbit. This allows the instrument to
operate with a small fixed set of antenna beams, and simplifies the instrument
operation significantly (see [R-3]).

The roll steering law defines the roll angle (or equivalently, the off-nadir angle of
pointing) of the antenna mechanical boresight versus time. The off-nadir angle is
defined as a linear function of the satellite altitude. This results in a variation around
the orbit of the off-nadir angle of up to approximately ± 0.8 degrees with respect to
the off-nadir angle at the reference altitude, which is 711.7 km (see Table 3-3, Table
3-5, Table 3-7 and Table 3-9 for angle ranges specific for each beam).

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Due to this variation, parameters dependent on the off-nadir angle (and implicitly on
the incidence angle) will also exhibit (small) variations around the orbit. In
particular, the ground range resolution will vary by a maximum of ± 5% with
respect to the reference incidence angle and around the orbit, maximum variation
taking place at near range (~ 19 degrees) (see also the ground resolution plots in
Appendix B). The ground range coverage is also affected by the incidence angle
variation, but only marginally.

Figure 3-2 shows the type of variation of the off-nadir angle along the orbit, versus
the orbit time and versus the altitude over the reference ellipsoid (this particular
example is for a predicted orbit of 1st January 2011). The top graph illustrates the
variation of the off-nadir angle with respect to orbit time while the bottom graph
illustrates the variation of the off-nadir angle with respect to orbit altitude.

Figure 3-2 Roll steering Variation of the Mechanical Off-nadir Angle along the Orbit

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3.3 Sentinel-1 Acquisition Modes

This section provides a brief description of each Sentinel-1 acquisition mode.

3.3.1 Stripmap Mode (SM)

The Sentinel-1 SM mode is a standard SAR stripmap imaging mode (as shown in
Figure 3-1), where the ground swath is illuminated with a continuous sequence of
pulses while the antenna beam is pointing to a fixed azimuth angle and an
approximately fixed off-nadir angle (The off-nadir angle is subject to small
variations according to the roll steering law, as described in Section 3.2.3.2). This
results in an image strip with continuous along-track image quality at an
approximately constant incidence angle. SM can operate with one of 6 predefined
elevation beams, each characterised by a different incidence angle coverage. The
main parameters characterising this mode are summarized in Table 3-2. Note that
the resolution values specified in the table correspond to the 1-look Ground Range
Multi-Look Detected (GRD) product approximate resolution (see Section 5.2.2 for
the GRD product definition).

Table 3-2 Sentinel-1 SM Mode Characteristics

Parameter Value

Minimum Ground Swath Width 80 km

Incidence Angle Range 18.3°-46.8°
Number of Elevation Beams 6
Azimuth resolution 5.0 m
Ground Range Resolution 5.0 m
Polarisation Options Single (HH or VV) or
Dual (HH+HV or VV+VH)

Table 3-3 provides the precise incidence and off-nadir angle ranges corresponding to
the minimum and maximum orbit height satellite positions, which are ~698 km and
respectively ~726 km. (Off-nadir angles - and implicitly incidence angles - vary
with position of the satellite in orbit according to the roll steering law as described
in Section 3.2.3.2.)

Table 3-3 Incidence and Off-Nadir Angles for Stripmap Beams

Beam S1 S2 S3 S4 S5 S6

Off Nadir
Minimum 17.93-23.53 21.00-26.33 26.18-30.99 30.87-35.15 35.07-38.85 37.53-41.01
Angles [°]
Orbit
Altitude Incidence
19.99-26.31 23.45-29.50 29.33-34.85 34.71-39.72 39.62-44.12 42.53-46.73
Angles [°]

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Beam S1 S2 S3 S4 S5 S6

Off Nadir 16.45-

Maximum 19.51-24.77 24.67-29.45 29.34-33.63 33.53-37.34 35.98-39.51
Angles [°] 21.96
Orbit
Altitude Incidence
18.32-24.55 21.78-27.76 27.64-33.13 33.00-38.02 37.89-42.43 40.79-45.04
Angles [°]

3.3.2 Interferometric Wide Swath Mode (IW)

The Sentinel-1 IW mode acquires data of wide swaths (composed of 3 sub-swaths),

at the expense of resolution, using the TOPSAR imaging technique. The TOPSAR
imaging is a form of ScanSAR imaging (the antenna beam is switched cyclically
among the three sub-swaths, as shown in Figure 3-1) where, for each burst, the beam
is electronically steered from backward to forward in the azimuth direction, as
shown in Figure 3-3. This leads to uniform NESZ and ambiguity levels within the
scan bursts, resulting in a higher quality image.

Figure 3-3 TOPSAR Imaging Mode

Another key feature of the IW mode is that bursts are synchronised from pass to
pass to ensure the alignment of interferometric pairs.

The IW mode is a TOPSAR single sweep mode; the radar beam switching has been
chosen to provide one azimuth look per beam for all points. Table 3-4 presents the
main parameters characterising this mode. Note that the resolution values specified
in the table correspond to the 1-look Ground Range Multi-Look Detected (GRD)
product approximate resolution (see Section 5.2.2 for the GRD product definition).

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Table 3-4 Sentinel-1 IW Mode Characteristics

Parameter Value

Minimum Ground Swath Width 250 km

Incidence Angle Range 29.1°-46.0°
Number of Sub-swath 3
Azimuth Steering Angle ± 0.6°
Azimuth Resolution 20 m
Ground Range Resolution 5m
Polarisation Options Single (HH or VV) or
Dual (HH+HV or VV+VH)

Table 3-5 provides the precise incidence and off-nadir angle ranges corresponding to
the minimum and maximum orbit height satellite positions, which are ~698 km and
respectively ~726 km. (Off-nadir angles - and implicitly incidence angles - vary
with position of the satellite in orbit according to the roll steering law as described
in Section 3.2.3.2.).

Table 3-5 Incidence and Off-Nadir Angles for Interferometric Wide Swath Beams

Beam IW1 IW2 IW3

Minimum Off Nadir Angles [°] 27.53-32.48 32.38-36.96 36.87-40.40

Orbit Altitude Incidence Angles [°] 30.86-36.59 36.47-41.85 41.75-46.00

Maximum Off Nadir Angles [°] 26.00-30.96 30.86-35.43 35.35-38.88

Orbit Altitude Incidence Angles [°] 29.16-34.89 34.77-40.15 40.04-44.28

3.3.3 Extra-Wide Swath Mode (EW)

The EW mode (as shown in Figure 3-1) also uses the TOPSAR imaging technique
(see Figure 3-3). The EW mode provides a very large swath coverage (obtained
from imaging 5 sub-swaths) at the expense of a further reduction in resolution.

As the IW mode, the EW mode is a TOPSAR single sweep mode. Table 3-6
presents the main parameters characterising this mode. Note that the resolution
values specified in the table correspond to the 1-look Ground Range Multi-Look
Detected (GRD) product approximate resolution (see Section 5.2.2 for the GRD
product definition).

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Table 3-6 Sentinel-1 EW Mode Characteristics

Parameter Value

Minimum Ground Swath Width 410 km

Incidence Angle Range 18.9°-47.0°
Number of Sub-swath 5
Azimuth Steering Angle ± 0.8°
Azimuth Resolution 40 m
Ground Range Resolution 20 m
Polarisation Options Single (HH or VV) or
Dual (HH+HV or VV+VH)

Table 3-7 provides the precise incidence and off-nadir angle ranges corresponding to
the minimum and maximum orbit height satellite positions, which are ~698 km and
respectively ~726 km. (Off-nadir angles - and implicitly incidence angles - vary
with position of the satellite in orbit according to the roll steering law as described
in Section 3.2.3.2).

Table 3-7 Incidence and Off-Nadir Angles for Extra Wide Swath Beams

Beam EW1 EW2 EW3 EW4 EW6

Off Nadir Angles

17.94-26.07 26.02-30.66 30.61-35.10 35.06-38.66 38.63-41.20
Minimum Orbit [°]
Altitude
Incidence Angles [°] 20.00-29.20 29.15-34.47 34.41-39.66 39.60-43.89 43.86-46.97

Off Nadir Angles

16.36-24.49 24.44-29.08 29.03-33.52 33.48-37.08 37.05-39.62
Maximum [°]
Orbit Altitude
Incidence Angles [°] 18.22-27.57 27.38-33.42 32.65-38.05 37.84-42.53 42.08-45.16

3.3.4 Wave Mode (WV)

The WV mode (as shown in Figure 3-1 acquires small stripmap scenes (also called
“vignettes”), situated at regular intervals of 100 km along track (between the centre
of consecutive vignettes), similar to the ERS and ENVISAT ASAR wave imaging
modes. This sub-sampling allows generating low data volume.

The vignettes are acquired in ‘leap frog’ mode, i.e. one vignette is acquired at a near
range incidence angle while the next vignette is acquired at a far range incidence
angle, as illustrated in Figure 3-1.

The WV mode, which allows sampling of low-volume data from vast areas, was
specifically designed for ocean applications (see Section 5.6 for examples of
applications).

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Table 3-8 presents the key Sentinel-1 WV mode characteristics. Note that the
resolution values specified in the table correspond to the 1-look Ground Range
Multi-Look Detected (GRD) product approximate resolution (see Section 5.2.2 for
the GRD product definition).

Table 3-8 Sentinel-1 WV Mode Characteristics

Parameter Value

Vignette ground coverage 20 km x 20 km

Along Track Distance between 100 km
Centre of Consecutive Vignettes
Incidence Angle Range 21.6 – 25.1 and 34.8 – 38.0
Number of elevation beams 2
Azimuth Resolution 5.0 m
Ground Range Resolution 5.0 m
Polarisation Options Single (HH or VV)

Table 3-9 provides the precise incidence and off-nadir angle ranges corresponding to
the minimum and maximum orbit height satellite positions, which are ~698 km and
respectively ~726 km. (Off-nadir angles - and implicitly incidence angles - vary
with position of the satellite in orbit according to the roll steering law as described
in Section 3.2.3.2).

Table 3-9 Incidence and Off-Nadir Angles for Wave Mode Beams

Beam WV1 WV2

Off Nadir Angles

21.03-22.40 32.56-33.62
Minimum [°]
Orbit Altitude Incidence Angles
23.47-25.03 36.67-37.92
[°]
Off Nadir Angles
19.43-20.79 30.96-32.02
Maximum [°]
Orbit Altitude Incidence Angles
21.68-23.22 34.88-36.13
[°]

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4 SENTINEL-1 PRODUCT FAMILY TREE

The Sentinel-1 product family tree is presented in Figure 4-1. The acronyms in this
figure are described in Sections 5.1 and 6.1 for Level 1 and Level 2 respectively.

Acquisition L1 Product Resolution L2 Product

Mode Type Class Type

SLC

FR

SM GRD HR

MR

OCN

SLC

IW HR
GRD
MR

OCN

SLC

EW HR
GRD
MR

OCN

SLC

WV GRD MR

OCN

Figure 4-1 Sentinel-1 Product Family Tree

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5 LEVEL 1 PRODUCTS OVERVIEW

This section presents an overview of the Sentinel-1 Level 1 products and their
properties. A detailed definition of each product in the family is provided in
Section 7.

Section 5.1 summarizes the Level 1 product family and the main properties of each
product in the family. Section 5.2 briefly describes each product type. Section 5.3
introduces the annotation products. Section 5.4 describes the slicing scenario and
how it impacts L1 products characteristics. Section 5.5 describes the radiometric
corrections applied by the IPF during processing. Finally, Section 5.6 describes
Sentinel-1 applications and presents a mapping of these applications to modes and
product types.

5.1 Products Summary

For the Sentinel-1 acquisition modes discussed in Section 3.3, the following types of
L1 products are defined:
a) Slant Range, Single-Look Complex (SLC)
b) Ground Range, Multi-Look, Detected (GRD)

The detected products can be further classified according to their resolution into:
• Full Resolution (FR) products
• High Resolution (HR) products
• Medium Resolution (MR) products

Resolution classes are characterised by the acquisition mode employed as well as by

the level of multi-looking performed during processing.

The SLC products, being single-look products, have the resolution largely
determined by the acquisition mode; therefore further classification according to
resolution class does not apply for SLC products.

The resolution classes are consistent between the modes in the sense that two
products of two different modes but in the same resolution class will have
approximately the same key properties (as reflected in Table 5-1).

Table 5-1 presents all the valid combinations of acquisition modes, product types
and resolution classes for the standard Level 1 products together with their main
properties.

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Table 5-1 Level 1 Product Family Summary

Pixel
Resolution 1, 2
Acq. Resolution Spacing 2 No. Looks
Product Type [Rng x Azi] 3 ENL4
Mode Class [Rng x Azi] [Rng x Azi]
[m]
[m]

1.7 x 4.3 to 1.5 x 3.6 to

SLC 1x1 1
3.6 x 4.9 3.1 x 4.1
SM FR 9x9 3.5 x 3.5 2x2 3.7
GRD
HR 23 x 23 10 x10 6x6 29.7
MR 84 x 84 40 x 40 22 x 22 398.4
2.7 x 22 to
SLC 2.3 x 14.1 1 1
3.5 x 22
IW
GRD HR 20 x 22 10 x 10 5x1 4.4
MR 88 x 87 40 x 40 22 x 5 81.8
7.9 x 43 to
SLC 5.9 x 19.9 1x1 1
15 x 43
EW
GRD HR 50 x 50 25 x 25 3x1 2.7
MR 93 x 87 40 x 40 6x2 10.7
2.0 x 4.8 and 1.7 x 4.1 and
SLC 1x1 1
WV 3.1 x 4.8 2.7 x 4.1
GRD MR 52 x 51 25 x 25 13 x 13 123.7

Notes:

(1) For GRD Products, the resolution corresponds to the mid range value at mid orbit altitude,
averaged over all swaths.
(2) For SLC SM/IW/EW products, the resolution and pixel spacing are provided from lowest to
highest incidence angle. For SLC WV products, the resolution and pixel spacing are provided for
beams WV1 and WV2.

(3) For SLC products, the range coordinate is in slant range. All the other products are in ground
range.

(4) For GRD IW/EW products, the equivalent number of looks corresponds to an average over all
swaths.

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5.2 Product Type Descriptions

The main distinguishing characteristics of the Sentinel-1 Level 1 product types are
the data type and the coordinate system of the image (see Table 5-2). Note that all
Sentinel-1 Level 1 products are geo-referenced. Also note that all Sentinel-1 Level 1
products are time tagged with the zero Doppler time at the centre of the swath and
that the geo-referencing is corrected for the azimuth bi-static bias by taking into
account the pulse travel time delta between the centre of the swath and the range of
each geo-referenced point.

Table 5-2 Sentinel-1 Level 1 Product Types

Mnemonic Data Type Coordinate System

SLC Complex Slant Range x Azimuth

GRD Detected Ground Range x Azimuth

Note that for products of any type generated from SM, IW or EW data, the focused
image can be as long as the complete acquisition segment/strip. To ensure the
homogeneity of the scene, SAR parameters that vary with the satellite position in
orbit (like azimuth FM rate, Doppler Centroid Frequency, terrain height) are
periodically updated to ensure the homogeneity of the scene. (See also in Section
5.5.1 the reference to the antenna elevation beam pattern correction.)

Similarly, products generated from WV data can contain any number of vignettes,
potentially up to an entire orbit’s worth.

Sections 5.2.1 and 5.2.2 give brief descriptions of each Sentinel-1 Level 1 product
type.

5.2.1 Slant Range, Single-Look, Complex Products (SLC)

SLC products are images in the slant range by azimuth imaging plane, in the image
plane of satellite data acquisition. Each image pixel is represented by a complex (I
and Q) magnitude value and therefore contains both amplitude and phase
information. The processing for all SLC products results in a single look in each
dimension using the full available signal bandwidth. The imagery is geo-referenced
using orbit and attitude data from the satellite. SLC images are produced in a zero
Doppler geometry. This convention is common with the standard slant range
products available from other SAR sensors e.g. ERS-1/2, ENVISAT/ASAR,
RADARSAT-1/2, TerraSAR-X.

In addition to the general SLC properties discussed above, some acquisition mode-
specific properties are discussed in the sections below.

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5.2.1.1 SM SLC Product

The SM SLC Products contain one image per polarisation channel (i.e. one or two
images).

The SM SLC image is sampled at the natural pixel spacing. This means, the pixel
spacing is determined, in azimuth by the pulse repetition frequency (PRF), and in
range by the radar range sampling frequency.

The detailed definition of the SM SLC product is provided in Section 7.1.1.

5.2.1.2 IW SLC Product

The IW SLC product contains one image per sub-swath, per polarisation channel,
for a total of three or six images. Each sub-swath image consists of a series of
bursts, where each burst was processed as a separate SLC image. The individually
focused complex burst images are included, in azimuth-time order, into a single sub-
swath image, with black-fill demarcation in between, similar to the ENVISAT
ASAR ScanSAR SLC product. This image format is described in further detail in
the Sentinel-1 Product Specification [R-6].

Due to the one natural azimuth look inherent in the data, the imaged ground area of
adjacent bursts will only marginally overlap in azimuth - just enough to provide
contiguous coverage of the ground.

Unlike SM and WV SLC products, which are sampled at the natural pixel spacing,
the images for all bursts in all sub-swaths of an IW SLC product are re-sampled to a
common pixel spacing grid in range and azimuth. The resampling to a common grid
eliminates the need of further interpolation in case, in later processing stages, the
bursts are merged to create a contiguous ground range, detected image (see Section
5.2.2).

The detailed definition of the IW SLC product is provided in Section 7.2.1.

5.2.1.3 EW SLC Product

The EW SLC products contain one image per sub-swath, per polarisation channel,
for a total of five or ten images.

Each TOPSAR EW burst in a sub-swath is processed as a separate SLC image, and

included in a sub-swath image exactly as in the IW case. Like the IW mode, EW is a
one natural azimuth look mode, and therefore the EW and IW images have similar
properties.

As for the IW SLC products, the images for all bursts in all sub-swaths of an EW
SLC product are re-sampled to a common pixel spacing grid in range and azimuth.

The detailed definition of the EW SLC product is provided in Section 7.3.1.

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5.2.1.4 WV SLC Product

WV acquisitions consist of several vignettes, with each vignette processed as a
separate image. Thus, each WV product contains multiple images, all corresponding
to the single-polarisation in which the data has been acquired (VV or HH).

As the SM SLC product, the WV SLC product is sampled at the natural pixel
spacing.

The detailed definition of the WV SLC product is provided in Section 7.4.1.

5.2.2 Ground Range, Multi-Look, Detected Products (GRD)

GRD products lie in the ground range by azimuth surface, with image coordinates
oriented along ground range and flight direction. The standard GRD products are
detected, multi-look products, with approximately square resolution cells and square
pixel spacing. Multi-looking is a processing property that results in images with
reduced speckle, but also with reduced resolution: the more looks the less speckle
noise and the lower the resolution (see also definitions A1.3.1 to A.1.3.5).

For each mode, a number of resolution classes are defined, as described in Section
5.1; the resolution, pixel spacing and multi-look characteristics of the standard GRD
products are provided in Table 5-1.

To convert from imaging slant range coordinates to ground range coordinates, a

slant to ground projection is performed onto an ellipsoid (typically the WGS84
ellipsoid) corrected using terrain height, which varies in azimuth and is constant in
range.

GRD images are produced in a zero Doppler geometry. The principle of generating
GRD products is the same for all acquisition modes. However, for the TOPSAR
modes, the multi-looking is performed on each burst individually, while for the SM
mode multi-looking is performed on entire blocks of azimuth data.

For the IW and EW GRD products, as opposed to the SLC products, all the bursts in
all sub-swaths are seamlessly merged to form a single, contiguous, ground range,
detected image. Therefore, the IW and EW GRD products, like the SM products,
contain one image per polarisation channel (i.e. either one or two images).

The definitions of the GRD products for the SM, IW, EW and WV acquisition
modes are provided in Sections 7.1.2, 7.2.2, 7.3.2 and 7.4.2 respectively.

5.3 Annotation Products

An annotation product is a product created from one of the standard products

described above. It is identical to the product it is based on, except that it does not

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include the full resolution image(s), but only the lower resolution quick-look
image(s) if there is one in the base product. If generated, the annotation product is
produced in addition to the original product. For L2 products, the annotation product
is based on the internal L1 SLC product used as input to the L2 Processor.

Annotation products are intended for PDGS internal quality assurance, calibration
and validation purposes only. They are not meant to be distributed to GMES
services end-users.

5.4 Slicing Impact on L1 Products

L1 products may be generated by the Sentinel-1 IPF using one of the following
processing options:
• Processing a L0 segment of data and generating a single L1 product that
covers the segment
• Dividing the L0 segment of data to process into multiple slices (where slices
are overlapping subsets, in the azimuth direction, of the full segment) and
processing each slice separately. These slices are processed such that the
multiple L1 slice products generated can be recombined into a single,
continuous L1 product after all the slices have been processed. The rationale
for the slicing scenario is to enable the processing of a segment of data in
parallel to increase the processor throughput for SM, IW and EW acquisition
modes.

Figure 5-1 depicts how the data is split in the slicing scenario, and how this affects
the extents of the L1 products generated by the IPF.

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Data take start time

Segment start time

Data take stop time

Segment stop time
Data Take

L0 Segment

L0 Slice #1

L0 Slice #2

L0 Slice #3

L0 Slice #4
Throaway

Throaway
L1 Segment Slice 1 Slice 2 Slice 3 Slice 4

Figure 5-1 Data splitting for slicing scenario

As a result of these two processing options, the L1 products generated by the IPF for
a given L0 segment of data may be either:
• An individual scene product, which is a single L1 product that covers the
complete L0 segment of data (non-slicing scenario); or
• A set of L1 slice products that collectively cover the same L0 segment of data
(slicing scenario before concatenation of all L1 slices was performed). These
L1 products are continuous in terms of coverage (no overlap or gap between
them) and in terms of radiometry and phase. As a result, it is possible to
assemble them into a single L1 product that covers the segment of data. The
assembly strategy for L1 slice products is described in [R-6].

L1 product characteristics described in Sections 5 and 7 are not affected by slicing

in the sense that an L1 individual scene product and a set of L1 slice products
generated from the same L0 segment of data have the same characteristics
(collectively for the L1 slice products).

The amount of blackfill at near and far range of the L1 imagery, due to SWST
changes, varies with the segment length. The longer the segment the more blackfill
is present, generally. As a result, a L1 slice product which is part of a longer
segment generally contains more blackfill than a non-slice product that covers the
same extent as the single slice.

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5.5 Radiometric Corrections

This section gives a brief description of the radiometric corrections performed by

the IPF. Section 5.5.1 lists the standard radiometric corrections applied to all Level 1
products. Sections 5.5.2 and Section 5.5.3 present the following additional
radiometric corrections: Thermal Noise Correction and Application-specific Output
Image Scaling.

5.5.1 Standard Corrections

The SAR processor incorporates several corrections designed to compensate for

variations in the radar sensor and its ability to provide repeatable measurements over
periods of time. The SAR processor also compensates for variations in signal
intensity due to either the antenna beam patterns or the propagation of spherical
electromagnetic waves. For all products, the following corrections are applied by
default during SAR processing:
• Raw signal I and Q channel bias correction
• Transmitted power and receiver (instrument) gain and other parameters and
offset corrections
• Antenna elevation beam pattern correction
• Antenna azimuth beam pattern correction
• Range spreading loss compensation
• Inter-channel (phase and gain) correction, applied to dual-polarisation
products. This correction is implicitly built into the extracted replicas, but it is
applied as a separate processing step when using the nominal coefficients.

Note that the radiometric homogeneity of long acquisition images can potentially be
affected by variations in the terrain height. To address this issue, the elevation beam
pattern correction accounts for terrain height variations in both range and azimuth
directions.

The azimuth antenna beam pattern removal accuracy depends on the accuracy of the
antenna beam pointing determination. As explained in Section 3.2.3.1, this precision
in the determination of the antenna beam pointing is greatly improved by the zero-
Doppler steering capability of the Sentinel-1 platform.

5.5.2 Thermal Noise Removal

Unlike quantization noise, thermal noise is independent of the signal power.

Consequently, as a result of the range varying radiometric corrections applied during
SAR processing, the thermal noise contribution is reshaped in a range varying
fashion, affecting in this way the quality of the image (especially in areas of low

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backscatter like calm seas, lakes etc ). The Sentinel-1 SAR processor provides the
capability to estimate and to remove the thermal noise contribution, improving in
this way the quality of the detected Level 1 images. This correction is applied only
to detected products. Thermal noise removal is optional and configurable. The
thermal noise is provided in the product annotations to give the user the possibility
to re-apply it to products where it was removed.

5.5.3 Application-Specific Output Image Scaling

The final step in producing an output image is the adjustment of the output scaling.
The application of this scaling is optional and configurable. The purpose of this
scaling is to:
• Optimize the radiometric scaling of the main feature of interest (while
optimizing the available dynamic range in the output product),
• Compensate for changes in the radar backscatter with changing incidence
angles (for the main feature of interest to the user).

To achieve these objectives, adequate Application Look-Up Tables (LUTs) are used
to apply a range dependent gain function (and possibly a fixed offset) to the
processed data prior to generation of the final image output.

The Application LUT applied depends on configuration parameters. Examples of

application LUTs include:
• Point Target Application LUTs - suited to applications involving scattering
from bright points targets. Typically these LUTs provide poor quantization
over area of very low backscatter.
• The Sea, Land, Mixed and Ice LUTs - suited to the thematic applications they
describe in which low backscatter features are expected. Typically, bright
targets will saturate. Values vary with incidence angle.
• General application LUT – typically very bright targets will be saturated.

The application-specific scaling that has been applied by the processor is reported in
the product annotations, hence the user has all the information necessary to convert
the pixel integer values back to the original digital numbers.

5.6 Applications for Level 1 Products

The Sentinel-1 products are defined to serve a number of activities within the GMES
Services Element. These activities, the specific information that can be extracted
from the SAR images, as well as the services that could exploit this information are
described in Table 5-3 (see also [R-1]).

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Table 5-3 Sentinel-1 Applications

Activities/
SAR-enabled Capability Objectives/Services
Applications

Monitoring the European • Oil-spill pollution detection • Gather prosecution evidence in case of
Marine Environment illegal discharges
• Ship detection
• Support effective survey aircraft
deployment and cleaning operations
• Monitor activities by flag state vessels
in third party waters
• Monitor major shipping routes to
detect illegal activities
Monitoring the Arctic • Perform ice type classification • Assess environmental impact of
Environment and Sea-Ice changes in extent and properties of the
• Perform sea-ice mapping
Zones Arctic ice
• Detect changes in Arctic sea ice
• support transport operations
extent
• Detect ice-infested areas along the
major transport routes
Monitoring and Assessing • High accuracy (up to millimetre-size) • provide a Pan-European ground
Land Surface-Motion detection of ground level motion hazard information service to
Risks displacements using interferometry facilitate saving lives, improving
safety and reducing economic loss
• In particular, detection of urban
subsidence, landslides and other • Regular measurements of subsidence
terrain displacement to be over all major urban areas
encountered in earthquake zones,
• Regular surveillance of transport
coastline zones and flood plains
infrastructure
Open Ocean Surveillance • Ocean Surface Currents • Produce wind-wave numerical
forecast models (from WV mode data)
• Ocean Wave / Spectra
• Ocean Surface Winds
Forest Monitoring • Detect changes in forest growth and • Forest Monitoring for Sustainable
land cover patterns Forest Management
• Provide forest type classification • Forest Monitoring for Environmental
Issues and Nature Protection
• Forest Monitoring for Climatic
Change
Water Management and • ability to delineate between water and • Support Soil protection initiatives
Soil Protection land boundaries due to the sensitivity
• Support geo-information needs of the
of SAR to surface roughness
environmental community
• soil-moisture measurements
• wetland mapping and discrimination

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Activities/
SAR-enabled Capability Objectives/Services
Applications

Forest Fire Flood • Identify areas burned by forest fires, • Assess impact in terms of human,
Management flooded areas (and areas affected by economic and environmental loss.
other hazards)
• Support the organizations and
• Identify change patterns/trends in the institutions mandated for the
areas affected by various natural management of natural hazards,
hazards throughout the prevention,
anticipation, response and post-
response phases
• Monitoring for seasonal mapping of
the areas burnt by forest fires
• Perform flood risk analysis for flood
risk mapping and potential loss
assessment, based on historical data
• Real-time awareness service for flash
flood anticipation.
Food Security and Crop • Backscattered type classification • Monitoring of global food security
Monitoring and related environmental processes
• Monitoring of actual rainfall and
vegetation growth changes (based on • Assist stakeholders and various
long-term Earth observation time- organizations to better implement their
series) policies towards sustainable
development
• Crop/vegetation classification
• Assist agro-meteorological modeling
and forecasts
• monitoring and forecasts, mainly
aiming at delivering detailed
information on actual acreage during
the agricultural season for major crop
types at planting date, during the crop
growth, and at harvest time,
Global Mapping for the • Backscattered type classification • Increase the effectiveness of the
Humanitarian Community humanitarian community through the
• Identification of slow (e.g. famine)
appropriate and reliable application of
onset crisis areas (based on long-term
geographical information.
Earth observation time-series)
• Better deployment of development aid
• Identification of fast (e.g. earthquake)
training and in-field support
onset crisis areas
• Support to forecasting and alert
• Mapping, cartography and other SAR
services
satellite image-derived information

Each application is best served by specific acquisition modes and product types. The
mapping of applications to acquisition modes and product types are provided in
Table 5-4.

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Table 5-4 Mapping of Applications to Modes and Product Types

Acquisition Mode Product

Type

(Interferometry)
(wide coverage)
IW / EW

GRD
SLC
WV
SM
Applications

Monitoring the European Marine

Environment
 
Monitoring the Arctic Environment and
Sea-Ice Zones
  
Monitoring and Assessing Land Surface-
Motion Risks
  
Open Ocean Surveillance
   
Forest Monitoring
   
Water Management and Soil Protection
   
Forest Fire and Flood Management
  
Food Security and Crop Monitoring
  
Global Mapping for the Humanitarian
Community
  

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Date: 25/03/2016

6 LEVEL 2 PRODUCTS OVERVIEW

This section presents an overview of the Sentinel-1 Level 2 products and their
properties. Section 6.1 summarizes the Level 2 product family and the main
properties of each product in the family. Section 6.2 briefly describes each product
type. Section 6.3 describes how the slicing scenario impacts L2 products
characteristics. Finally, Sections 6.4, 6.4.2 and 6.4.3 describe Sentinel-1 Level 2
applications that can make use of Ocean Swell Spectra, Ocean Wind Field and
Radial Surface Velocity information respectively.

6.1 Products Summary

For the Sentinel-1 acquisition modes discussed in Section 3.3, one type of L2
product is defined: OCeaN (OCN). The OCN product may contain the following
components:
a) Ocean SWell spectra (OSW)
b) Ocean WInd field (OWI)
c) Radial Surface VeLocity (RVL)

Table 6-1 presents all the valid combinations of acquisition modes, product type and
component types for the Level 2 products as well as the type of the corresponding
input Level 1 product.

Table 6-1 Level 2 Product Family Summary

Acq. Product Type Component Type Input Level 1 Product Type

Mode

OSW SLC
SM OCN OWI GRD
RVL SLC
OWI GRD
IW OCN
RVL SLC
OWI GRD
EW OCN
RVL SLC
OSW
WV OCN SLC
RVL

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Issue/Revision:
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Date: 25/03/2016

6.2 Product Type Descriptions

6.2.1 Ocean Products (OCN)

Sections 6.2.1.1, 6.2.1.2 and 6.2.1.3 give a brief description of the component types
that compose a Sentinel-1 L2 OCN product.

6.2.1.1 Ocean Swell Spectra Component (OSW)

The OSW component of the OCN product is a two-dimensional ocean surface swell
spectra estimated from a Level 1 SLC image by inversion of the corresponding
image cross-spectra. The cross spectra are computed by performing multi-looking in
azimuth followed by co- and cross-spectra estimation among the detected individual
look images. The OSW swell spectra is computed for each SLC vignette for WV
mode, or for sub-images extracted from an SLC image for SM mode.

The OSW component is given on log-polar grid for the wavenumber and direction.
The spatial and spectral resolutions depend on the mode of the SAR instrument.
Because of the nature of SAR ocean imaging, the actual spectral resolution also
depends on the direction of wave propagation relative to azimuth and the sea state.

The OSW component contains one estimate of the wind speed and direction per
ocean swell spectrum, as well as parameters derived from the ocean swell spectra
(integrated wave parameters for the five most energetic partitions) and from the
vignette (image statistics). The OSW component also contains a quality cross-
spectra per ocean wave spectra.

The spatial coverage of the OSW component is equal to the spatial coverage of the
corresponding L1 WV SLC vignette or L1 SM SLC sub-image, limited to ocean
areas.

The OSW component cannot be generated from TOPSAR data, since individual
looks with sufficient time separation are required. The obtained inter look time
separation within one burst is too short due to the progressive scanning (i.e. short
dwell time). Individual looks from neighbouring bursts require significant spatial
overlap, which is not achieved in full resolution with the standard IW and EW
configurations of the TOPSAR mode.

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Date: 25/03/2016

6.2.1.2 Ocean Wind Field Component (OWI)

The OWI component of the OCN product is a gridded estimate of the surface wind
speed and direction at a height of 10 m above the ocean surface. The spatial
resolution of the SAR wind speed is lower than the resolution of the original L1
product and depends on the level of uncorrelated speckle noise. SAR wind speed
and direction will be provided at the same resolution even if a priori wind direction
from SAR-observed wind streaks or from a Numerical Weather Prediction (NWP)
model has lower resolution. The spatial resolution of the wind estimate is 1 km for
all modes except WV mode for which it is 20 km. In practice, the wind estimate can
have a spatial resolution as fine as 500 m, depending on the effective signal to noise
ratio, compared with a spatial resolution of 25 km for scatterometer wind products.
Such high-resolution products could be of major benefit for coastal monitoring
applications.

It is important to note that SAR wind retrieval geophysical model functions are
designed to retrieve the equivalent neutral stability wind speed at a height of 10 m
above the ocean surface. The model responds to changes in roughness at the ocean
surface, but cannot respond directly to changes in wind speed due to atmospheric
stratification. The equivalent neutral stability wind speed is defined as the mean
wind speed that would be observed if there was neutral atmospheric stratification.

For WV, the wind information comes from the ECMWF atmospheric model and is
reported in the OSW component, while for SM and TOPS it is derived from the L1
data and reported in the OWI component.

6.2.1.3 Radial Surface Velocity Component (RVL)

The RVL component of the OCN product is calculated based on the difference
between the measured L2 Doppler grid and the geometrical Doppler calculated by
the L1 processor. The measured L2 Doppler grid accounts for the antenna
mispointing Doppler by including the antenna error matrix in the antenna model
synthesis. The formula used to calculate the radial velocity, [m/s] from the
corrected Doppler frequency, [Hz] is given as:

The variance of the radial velocity as a function of the variance of the Doppler
frequency is then easily given from the same formula as:

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The L2 Doppler is computed on a grid similar to the OWI component grid and
provides an estimate of the Doppler frequency and the Doppler spectral width. The
uncertainties of the estimates are also provided for both the Doppler and radial
velocity.

The Doppler frequency and the Doppler spectral width are estimated based on fitting
the azimuth spectral profile of the data to the antenna model taking into account
additive noise, aliasing, and side band effects. The Doppler frequency provided in
the product is the pure Doppler frequency estimated from the SLC data without
correcting for geometry and mispointing errors.

The radial velocity can be used, in combination with the estimated wind field, to
retrieve the radial component of the surface current field. However, this is not
provided as part of the L2 processing.

6.3 Slicing Impact on L2 Products

L2 products may be generated from an L1 product covering a segment of data (non-

slicing scenario). In this case, L2 products correspond to the segment and are called
L2 individual scene products.

L2 products may also be generated from an L1 slice product that covers a single
slice (slicing scenario before concatenation of L1 slices was performed). In this
case, L2 products correspond to a single slice and are called L2 slice products. The
L2 slices are not processed in a way that would allow easy concatenation between
them; in other words the grids are not aligned between L2 slices. Note that having
assembled L2 products covering the complete segment is not necessary for L2
applications.

L2 product characteristics described in Sections 6 and 8 are not affected by slicing

in the sense that an L2 individual scene product (non-slicing scenario) and a set of
L2 slice products (slicing scenario without concatenation of L1 slice products)
generated from the same segment of data have the same approximate characteristics
(collectively for the L2 slice products).

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MPC-0239
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Date: 25/03/2016

6.4 Applications for L2 OCN Products

6.4.1 OSW Component

6.4.1.1 Applications

The following applications can benefit from the OSW component of Sentinel-1
OCN products:
a) Numerical Weather Prediction Models and Wave Forecasting: Since
ocean swell systems are observed to propagate over long distances, their
energy should be conserved or weakly dissipated. However, limited
quantitative information is available on this topic leading to relatively poor
prediction of swell systems [R-10]. Numerical wave models that neither
account specifically for swell dissipation, nor assimilate wave measurements,
invariably overestimate significant wave heights in the tropics [R-11], [R-12].
The OSW component can be used to assess the performance of swell
prediction in global numerical wave models, and thus help improve the
models. The OSW component can be used to assess the performance of swell
prediction in global NWP models, and can thus help to improve the models.
Another related application is the assimilation of OSW components into
operational numerical wave prediction models such as Wave Prediction Model
(WAM). Impact studies have been conducted and validation shows a positive
impact in swell dominated areas [R-13].
b) Wave Climate: The OSW component can provide input to a global database
of high-quality wave information. In combination with existing software
packages (e.g., statistical and wave propagation tools) that utilize the wave
database, wave climate statistics and/or time series of wave height, period and
direction can be provided at any coastal or offshore site worldwide. Such tools
exist already in the market [R-14].
c) Earth Observation System: Earth observation systems rely extensively on
satellite remote sensing techniques for ocean surface winds, sea surface
temperature, sea level, ocean colour, and sea ice, which all again are highly
affected by ocean waves. The mutual coupling between different ocean
parameters and how they are manifested in satellite measurements, require
precise modelling and measurements of all key ocean parameters. Since ocean
waves can be viewed as the “gearbox” between atmosphere and ocean, a
detailed understanding and knowledge of waves can significantly improve the
parameterisation of air-sea fluxes and surface processes [R-15].

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Date: 25/03/2016

6.4.1.2 GMES services

The following GMES services are expected to benefit from the OSW component of
Sentinel-1 OCN products:
a) Marine and coastal environmental information services: The objective of
the GMES marine core services is to streamline consistent European
capacities for forecasting, monitoring and reporting on the ocean state, and to
foster derived applications (downstream GMES services) on specific
environmental and safety issues, for both the global ocean and the regional
European seas. Considering the applications above, the GMES services that
benefit from the OSW component indirectly through these applications are
related to:
• Exploitation and management of ocean resources (e.g. offshore oil and
gas industry, fisheries);
• Safety and efficiency of maritime transport, shipping, and naval
operations;
• Marine research (e.g. understanding of the oceans and their ecosystems,
of ocean climate variability);
• Seasonal climate prediction;
• Coastal management and planning (e.g. coastal flooding and erosion).
b) The OSW component is a natural part of the open ocean (sea-state) application
areas of Sentinel-1 in relation to the Marine Core Services [R-16].

6.4.1.3 Basic User Requirements

The two main users of the OSW component are the meteorological community and
the oceanographic service providers. The meteorological community requires
systematic, near-real time access to the products acquired globally over the open
ocean. The preferable Sentinel-1 mode of operation for these users is the Wave
Mode.

The oceanographic service providers require both systematic and on-demand

products from global (open ocean) and local (coastline) coverage. The preferable
Sentinel-1 mode of operation is the Stripmap mode over coastline (on-demand) and
Wave Mode over open ocean areas (systematic).

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Date: 25/03/2016

6.4.2 OWI Component

6.4.2.1 Applications
The following applications can benefit from the OWI component of Sentinel-1 OCN
products:
a) Numerical Weather Prediction Models Forecast: It is well known that wind
is poorly represented at very high resolution in numerical models. The OWI
component can be used to assess the performance of wind prediction in coastal
areas where NWP models have difficulties accounting for complex orographic
effects. Another related application is the assimilation of OWI components
into NWP models.
b) Wind Climate: The OWI component can provide input to a global database of
high-quality wind information. Wind climate statistics and/or time series of
wind speed and direction can be provided at any coastal or offshore site
worldwide.

6.4.2.2 GMES Services

The following GMES services are expected to benefit from the OWI component of
Sentinel-1 OCN products:
a) Marine and coastal environmental information services: The objective of
the GMES marine core services is to streamline consistent European
capacities for forecasting, monitoring and reporting on the ocean state, and to
foster derived applications (downstream GMES services) on specific
environmental and safety issues, for both the global ocean and the regional
European seas. Considering the applications above, the GMES services that
benefit from the OWI component indirectly through these applications are
related to:
• Oil spill detection from SAR images since the SAR-derived wind is a
key parameter to help discriminate look-alikes from actual spills. This is
currently used in CLEANSEANET operational oil spill service provided
by EMSA; the wind retrieval is an external product used for oil spill
monitoring since the synoptic view on the wind map helps to actually
search for the oil spills. In existing operational environment such as with
EMSA, the L2 product is generated just before starting the oil analysis
since the L2 are not produced in the same software that L1 processing.
• Exploitation and management of ocean resources (e.g. offshore oil and
gas industry, fisheries);
• Safety and efficiency of maritime transport, shipping, and naval
operations;
• Marine research (e.g. understanding of the oceans and their ecosystems,
of ocean climate variability);

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• Seasonal climate prediction;

• Coastal management and planning (e.g. coastal flooding and erosion).
b) The OWI component is a natural part of the open ocean (sea-state)
surveillance defined as one of the application areas of Sentinal-1 in relation to
the Marine Core Services [R-16].

Note that Met centers or GMES services are only interested in L2 products, whereas
experts are interested in L1 products to work on algorithms or provide L2 to end
users. But we know from experience that operational processing in ground segments
should be driven by experts to provide fast response to the many issues that can arise
at any time of the mission on the L1 products that will not necessarily be easily
detected on L1 but clearly modify the quality of L2. This is particularly the case
with the incidence angle annotation and absolute calibration.

6.4.3 RVL Component

The applications for the RVL component of Sentinel-1 OCN products are similar to
those for the OWI component (refer to Section 6.4.2.1).

The GMES services expected to benefit from the RVL component are similar to
those for the OWI component (refer to Section 6.4.2.2).

The RVL component can be used in combination with the OWI component to
extract the radial surface current field.

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Issue/Revision:
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Date: 25/03/2016

7 LEVEL 1 PRODUCTS DEFINITION

This section provides the detailed characteristics of the standard Sentinel-1 Level 1
products for each image mode. Descriptions of the terms used in the product
definition tables are given in Appendix A1.

The Level 1 products are identified by a combination of up to three mnemonics,

each corresponding to the following acquisition mode or product characteristics:
• The acquisition mode, as defined in Section 3.3 (SM, IW, EW or WV).
• The product type, as defined in Section 5.2 (SLC or GRD).
• The resolution class, as defined in Section 5.1 (FR, HR or MR).

If one of the mnemonics is not applicable, for instance the resolution class for SLC
products, it will be omitted. For example, the identifier IW_GRD_HR corresponds
to a high resolution multi-look GRD product generated from data acquired in IW
mode.

The image quality values currently included in the tables (resolution, ISLR, PSLR
ambiguity ratios, NESZ, radiometric accuracy, location accuracy) are to be
understood in the theoretical sense. The pixel localisation accuracy values are
currently the predicted values, which are based on the calibration and performance
budgets presented in [R-4].

The actual image quality characteristics will be derived from measurement

performed on real data images, during the commissioning phase.

The number of lines and the data volumes in the tables are provided as examples
only. Actual products have a variable number of lines and a variable volume.

The resolutions in the tables correspond to an average over the minimum and
maximum orbits, and to the following swath range positions:
• near range, for azimuth resolution
• mid range, for ground range resolution
• any, for slant range resolution (it does not vary with the range position within
a swath).

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Date: 25/03/2016

7.1 Stripmap L1 Products Definition

7.1.1 Stripmap SLC Product Definition

Table 7-1 Stripmap SLC Product

Product ID SM_SLC
Product Type Stripmap, Slant-Range, Single Look, Complex
Main Product Characteristics
Pixel Value Complex
Coordinate System Slant Range
Bits Per Pixel 16 I and 16 Q
Polarisation Options Single (HH or VV) or Dual (HH+HV or VV+VH)
Beam ID S1 S2 S3 S4 S5 S6
Ground Range Coverage [km] 80.1
Slant Range Resolution [m] 1.7 2 2.5 3 3.3 3.6
Azimuth Resolution [m] 4.3 4.9 3.6 4.8 3.9 4.9
Slant Range Pixel Spacing [m] 1.5 1.8 2.2 2.6 2.9 3.1
Azimuth Pixel Spacing [m] 3.6 4.2 3.5 4.1 3.6 4.1
Incidence angle [°] 22.3 25.6 31.2 36.4 41 43.8
Equivalent Number of Looks (ENL) 1
Radiometric Resolution 3
Product Performance Parameters
Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -21.2
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -16.1
Distributed Target Ambiguity Ratios [dB] < -22.3
Point Target Ambiguity Ratios [dB] < -32.2
NESZ [dB] < -22.2
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) 2.5
SAR Processing Parameters
Number of Looks (range x azimuth) 1x1
Look overlap (range x azimuth) N/A
Range Look Bandwidth [Hz] 87.6 74.2 59.4 50.6 44.9 42.2
Azimuth Look Bandwidth [Hz] 1586 1405 1904 1429 1886 1398
Range Hamming Weighting Coefficient 0.75 0.75 0.75 0.75 0.75 0.75
Azimuth Hamming Weighting Coefficient 0.75 0.75 0.75 0.75 0.65 0.75

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Data Size & Volume for a 25 Second Long (Approximately 170 km Azimuth Coverage) Product
Approx # of Lines 46800 40400 48200 41300 47500 41600
Approx # of Pixels per Line 21500 20600 19600 19000 18600 18400
Max Data Volume (Single Polarisation) [MB] 3840 3176 3605 2995 3372 2921
Max Data Volume (Dual Polarisation) [MB] 7680 6352 7210 5990 6744 5842
Quick-Look Characteristics
Bits Per Pixel 8
Range Decimation Factor 39
Azimuth Decimation Factor 24
Range Averaging Factor 59
Azimuth Averaging Factor 36
Range Resolution [m] 66.8 78.8 98.5 115.6 130.3 138.6
Azimuth Resolution [m] 103.2 116.4 85.9 114.3 94.8 116.7
Range Pixel Spacing [m] 58 68.5 85.6 100.5 113.2 120.5
Azimuth Pixel Spacing [m] 87.4 101.4 84.9 98.9 85.9 98
Approx # of Lines 1950 1690 2010 1730 1980 1740
Approx # of Pixels per Line 560 530 510 490 480 480

7.1.2 Stripmap GRD Products Definition

Table 7-2 Stripmap GRD FR Product

Product ID SM_GRD_FR
Product Type Stripmap, Ground Range, Multi-look, Detected, Full Resolution
Main Product Characteristics
Pixel Value Magnitude Detected
Coordinate System Ground Range
Bits Per Pixel 16
Polarisation Options Single (HH or VV) or Dual (HH+HV or VV+VH)
Beam ID S1 S2 S3 S4 S5 S6
Ground Range Coverage [km] 80.1
Ground Range Resolution [m] 8.1 8.4 8.8 9 9.2 9.2
Azimuth Resolution [m] 8.1 8.7 8.8 8.9 8.9 9.1
Ground Range Pixel Spacing [m] 4
Azimuth Pixel Spacing [m] 4
Incidence angle [°] 22.3 25.6 31.2 36.4 41 43.8
Equivalent Number of Looks (ENL) 3.5 3.5 3.7 3.5 3.7 3.5
Radiometric Resolution 1.9 1.9 1.8 1.9 1.8 1.9

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Product Performance Parameters

Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -21.2
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -16.1
Distributed Target Ambiguity Ratios [dB] < -22.3
Point Target Ambiguity Ratios [dB] < -32.2
NESZ [dB] < -22.2
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) 2.5
SAR Processing Parameters
Number of Looks (range x azimuth) 2x2
Look overlap (range x azimuth) 0.200 x 0.200
Range Look Bandwidth [Hz] 48.7 41.2 33 28.1 24.9 23.4
Azimuth Look Bandwidth [Hz] 881 781 1058 794 1048 777
Range Hamming Weighting Coefficient 0.75 0.75 0.75 0.75 0.75 0.75
Azimuth Hamming Weighting Coefficient 0.7 0.75 0.52 0.7 0.52 0.7
Data Size & Volume for a 25 Second Long (Approximately 170 km Azimuth Coverage) Product
Approx # of Lines 48700
Approx # of Pixels per Line 22900
Max Data Volume (Single Polarisation) [MB] 2128
Max Data Volume (Dual Polarisation) [MB] 4256
Quick-Look Characteristics
Bits Per Pixel 8
Range Decimation Factor 40
Azimuth Decimation Factor 40
Range Averaging Factor 60
Azimuth Averaging Factor 60
Range Resolution [m] 325 336.5 350.6 359.9 366.5 369.9
Azimuth Resolution [m] 322.3 349.3 351.8 357.2 354.6 364.6
Range Pixel Spacing [m] 140
Azimuth Pixel Spacing [m] 140
Approx # of Lines 1220
Approx # of Pixels per Line 580

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Table 7-3 Stripmap GRD HR Product

Product ID SM_GRD_HR
Product Type Stripmap, Ground Range, Multi-look, Detected, High Resolution
Main Product Characteristics
Pixel Value Magnitude Detected
Coordinate System Ground Range
Bits Per Pixel 16
Polarisation Options Single (HH or VV) or Dual (HH+HV or VV+VH)
Beam ID S1 S2 S3 S4 S5 S6
Ground Range Coverage [km] 80.1
Ground Range Resolution [m] 21.4 22.2 23.1 23.7 24.2 24.4
Azimuth Resolution [m] 21.3 23 23.2 23.6 23.4 24.1
Ground Range Pixel Spacing [m] 10
Azimuth Pixel Spacing [m] 10
Incidence angle [°] 22.3 25.6 31.2 36.4 41 43.8
Equivalent Number of Looks (ENL) 26.8 26.3 29.7 26.8 29.7 26.8
Radiometric Resolution 0.8 0.8 0.7 0.8 0.7 0.8
Product Performance Parameters
Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -21.2
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -16.1
Distributed Target Ambiguity Ratios [dB] < -22.3
Point Target Ambiguity Ratios [dB] < -32.2
NESZ [dB] < -22.2
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) 2.5
SAR Processing Parameters
Number of Looks (range x azimuth) 6x6
Look overlap (range x azimuth) 0.250 x 0.250
Range Look Bandwidth [Hz] 18.4 15.6 12.5 10.7 9.5 8.9
Azimuth Look Bandwidth [Hz] 334 296 401 301 397 294
Range Hamming Weighting Coefficient 0.75 0.75 0.75 0.75 0.75 0.75
Azimuth Hamming Weighting Coefficient 0.7 0.75 0.52 0.7 0.52 0.7
Data Size & Volume for a 25 Second Long (Approximately 170 km Azimuth Coverage) Product
Approx # of Lines 17100
Approx # of Pixels per Line 8100
Max Data Volume (Single Polarisation) [MB] 265
Max Data Volume (Dual Polarisation) [MB] 530

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Quick-Look Characteristics
Bits Per Pixel 8
Range Decimation Factor 16
Azimuth Decimation Factor 16
Range Averaging Factor 24
Azimuth Averaging Factor 24
Range Resolution [m] 343 355.2 370 379.9 386.8 390.4
Azimuth Resolution [m] 340.3 368.7 371.3 377 374.3 384.8
Range Pixel Spacing [m] 160
Azimuth Pixel Spacing [m] 160
Approx # of Lines 1070
Approx # of Pixels per Line 510

Table 7-4 Stripmap GRD MR Product

Product ID SM_GRD_MR
Product Type Stripmap, Ground Range, Multi-look, Detected, Medium Resolution
Main Product Characteristics
Pixel Value Magnitude Detected
Coordinate System Ground Range
Bits Per Pixel 16
Polarisation Options Single (HH or VV) or Dual (HH+HV or VV+VH)
Beam ID S1 S2 S3 S4 S5 S6
Ground Range Coverage [km] 80.1
Ground Range Resolution [m] 78 80.7 84.1 86.4 87.9 88.7
Azimuth Resolution [m] 77.3 83.8 84.4 85.7 85.1 87.5
Ground Range Pixel Spacing [m] 40
Azimuth Pixel Spacing [m] 40
Incidence angle [°] 22.3 25.6 31.2 36.4 41 43.8
Equivalent Number of Looks (ENL) 358.3 350.5 398.4 358.3 398.4 358.3
Radiometric Resolution 0.2 0.2 0.2 0.2 0.2 0.2

ESA Unclassified – For Official Use

7-6
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Product Performance Parameters

Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -21.2
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -16.1
Distributed Target Ambiguity Ratios [dB] < -22.3
Point Target Ambiguity Ratios [dB] < -32.2
NESZ [dB] < -22.2
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) 2.5
SAR Processing Parameters
Number of Looks (range x azimuth) 22 x 22
Look overlap (range x azimuth) 0.225 x 0.225
Range Look Bandwidth [Hz] 5.1 4.3 3.4 2.9 2.6 2.4
Azimuth Look Bandwidth [Hz] 92 81 110 83 109 81
Range Hamming Weighting Coefficient 0.75 0.75 0.75 0.75 0.75 0.75
Azimuth Hamming Weighting Coefficient 0.7 0.75 0.52 0.7 0.52 0.7
Data Size & Volume for a 25 Second Long (Approximately 170 km Azimuth Coverage) Product
Approx # of Lines 4300
Approx # of Pixels per Line 2100
Max Data Volume (Single Polarisation) [MB] 18
Max Data Volume (Dual Polarisation) [MB] 36
Quick-Look Characteristics
Bits Per Pixel 8
Range Decimation Factor 4
Azimuth Decimation Factor 4
Range Averaging Factor 6
Azimuth Averaging Factor 6
Range Resolution [m] 311.9 323 336.4 345.5 351.7 355
Azimuth Resolution [m] 309.4 335.3 337.6 342.8 340.3 349.9
Range Pixel Spacing [m] 160
Azimuth Pixel Spacing [m] 160
Approx # of Lines 1080
Approx # of Pixels per Line 530

ESA Unclassified – For Official Use

7-7
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

7.2 Interferometric Wide Swath L1 Products Definition

7.2.1 Interferometric Wide Swath SLC Product Definition

Table 7-5 Interferometric Wide Swath SLC Product

Product ID IW_SLC
Product Type Interferometric Wide Swath, Slant-Range, Single Look, Complex
Main Product Characteristics
Pixel Value Complex
Coordinate System Slant Range
Bits Per Pixel 16 I and 16 Q
Polarisation Options Single (HH or VV) or Dual (HH+HV or VV+VH)
Beam ID IW1 IW2 IW3
Ground Range Coverage [km] 251.8
Slant Range Resolution [m] 2.7 3.1 3.5
Azimuth Resolution [m] 22.5 22.7 22.6
Slant Range Pixel Spacing [m] 2.3 2.3 2.3
Azimuth Pixel Spacing [m] 14.1 14.1 14.1
Incidence angle [°] 32.9 38.3 43.1
Equivalent Number of Looks (ENL) 1
Radiometric Resolution 3
Product Performance Parameters
Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -21.2
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -16.1
Distributed Target Ambiguity Ratios [dB] < -22.5
Point Target Ambiguity Ratios [dB] < -27.2
NESZ [dB] < -23.7
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) 7

ESA Unclassified – For Official Use

7-8
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

SAR Processing Parameters

Number of Looks (range x azimuth) 1x1
Look overlap (range x azimuth) N/A
Range Look Bandwidth [Hz] 56.5 48.3 42.8
Azimuth Look Bandwidth [Hz] 315 301 301
Range Hamming Weighting Coefficient 0.75 0.75 0.75
Azimuth Hamming Weighting Coefficient 0.7 0.75 0.75
Data Size & Volume for a 25 Second Long (Approximately 170 km Azimuth Coverage) Product
Approx # of Lines 14600 14600 14600
Approx # of Pixels per Line 20800 24800 24100
Max Data Volume (Single Polarisation) [MB] 1160 1383 1344
Max Data Volume (Dual Polarisation) [MB] 2320 2766 2688
Quick-Look Characteristics
Bits Per Pixel 8
Range Decimation Factor 46
Azimuth Decimation Factor 6
Range Averaging Factor 69
Azimuth Averaging Factor 9
Range Resolution [m] 122.1 142.8 161.2
Azimuth Resolution [m] 136.96 137.02 136.91
Range Pixel Spacing [m] 106.1 106.1 106.1
Azimuth Pixel Spacing [m] 84.5 84.5 84.5
Approx # of Lines 2440 2440 2440
Approx # of Pixels per Line 460 540 530

ESA Unclassified – For Official Use

7-9
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

7.2.2 Interferometric Wide Swath GRD Products Definition

Table 7-6 Interferometric Wide Swath GRD HR Product

Product ID IW_GRD_HR
Product Type Interferometric Wide Swath, Ground-Range, Multi-Look, Detected, High Resolution
Main Product Characteristics
Pixel Value Magnitude Detected
Coordinate System Ground Range
Bits Per Pixel 16
Polarisation Options Single (HH or VV) or Dual(HH+HV or VV+VH)
Beam ID IW1 IW2 IW3
Ground Range Coverage [km] 251.8
Ground Range Resolution [m] 20.4 20.3 20.5
Azimuth Resolution [m] 22.5 22.6 22.6
Ground Range Pixel Spacing [m] 10
Azimuth Pixel Spacing [m] 10
Incidence angle [°] 32.9 38.3 43.1
Equivalent Number of Looks (ENL) 4.4 4.4 4.3
Radiometric Resolution 1.7 1.7 1.7
Product Performance Parameters
Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -21.2
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -16.1
Distributed Target Ambiguity Ratios [dB] < -22.5
Point Target Ambiguity Ratios [dB] < -27.2
NESZ [dB] < -23.7
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) 7
SAR Processing Parameters
Number of Looks (range x azimuth) 5x1
Look overlap (range x azimuth) 0.250 x 0.000
Range Look Bandwidth [Hz] 14.1 12.1 10.7
Azimuth Look Bandwidth [Hz] 315 301 301
Range Hamming Weighting Coefficient 0.7 0.73 0.75
Azimuth Hamming Weighting Coefficient 0.7 0.75 0.75

ESA Unclassified – For Official Use

7-10
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Data Size & Volume for a 25 Second Long (Approximately 170 km Azimuth Coverage) Product
Approx # of Lines 17100
Approx # of Pixels per Line 25200
Max Data Volume (Single Polarisation) [MB] 822
Max Data Volume (Dual Polarisation) [MB] 1644
Quick-Look Characteristics
Bits Per Pixel 8
Range Decimation Factor 50
Azimuth Decimation Factor 49
Range Averaging Factor 75
Azimuth Averaging Factor 74
Range Resolution [m] 1017.6 1016.3 1026.5
Azimuth Resolution [m] 1104.6 1109.6 1106.31060
Range Pixel Spacing [m] 500
Azimuth Pixel Spacing [m] 490
Approx # of Lines 350
Approx # of Pixels per Line 510

Table 7-7 Interferometric Wide Swath GRD MR Products

Product ID IW_GRD_MR
Product Type Interferometric Wide Swath, Ground-Range, Multi-Look, Detected, Medium
Resolution
Main Product Characteristics
Pixel Value Magnitude Detected
Coordinate System Ground Range
Bits Per Pixel 16
Polarisation Options Single (HH or VV) or
Dual(HH+HV or VV+VH)
Beam ID IW1 IW2 IW3
Ground Range Coverage [km] 251.8
Ground Range Resolution [m] 87.9 87.8 88.7
Azimuth Resolution [m] 90.2 90.6 90.3
Ground Range Pixel Spacing [m] 40
Azimuth Pixel Spacing [m] 40
Incidence angle [°] 32.9 38.3 43.1
Equivalent Number of Looks (ENL) 83.9 81.2 80.5
Radiometric Resolution 0.4 0.5 0.5

ESA Unclassified – For Official Use

7-11
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Product Performance Parameters

Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -21.2
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -16.1
Distributed Target Ambiguity Ratios [dB] < -22.5
Point Target Ambiguity Ratios [dB] < -27.2
NESZ [dB] < -23.7
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 1
sigma)
Relative Radiometric Accuracy [dB] (3 0.1
sigma)
Absolute Location Accuracy [m] (NRT) 7
SAR Processing Parameters
Number of Looks (range x azimuth) 22 x 5
Look overlap (range x azimuth) 0.225 x 0.250
Range Look Bandwidth [Hz] 3.3 2.8 2.5
Azimuth Look Bandwidth [Hz] 79 75 75
Range Hamming Weighting Coefficient 0.7 0.73 0.75
Azimuth Hamming Weighting Coefficient 0.7 0.75 0.75
Data Size & Volume for a 25 Second Long (Approximately 170 km Azimuth Coverage) Product
Approx # of Lines 4300
Approx # of Pixels per Line 6300
Max Data Volume (Single Polarisation) [MB] 52
Max Data Volume (Dual Polarisation) [MB] 104
Quick-Look Characteristics
Bits Per Pixel 8
Range Decimation Factor 12
Azimuth Decimation Factor 12
Range Averaging Factor 18
Azimuth Averaging Factor 18
Range Resolution [m] 1054.7 1053.4 1064
Azimuth Resolution [m] 1082 1087 1083.7
Range Pixel Spacing [m] 480
Azimuth Pixel Spacing [m] 480
Approx # of Lines 360
Approx # of Pixels per Line 530

ESA Unclassified – For Official Use

7-12
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

7.3 Extra Wide Swath L1 Products Definition

7.3.1 Extra Wide Swath SLC Product Definition

Table 7-8 Extra Wide Swath SLC Product

Product ID EW_SLC
Product Type Extra Wide Swath, Slant-Range, Single Look, Complex
Main Product Characteristics
Pixel Value Complex
Coordinate System Slant Range
Bits Per Pixel 16 I and 16 Q
Polarisation Options Single (HH or VV) or Dual (HH+HV or VV+VH)
Beam ID EW1 EW2 EW3 EW4 EW5
Ground Range Coverage [km] 410
Slant Range Resolution [m] 7.9 9.9 11.6 13.3 14.4
Azimuth Resolution [m] 43.7 44.3 45.2 45.6 44.0
Slant Range Pixel Spacing [m] 5.9 5.9 5.9 5.9 5.9
Azimuth Pixel Spacing [m] 19.9 19.9 19.9 19.9 19.9
Incidence angle [°] 23.7 30.9 36.2 40.9 44.5
Equivalent Number of Looks (ENL) 1
Radiometric Resolution 3
Product Performance Parameters
Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -21.2
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -16.1
Distributed Target Ambiguity Ratios [dB] < -23.1
Point Target Ambiguity Ratios [dB] < -27.4
NESZ [dB] < -23.1
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) Not Specified
SAR Processing Parameters
Number of Looks (range x azimuth) 1x1
Look overlap (range x azimuth) N/A
Range Look Bandwidth [Hz] 22.2 15.1 12.9 11.3 10.4
Azimuth Look Bandwidth [Hz] 225 154 151 149 154
Range Hamming Weighting Coefficient 0.6 0.75 0.75 0.75 0.75
Azimuth Hamming Weighting Coefficient 0.5 0.75 0.75 0.75 0.75

ESA Unclassified – For Official Use

7-13
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Data Size & Volume for a 60 Second Long (Approximately 400 km Azimuth Coverage) Product
Approx # of Lines 23700 23700 23700 23700 23600
Approx # of Pixels per Line 8600 7000 8700 8700 7500
Max Data Volume (Single Polarisation) [MB] 781 636 790 790 678
Max Data Volume (Dual Polarisation) [MB] 1562 1272 1580 1580 1356
Quick-Look Characteristics
Bits Per Pixel 8
Range Decimation Factor 16
Azimuth Decimation Factor 4
Range Averaging Factor 24
Azimuth Averaging Factor 6
Range Resolution [m] 126.4 158.9 186 212.4 230.7
Azimuth Resolution [m] 174.8 177.2 180.7 182.2 176.2
Range Pixel Spacing [m] 93.9 93.9 93.9 93.9 93.9
Azimuth Pixel Spacing [m] 79.6 79.6 79.6 79.6 79.6
Approx # of Lines 5930 5930 5930 5930 5900
Approx # of Pixels per Line 540 440 550 550 470

7.3.2 Extra Wide Swath GRD Products Definition

Table 7-9 Extra Wide Swath GRD HR Product

Product ID EW_GRD_HR
Product Type Extra Wide Swath, Ground-Range, Multi-Look, Detected, High Resolution
Main Product Characteristics
Pixel Value Magnitude Detected
Coordinate System Ground Range
Bits Per Pixel 16
Polarisation Options Single (HH or VV) or Dual (HH+HV or VV+VH)
Beam ID EW1 EW2 EW3 EW4 EW5
Ground Range Coverage [km] 410
Ground Range Resolution [m] 49.1 50.3 50.4 50.7 51.4
Azimuth Resolution [m] 51.5 51.1 51.34 51.1 51.5
Ground Range Pixel Spacing [m] 25
Azimuth Pixel Spacing [m] 25
Incidence angle [°] 23.7 30.9 36.2 40.9 44.5
Equivalent Number of Looks (ENL) 2.8 2.7 2.7 2.7 2.7
Radiometric Resolution 2 2.1 2.1 2.1 2.1

ESA Unclassified – For Official Use

7-14
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Product Performance Parameters

Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -28.3
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -19.4
Distributed Target Ambiguity Ratios [dB] < -23.1
Point Target Ambiguity Ratios [dB] < -27.4
NESZ [dB] < -23.1
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) Not Specified
SAR Processing Parameters
Number of Looks (range x azimuth) 3x1 3x1 3x1 3x1 3x1
Look overlap (range x azimuth) 0.250 x 0.000
Range Look Bandwidth [Hz] 8.9 6 5.2 4.5 4.2
Azimuth Look Bandwidth [Hz] 155 154 151 149 154
Range Hamming Weighting Coefficient 0.6 0.7 0.72 0.75 0.75
Azimuth Hamming Weighting Coefficient 0.6 0.61 0.62 0.63 0.6
Data Size & Volume for a 60 Second Long (Approximately 400 km Azimuth Coverage) Product
Approx # of Lines 16400
Approx # of Pixels per Line 16600
Max Data Volume (Single Polarisation) [MB] 520
Max Data Volume (Dual Polarisation) [MB] 1040
Quick-Look Characteristics
Bits Per Pixel 8
Range Decimation Factor 32
Azimuth Decimation Factor 33
Range Averaging Factor 48
Azimuth Averaging Factor 50
Range Resolution [m] 1571.4 1610.1 1613.8 1623 1645.3
Azimuth Resolution [m] 1699.1 1684.8 1694.2 1686.8 1699.6
Range Pixel Spacing [m] 800
Azimuth Pixel Spacing [m] 825
Approx # of Lines 500
Approx # of Pixels per Line 520

ESA Unclassified – For Official Use

7-15
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Table 7-10 Extra Wide Swath GRD MR Product

Product ID EW_GRD_MR
Product Type Extra Wide Swath, Ground-Range, Multi-Look, Detected, Medium Resolution
Main Product Characteristics
Pixel Value Magnitude Detected
Coordinate System Ground Range
Bits Per Pixel 16
Polarisation Options Single (HH or VV) or Dual (HH+HV or VV+VH)
Beam ID EW1 EW2 EW3 EW4 EW5
Ground Range Coverage [km] 410
Ground Range Resolution [m] 90.8 93.1 93.3 93.8 95.1
Azimuth Resolution [m] 90.1 89.4 89.85 89.45 90.13
Ground Range Pixel Spacing [m] 40
Azimuth Pixel Spacing [m] 40
Incidence angle [°] 23.7 30.9 36.2 40.9 44.5
Equivalent Number of Looks (ENL) 15.2 9.7 9.6 9.5 9.6
Radiometric Resolution 1.0 1.2 1.2 1.2 1.2
Product Performance Parameters
Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -28.3
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -19.4
Distributed Target Ambiguity Ratios [dB] < -23.1
Point Target Ambiguity Ratios [dB] < -27.4
NESZ [dB] < -23.1
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) Not Specified
SAR Processing Parameters
Number of Looks (range x azimuth) 6x3 6x2 6x2 6x2 6x2
Look overlap (range x azimuth) 0.275 x 0.250
Range Look Bandwidth [Hz] 4.8 3.3 2.8 2.4 2.2
Azimuth Look Bandwidth [Hz] 88 88 86 85 88
Range Hamming Weighting Coefficient 0.6 0.7 0.72 0.75 0.75
Azimuth Hamming Weighting Coefficient 0.6 0.61 0.62 0.63 0.6
Data Size & Volume for a 60 Second Long (Approximately 400 km Azimuth Coverage) Product
Approx # of Lines 10300
Approx # of Pixels per Line 10400
Max Data Volume (Single Polarisation) [MB] 205
Max Data Volume (Dual Polarisation) [MB] 410

ESA Unclassified – For Official Use

7-16
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Quick-Look Characteristics
Bits Per Pixel 8
Range Decimation Factor 20
Azimuth Decimation Factor 21
Range Averaging Factor 30
Azimuth Averaging Factor 32
Range Resolution [m] 1816.9 1861.7 1865.9 1876.6 1902.3
Azimuth Resolution [m] 1892.2 1876.26 1886.8 1878.5 1892.7
Range Pixel Spacing [m] 800
Azimuth Pixel Spacing [m] 840
Approx # of Lines 500
Approx # of Pixels per Line 520

ESA Unclassified – For Official Use

7-17
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

7.4 Wave L1 Products Definition

7.4.1 Wave SLC Product Definition

Table 7-11 Wave SLC Product

Product ID WV_SLC
Product Type Wave, Slant-Range, Single Look, Complex
Main Product Characteristics
Pixel Value Complex
Coordinate System Slant Range
Bits Per Pixel 16 I and 16 Q
Polarisation Options Single (HH or VV)
Beam ID WV1 WV2
Ground Range Coverage [km] 20
Slant Range Resolution [m] 2 3.1
Azimuth Resolution [m] 4.8 4.8
Slant Range Pixel Spacing [m] 1.7 2.7
Azimuth Pixel Spacing [m] 4.1 4.1
Incidence angle [°] 23.4 36.4
Equivalent Number of Looks (ENL) 1
Radiometric Resolution 3
Product Performance Parameters
Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -21.2
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -16.1
Distributed Target Ambiguity Ratios [dB] < -27.2
Point Target Ambiguity Ratios [dB] < -34.2
NESZ [dB] < -26.3
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) Not Specified

ESA Unclassified – For Official Use

7-18
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

SAR Processing Parameters

Number of Looks (range x azimuth) 1x1
Look overlap (range x azimuth) N/A
Range Look Bandwidth [Hz] 74.5 48.2
Azimuth Look Bandwidth [Hz] 1428 1429
Range Hamming Weighting Coefficient 0.75 0.75
Azimuth Hamming Weighting Coefficient 0.75 0.75
Data Size & Volume per Vignette
Approx # of Lines 4900 4900
Approx # of Pixels per Line 5000 4700
Max Data Volume (Single Polarisation) [MB] 94 89

7.4.2 Wave GRD Product Definition

Table 7-12 Wave GRD MR Product

Product ID WV_GRD_MR
Product Type Wave, Ground-Range, Multi-Look, Detected Medium Resolution
Main Product Characteristics
Pixel Value Magnitude Detected
Coordinate System Ground Range
Bits Per Pixel 16
Polarisation Options Single (HH or VV)
Beam ID WV1 WV2
Ground Range Coverage [km] 20
Range Resolution [m] 50.8 52.4
Azimuth Resolution [m] 50.6 50.5
Ground Range Pixel Spacing [m] 25
Azimuth Pixel Spacing [m] 25
Incidence angle [°] 23.4 36.4
Equivalent Number of Looks (ENL) 123.7 123.7
Radiometric Resolution 0.4 0.4

ESA Unclassified – For Official Use

7-19
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Product Performance Parameters

Range PSLR [dB] < -21.2
Azimuth PSLR [dB] < -21.2
Range ISLR [dB] < -16.1
Azimuth ISLR [dB] < -16.1
Distributed Target Ambiguity Ratios [dB] < -27.2
Point Target Ambiguity Ratios [dB] < -34.2
NESZ [dB] < -26.3
Channel Co-registration Accuracy [pixels] < 0.25
Absolute Radiometric Accuracy [dB] (3 sigma) 1
Relative Radiometric Accuracy [dB] (3 sigma) 0.1
Absolute Location Accuracy [m] (NRT) Not Specified
SAR Processing Parameters
Number of Looks (range x azimuth) 13 x 13
Look overlap (range x azimuth) 0.250 x 0.200
Range Look Bandwidth [Hz] 7.4 4.8
Azimuth Look Bandwidth [Hz] 135 135
Range Hamming Weighting Coefficient 0.75 0.75
Azimuth Hamming Weighting Coefficient 0.75 0.75
Data Size & Volume per Vignette
Approx # of Lines 800
Approx # of Pixels per Line 800
Max Data Volume per Channel [MB] 2

ESA Unclassified – For Official Use

7-20
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

8 LEVEL 2 PRODUCTS DEFINITION

This section provides the detailed characteristics of the Sentinel-1 L2 products for
each image mode. Descriptions of the terms used in the product definition tables are
given in Appendix A2.

The Level 2 products are identified by a combination of up to two mnemonics, each

corresponding to the following acquisition mode or product type:
• The acquisition mode, as defined in Section 3.3 (SM, IW, EW or WV).
• The product type, as defined in Section 6.1 (OCN).

For example, the identifier SM_OCN corresponds to an OCN product generated

from data acquired in SM mode.

The grid dimensions and data volumes in the tables are provided as examples only.
Actual products have variable grid dimensions and a variable volume.

ESA Unclassified – For Official Use

8-1
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

8.1 Stripmap L2 Products Definition

8.1.1 Stripmap OCN Product Definition

Table 8-1 Stripmap OCN Product

Product ID SM_OCN

Product Type Stripmap Ocean

Main Product Characteristics

Coordinate System Ground Range (OSW, OWI and RVL)

Polarisation Options Single or Dual Co-polarisation (HH or VV)

Beam ID S1 S2 S3 S4 S5 S6

Incidence angle [°] 22.3 25.6 31.2 36.4 41.0 43.8

Main Product Characteristics – OSW specific
4
Ocean Swell Spectra [m ]

2
Quality cross-spectra [m ]

(1)
Ocean Swell Spectra Spatial Resolution [km x km] 20x20

Ocean Swell Spectra Spectral Resolution [m] On average, between 30 and 220 m depending on wave direction
relative to azimuth direction

Ocean Swell Spectra Grid Dimension [azimuth cell x ground 8x5 or 8x4
range cell]
Main Product Characteristics – OWI specific
(2)
Ocean Wind Field Spatial Resolution [km x km] 1x1

Ocean Wind Field Grid Dimension [azimuth cell x ground range 170x80
cell]
Main Product Characteristics – RVL specific
(2)
Radial Surface Velocity Spatial Resolution [km x km] 1.5x1.7

Radial Surface Velocity Grid Dimension [azimuth cell x ground 117 x 47

range cell]
Product Performance Parameters

Product Performance Parameters – OSW specific

Number of Wave Partitions 5

SAR Significant Waveheight [m] >0, RMSe < 0.5, Bias < 0.1

Dominant Wave Length [m]

Dominant Wave Direction [degN]

Azimuth Cut-off Wavelength [m]

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Product ID SM_OCN

Confidence Flag For Wave Direction Retrieval 0 or 1

Product Performance Parameters – OWI specific

Wind Speed [m/s]

Wind Direction [degN]

Product Performance Parameters – RVL specific

Radial Surface Velocity [m/s]

Doppler frequency [Hz]

Processing Parameters

Processing Parameters – OSW specific

Number of individual looks (range x azimuth) 1x3

Frequency separation of neighbouring looks [Hz]

Range Look Bandwidth [Hz]

Azimuth Look Bandwidth [Hz] 0.75 f PRF

Number of Pixels Used in Spectral Estimation [range, azimuth] 256, 256
Low Pass Filter Width for Detrending of Image [m] 1000
Processing Parameters – OWI specific

Geophysical scattering model function CMOD-IFR2 NN or CMOD2-I3 NN

Polarization ratio model Mouche et al (1)
Data Size & Volume for a 25s Long (approximately 170 km Azimuth Coverage) Product
Data Size & Volume

Number of Lines in Spectra 60

Number of Pixels per Line 72
Data Volume per Spectra [bytes] 17280
Total Data Volume of Ocean Swell Spectra Component [bytes] 1816000
Total Data Volume of Ocean Wind Field Component [bytes] 1197000
Total Data Volume of Radial Surface Velocity Component [bytes] 1007000
Total Data Volume of OCN Product [bytes] 4020000

Notes

(1) Product splits 170km x 80km SM image into 8x4 images of

20km x 20km for OSW estimation.

(2) Product splits 170km x 80km SM image into 235x95 images of

0.75km x 0.85km for RVL estimation. Note that the spatial
resolution is approximately twice the grid spacing in RVL

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8.2 Interferometric Wide Swath L2 Products Definition

8.2.1 Interferometric Wide Swath OCN Product Definition

Table 8-2 Interferometric Wide Swath OCN Product

Product ID IW_OCN
Product Type Interferometric Wide Swath Ocean
Main Product Characteristics
Coordinate System Ground Range (OWI and RVL)
Polarisation Options Single or Dual Co-polarisation (HH or VV)
Beam ID IW1 IW2 IW3
Incidence angle [°] 32.9 38.4 43.1
Main Product Characteristics – OWI specific
(1)
Ocean Wind Field Spatial Resolution [km x km] 1x1
Ocean Wind Field Grid Dimension [azimuth cell x
170 x 250
ground range cell]
Main Product Characteristics – RVL specific
Radial Surface Velocity Spatial Resolution [km x 1)
2x2
km]
Radial Surface Velocity Grid Dimension [azimuth
85 x 125
cell x ground range cell]
Product Performance Parameters
Product Performance Parameters – OWI specific
Wind Speed [m/s]

Wind Direction [degN]

Product Performance Parameters – RVL specific

Radial Surface Velocity [m/s]

Doppler frequency [Hz]

Processing Parameters
Processing Parameters – OWI specific
Geophysical scattering model function CMOD-IFR2 NN or CMOD2-I3 NN
Polarization ratio model Mouche et al (1)
Data Volume for a 25s Long (approximately 170 km Azimuth Coverage) Product
Data Volume
Total Data Volume of Ocean Wind Field 3740000
Component [bytes]
Total Data Volume of Radial Surface Velocity 3146000
Component [bytes]
Total Data Volume of OCN Product [bytes] 6886000
Notes
(1) Product splits 170km x 250km IW image into 170x250 images of 1km x 1km for
OWI estimation.
Product splits 170km x 250km IW image into 85x125 images of 2km x 2km for
RVL estimation. Note that the spatial resolution is approximately twice the grid
spacing in the RVL product.

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8.3 Extra Wide Swath L2 Products Definition

8.3.1 Extra Wide Swath OCN Product Definition

Table 8-3 Extra Wide Swath OCN Product

Product ID EW_OCN
Product Type Extra Wide Swath Ocean
Main Product Characteristics
Coordinate System Ground Range (OWI and RVL)
Polarisation Options Single Dual Co-polarisation (HH or VV)
Beam ID EW1 EW2 EW3 EW4 EW5
Incidence angle [°] 23.7 30.9 36.2 40.9 44.5
Main Product Characteristics – OWI specific
(1)
Ocean Wind Field Spatial Resolution [km x km] 1x1
Ocean Wind Field Grid Dimension [azimuth cell x
400 x 400
ground range cell]
Main Product Characteristics – RVL specific
Radial Surface Velocity Spatial Resolution [km x 1)
4x4
km]
Radial Surface Velocity Grid Dimension [azimuth
100 x 100
cell x ground range cell]
Product Performance Parameters
Product Performance Parameters – OWI specific
Wind Speed [m/s]

Wind Direction [degN]

Product Performance Parameters – RVL specific

Radial Surface Velocity [m/s]

Doppler frequency [Hz]

Processing Parameters
Processing Parameters – OWI specific
Geophysical scattering model function CMOD-IFR2 NN or CMOD2-I3 NN
Polarization ratio model Mouche et al (1)
Data Volume for a 60s Long (approximately 400 km Azimuth Coverage) Product
Data Volume
Total Data Volume of Ocean Wind Field 14080000
Component [bytes]
Total Data Volume of Radial Surface Velocity 11842000
Component [bytes]
Total Data Volume of OCN Product [bytes] 25922000
Notes
(1) Product splits 400km x 400km EW image into 400x400 images of 1km x 1km for
OWI estimation.
Product splits 400km x 400km EW image into 100x100 images of 4km x 4km for
RVL estimation. Note that the spatial resolution is approximately twice the grid
spacing for the RVL product.

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8.4 Wave L2 Products Definition

8.4.1 Wave OCN Product Definition

Table 8-4 Wave OCN Product

Product ID WV_OCN
Product Type Wave Ocean
Main Product Characteristics
Coordinate System Ground Range (OSW, OWI and RVL)

Polarisation Options Single (HH or VV)

Beam ID WV1 WV2
Incidence angle [°] 23 36.5
Main Product Characteristics – OSW specific
4
Ocean Swell Spectra [m ]

2
Quality cross-spectra [m ]

Ocean Swell Spectra Spatial Resolution [km x km] 20x20

Ocean Swell Spectra Spectral Resolution [m] On average, between 30 and 220 m depending on wave direction relative
to azimuth direction
Ocean Swell Spectra Grid Dimension [cell] 1x1
Main Product Characteristics – OWI specific
Ocean Wind Field Spatial Resolution of [km x km] 20x20
Ocean Wind Field Grid Dimension [azimuth cell x 1x1
ground range cell]
Main Product Characteristics – RVL specific
Radial Surface Velocity Spatial resolution [km x km] 20x20
Radial Surface Velocity Grid Dimension [azimuth cell x 1x1
ground range cell]
Product Performance Parameters
Product Performance Parameters – OSW specific
Number of Wave Partitions 5
SAR Significant Waveheight [m] >0, RMSe < 0.5, Bias < 0.1
Dominant Wave Length [m]

Dominant Wave Direction [degN]

Azimuth Cut-off Wavelength [m]

Confidence Flag for Wave Direction Retrieval 0 or 1

Product Performance Parameters – OWI specific
Wind Speed [m/s]

Wind Direction [degN]

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Product ID WV_OCN
Product Performance Parameters – RVL specific
Radial Surface Velocity [m/s]

Doppler frequency [Hz]

Processing Parameters
Processing Parameters – OSW specific
Number of individual looks (range x azimuth) 1x3
Frequency separation of neighbouring looks [Hz]

Range Look Bandwidth [Hz]

Azimuth Look Bandwidth [Hz] 0.75 f PRF

Number of Pixels Used in Spectral Estimation [range, 256, 256
azimuth]
Low Pass Filter Width for Detrending of Image [m] 1000
Data Size & Volume for a 20 km Azimuth Coverage Product
Data Size & Volume
Number of Lines in Spectra 60
Number of Pixels per Line 72
Data Volume per Spectra [bytes] 17280
Total Data Volume of Ocean Swell Spectra Component 58000
[bytes]
Total Data Volume of Ocean Wind Field Component 90
[bytes]
Total Data Volume of Radial Surface Velocity 80
Component [bytes]
Total Data Volume of OCN Product [bytes] 58170

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9 AUXILIARY DATA FOR L1 PROCESSING

In order to generate Sentinel-1 L1 products, the Sentinel-1 IPF SAR processor

requires additional information not included in the data acquired from the satellite.
This information is provided in auxiliary data files that originate either within the
PDGS or from external sources.

The auxiliary data for Sentinel-1 L1 product processing can be grouped into the
following categories:
• Digital Elevation Model
• L1 Processor Parameters
• Calibration Data
• Instrument Parameters
• Orbit and Attitude Information

9.1 Digital Elevation Model (DEM)

DEMs are optionally used by the IPF to derive height information used when
processing L1 georeferenced products.

The IPF can use the following types of DEM:

• An internal coarse DEM (the National Geophysical Data Center TerrainBase
Global DTM, which provides a global coverage with a 5 arcminute spacing),
or
• A fine DEM provided externally.

The external DEMs supported by the IPF are those supported by the Earth Explorer
CFI.

Version 4.2 of the Earth Observation CFI, currently used by the IPF, supports the
Global Earth Topography And Sea Surface Elevation (GETASSE30) DEM, versions
1 and 2.

The GETASSE30 DEM is a composite of four other datasets: the SRTM30 data, the
Altimeter Corrected Elevations (ACE) DEM, the Mean Sea Surface (MSS) data and
the EGM96 ellipsoid. The resulting GETASSE30 DEM represents the earth
topography and sea surface elevation with respect to the WGS84 ellipsoid at 30 arc
second resolution.

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9.2 L1 Processor Parameters

The L1 Processor Parameters auxiliary data contains various parameters required by

the IPF for producing the L1 products with the desired properties, and the fine-
tuning of the processor and the selection of specific processing options. The L1
processor parameters auxiliary data is described in Document R-9.

9.3 Calibration Data

The most important component of the Calibration Data is the set of antenna patterns.
The antenna patterns are derived from pre-launch antenna measurements and after-
launch antenna model verification activities. The beam-to-beam gain offsets are
also derived through this process. The antenna patterns and beam-to-beam gain
offsets are used by the SAR processor for radiometric calibration. Details of the
Calibration Data are provided in [R-9].

9.4 Instrument Parameters

The Instrument Parameters auxiliary data includes mainly parameters either constant
over the mission or requiring infrequent updates, and is described in [R-9].

9.5 Orbit and Attitude Information

High-accuracy Orbit State Vectors (OSV) and attitude quaternions are available
within the Sentinel-1 downlink data and are provided on continuous basis and
updated at a specific frequency. After the data acquisition, precise orbit and attitude
determination data is reconstructed and made available to the IPF in the form of
orbit files containing OSV auxiliary data and attitude files containing attitude
quaternions auxiliary data. The IPF will use OSVs and attitude quaternions either
from the orbit/attitude files or the downlink, depending on the IPF parameters used
when processing a particular image.

Unlike the other auxiliary data described in the previous sections, which are static
and change infrequently over the lifetime of the mission, the orbit state vector
auxiliary data and the attitude quaternion auxiliary data will be updated frequently
as new orbit state vectors and attitude quaternions are produced.

Details of the Orbit and Attitude Information are provided in [R-9].

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10 AUXILIARY DATA FOR L2 PROCESSING

In order to generate Sentinel-1 L2 products, the Sentinel-1 IPF SAR processor

requires additional information not included in the data acquired from the satellite.
This information is provided in auxiliary data files that originate either within the
PDGS of from external sources.

The auxiliary data for Sentinel-1 L2 product processing can be grouped into the
following categories:
• ECMWF atmospheric model
• Simulated cross spectra data
• Sea ice data
• Wavewatch3 Stokes drift
• Excitation Coefficients Error Matrix
• L2 Processor parameters

10.1 ECMWF Atmospheric Model

Wind speed and direction at 10 m above the sea surface from the ECMWF
atmospheric model is required with spatial and temporal resolution of 0.125 degrees
every 3 hours. This is used for both OWI and OSW processing.

Details of the ECMWF Atmospheric Model are provided in Document [R-9].

10.2 Simulated Cross Spectra Data

The OSW processing algorithm requires simulated cross spectra look-up tables to
predict the modulation transfer function (MTF) and to remove non-linear effects
from the cross spectra. There is one look-up table for each swath and polarisation.
The basic content of the look-up table is the simulated cross-spectrum for a given
ocean swell spectrum, computed from the input wind speed, direction and inverse
wave age, and an estimate of the MTF for the given wind field:
• Simulated Cross-Spectra are computed for a wide range of wind speeds and
directions. The non-linear part of the cross-spectra is stored in the table.
• The real aperture MTF amplitude;
• The wind speed range array;
• The wind direction array;
• The inverse wave age array.

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The Simulated Cross Spectra Data is described in Document [R-9].

10.3 Sea Ice Data

Sea ice data is used by the OWI algorithm. Wind inversion processing is not
performed if sea ice coverage is greater than 10% in the imagette considered. This
percentage is directly given by the sea ice edge product delivered by the Ocean and
Sea Ice Satellite Application Facility (OSI SAF) at a spatial resolution of 10 km
every day. The product is available on the OSI SAF sea ice FTP server
(ftp://saf.met.no/prod/ice) in HDF5 and GRIB format and on the Marine
Environment and Security for the European Area (MERSEA) server
(http://www.mersea.eu.org).

Details of the Sea Ice Data are provided in Document [R-9].

10.4 Wavewatch3 Stokes Drift

The Wavewatch3 Stokes Drift file is used to interpret the RVL component of the
OCN product for all imaging modes.

The stokes drift is a vector calculated as the third order moment of the wave spectra.
This cannot be estimated from SAR wave spectra since the stokes drift is mostly
dependent on wind sea which is not imaged by SAR. Therefore this information has
to come from a model that has a good physical representation of the shorter waves.
Stokes drift forecast files in NetCDF format generated by the operational
Wavewatch3 model run at IFREMER will be used.

Details of the Wavewatch3 Stokes Drift are provided in Document [R-9].

10.5 Excitation Coefficients Error Matrix

The Excitation Coefficients Error Matrix is used by the RVL algorithm to derive the
accurate Doppler estimation by synthesising a radiation beam pattern using an
antenna model.

The Excitation Coefficients Error Matrix is a product of the Sentinel-1 RFC mode,
which is a specific calibration mode meant to assess the instrument health and
stability.

In particular, the RFC mode verifies the Tx and Rx excitation coefficients to ensure
the validity of the radiation beam patterns generated by the instrument. This is done
through the excitation coefficients error matrix product, which identifies changes in
the excitation coefficients with respect to reference values (e.g. pre-launch
reference).

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One excitation coefficients error matrix product is defined for polarisation H and
another one for polarisation V. Only the matrix matching the co-polarisation data is
used by the IPF:
• in case of single polarisation HH or dual polarisation HH/HV only the matrix
for polarisation H is used,
• in case of single polarisation VV or dual polarisation VV/VH only the matrix
for polarisation V is used.

Details of the Excitation Coefficients Error Matrix are provided in Document [R-9].

10.6 L2 Processor Parameters

The L2 Processor Parameters auxiliary data contains various parameters required by

the IPF for producing the L2 products with the desired properties, and the fine-
tuning of the processor and the selection of specific processing options. The
processor parameters auxiliary data is described in Document [R-9].

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A PRODUCT DESCRIPTION TERMINOLOGY

This section explains the terms used in the product definition tables included in
Section 7 and 8. As in the tables, the definitions have been grouped into four classes,
separately for L1 and L2 products:
1. Main product characteristics
2. Product performance parameters
3. SAR processing parameters
4. Data size and volume

A1 Level 1 Product Description Terminology

A1.1 Main Product Characteristics

A1.1.1 Coordinate System

Products can be represented in the slant range coordinate system (SLC products) or
in the ground range coordinate system (GRD products). See Section 4 for more
information.

The slant range and ground range represented products are produced in ‘zero-
Doppler’ orientation, i.e. with each row of pixels representing points along a line
perpendicular to the sub-satellite track.

A1.1.2 Bits per Pixel

A pixel can be represented by either a pair of integers (representing the real and
imaginary part (I and Q) of a complex number) or an unsigned integer (representing
the magnitude of a complex number). Therefore the number of bits per pixel is:
• (number of bits per integer) (for each I and Q) for complex products
• (number of bits per unsigned integer) for detected products.

The number of bits per integer (signed or unsigned) is 16 or 8.

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A1.1.3 Ground Range Coverage

The ground range coverage is the nominal range (across-track) dimension of the
area on the ground surface represented in the image. The azimuth (or along-track)
dimension of the image can be of any length and potentially as long as the
acquisition segment. For some calculations in the product definition, however, the
nominal length of each product has been defined to be equal to the ground range
coverage.

A1.1.4 Resolution

The spatial resolution of an imaging system is a measure of its ability to distinguish

between adjacent targets. The spatial resolution is defined as the Impulse Response
Function width (IRW) measured at 3 dB (half of the intensity) below the peak value,
in either range or azimuth direction.

The Impulse Response Function (IRF) (or the point target response) of a SAR
system (sensor and processor) is the 2-D image of a point target in either slant range
or ground range representation, neglecting effects of background clutter and thermal
noise.

The intensity of the IRF is significant mainly along the range and azimuth directions
and therefore, 1-D slices in range and azimuth, are used to characterize the 2-D IRF.

A1.1.5 Pixel Spacing

Pixel Spacing is the distance between adjacent pixels in an image measured in

metres. This is the same as the pixel size. The pixel spacing may be different for
range and azimuth. Range pixel spacing may be stated in slant range distance for
SLC products or in ground range distance for GRD products.

Typically, for complex-valued images, the pixel spacing in each dimension of the
image is similar in magnitude to the resolution in that dimension. For detected
images, the pixel spacing in each dimension is similar in magnitude to half the
resolution in that dimension. In order for the full information content of the image
to be retained, the pixel spacing must meet the Nyquist criterion. To meet this
criterion, the spatial sampling rate must exceed the bandwidth of the spatial
frequency content in the image.

A1.1.6 Incidence Angle

The incidence angle is the angle between the incident SAR beam and the axis
perpendicular to the local geodetic ground surface. The values provided in Section 7

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are nominal in that they are calculated assuming that the local surface follows the
ellipsoid, without any adjustment for the terrain height.

For Sentinel-1, the off-nadir angles, and implicitly the incidence angles, vary with
position of the satellite in orbit due to the roll steering law (as described in Section
3.2.3.2). The incidence angle values specified in each product table represent, for
each beam, the approximate incidence angle at mid swath and averaged over the
orbit.

The precise off-nadir and incidence angle ranges corresponding to the minimum and
maximum orbit height are shown in Table 3-3, Table 3-5, Table 3-7 and Table 3-9.

A1.1.7 Equivalent Number of (Independent) Looks (ENL)

The image speckle statistics for areas of distributed target are determined by the
multi-looking used in image generation. The equivalent number of independent
looks (ENL) for a given product type is intended to correspond to the number of
equally-weighted, statistically independent looks which would produce the same
speckle statistics as the processing used to generate the product.

For a distributed target (large enough to ensure statistical accuracy) in a perfectly

homogeneous area of a SAR image generated using NL equal, independent looks:

where µ and σ are respectively the mean and the standard deviation of signal power
over the distributed target. This ratio is therefore used to define the equivalent
number of independent looks for the general case (non-independent looks):

The ENL will normally be less than the total number of looks, NL, because of partial
overlapping of the looks and unequal weighting.

A1.1.8 Radiometric Resolution

The radiometric resolution is a measure of the ability to distinguish between uniform

distributed targets with different backscattering coefficient. It is measured on a
homogeneous distributed target, large enough to ensure statistical accuracy:

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A1.2 Product Performance Parameters

A1.2.1 Peak Side Lobe Ratio (PSLR)

The peak side lobe ratio is the worst-case measure of the SAR ability to identify a
weak target from a nearby strong target. The PSLR is defined as the ratio of the peak
intensity in the main-lobe of the IRF to the peak intensity of the most intense side-
lobe over 10 times the 3dB-IRW in each azimuth and range direction.

A1.2.2 Integrated Side-Lobe Ratio (ISLR)

The ISLR characterizes the SAR ability to detect weak targets in the neighbourhood
of strong targets. The ISLR is defined as the ratio of energy within the main-lobe of
the IRF (defined as lying within a rectangle of size 2x and 2y centered on the peak,
where x and y are the 3dB widths in range and azimuth) and the energy outside of
this area integrated over a region bounded by sides 10 times longer.

A1.2.3 2D Distributed Target Ambiguity Ratio (2D-DTAR)

The unambiguous zone in defined, in the range direction by the nominal swath
width and in the azimuth direction by the total processed Doppler bandwidth. An
ambiguous zone is defined as a region outside the unambiguous zone.

The 2D Distributed Target Ambiguity Ratio (2D-DTAR) is the ratio of energy

contribution from a distributed target in the unambiguous zone to the energy
contribution from a distributed target located in the unambiguous zone.

The ratio is to be calculated using the Distributed Target Radar Cross Section
Reference Model P’T/ΣPA, where:
P’T is the intensity of the radar response to a distributed target located within
the unambiguous zone, and
ΣPA is the summed intensity of the radar responses to the respective
distributed targets within the various ambiguous zones.

A1.2.4 Point Target Ambiguity Ratio (PTAR)

The Point Target Ambiguity Ratio is specified as the ratio PT / PA, where:
• PT is the peak intensity of the radar response to a point target located within
unambiguous zone

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• PA is the peak intensity of the radar response to a point target of the same
radar cross-section as defined for PT but located within the worst ambiguous
zone. The PTAR can be defined in both the range and azimuth directions.

A1.2.5 Noise Equivalent Sigma Zero (NESZ)

The Noise Equivalent Sigma Zero (NESZ) is a measure of the sensitivity of the
radar to areas of low backscatter. The NESZ is defined as the backscatter coefficient
σo (back-scattering cross section of a distributed target per unit area) of a distributed
target within the product coverage for which the signal power level in the final
image is equal to the noise power level (thermal noise only), i.e. an image SNR of 0
dB.

A1.2.6 Channel Co-registration Accuracy

The channel co-registration accuracy is a characteristic of the dual-polarisation

products and it represents the difference between the location of the same point
target in the two images, in either range or azimuth.

A1.2.7 Absolute Radiometric Accuracy

For a distributed target, the radiometric accuracy is defined as the 3σ deviation

resulting from measurement of σ0 of a homogeneous distributed target situated
anywhere in the operating dynamic range of the system, anywhere in the swath,
anywhere in time, and ignoring speckle.

For a point target, the radiometric accuracy is defined as the 3σ deviation of the
measurement of the radar cross-section with respect to the true radar cross section,
of a sufficiently bright target situated anywhere in the swath, anywhere in time.

The absolute radiometric accuracy accounts for all causes (including all errors from
calibration devices, processing and channel imbalance in case of polarimetric
products).

A1.2.8 Relative Radiometric Accuracy

The relative radiometric accuracy is the 3σ deviation that result form measuring the
radar cross-section of equivalent targets at the same time at different locations
within a product coverage. This includes stability effects within the time needed for
the acquisition of the product.

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A1.2.9 Absolute Location Accuracy

The pixel location accuracy is specified as the 3σ deviation in the estimate of the
position of a point target of sufficiently large cross-section, the estimate being the
point equidistant between the –3dB points of its detected impulse response measured
in along-track and across-track directions.

If the pixel location error depends on location within the image, the worst-case
location is applicable.

The values in the table assume that the Earth’s surface follows the shape of the
ellipsoid at a local specified elevation height. The use of ground truth data is not
included.

A1.3 SAR Processing Parameters

A1.3.1 Number of Range Looks

The number of range looks is the number of distinct or overlapping coherently

processed looks extracted from the pulse bandwidth which are combined after
detection to form the image.

A1.3.2 Number of Azimuth Looks

The number of azimuth looks is the number of distinct or overlapping coherently

processed looks extracted from the Doppler spectrum which are combined after
detection to form the image.

A1.3.3 Look Overlap

The look overlap is specified as the ratio between the size of the overlap between
any 2 nearby looks and the size of the look.

A1.3.4 Range Look Bandwidth

The range look bandwidth is the bandwidth of the segment of the total pulse
bandwidth which is coherently processed for each individual range look.

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Sentinel-1 MPC Ref:
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Date: 25/03/2016

A1.3.5 Azimuth Look Bandwidth

For Stripmap type modes, the azimuth look bandwidth is the processed Doppler
bandwidth for each individual azimuth look.

For TOPSAR modes, this parameter is the Doppler bandwidth of the signal from any
given target within the set of samples used for each look.

A1.3.6 Hamming Window Coefficient

In the SAR processor, both the range and azimuth spectrum of the data are weighted
by a (generalized) Hamming window defined by the (beam-dependent) coefficient
specified for each product table. The Hamming window is defined by

where a is the Hamming window coefficient.

The weighting has opposite effects on resolution and side lobes level therefore the
coefficient is chosen in such a way as to realize the desired trade-off between these
IPF characteristics. Table A-1 lists the propertied of the Hamming windows applied
in the Sentinel-1 SAR processor, as defined by the coefficient specified in the
product tables:

Table A-1 Hamming Window Properties

Hamming Window IRW Broadening PSLR [dB] ISLR [dB]

Coefficient Factor

0.52 1.54 -36.22 -37.39

0.6 1.32 -31.6 -26.18
0.61 1.3 -30.34 -25.22
0.62 1.28 -29.26 -24.35
0.63 1.27 -28.33 -23.55
0.65 1.24 -26.79 -22.07
0.70 1.18 -24.07 -19.10
0.72 1.16 -23.27 -18.10
0.73 1.15 -22.55 -17.63
0.75 1.13 -21.22 -16.75

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Date: 25/03/2016

A1.4 Data Size and Volume

This section introduces the definitions of the number of lines, number of pixels and
volume of an image.

A1.4.1 Number of Lines

The number of lines is calculated as follows:

Lines = (Image Azimuth Extent) / (Azimuth Pixel Spacing)

Note that for IW/EW, a small margin is included, to account for overlapping
between bursts and interleaving blank lines.

The number of lines in the tables in Section 7 is approximate and corresponds to the
specified azimuth dimension of the product (approximately equal to the ground
range coverage). It is rounded up to the nearest hundred.

A1.4.2 Number of Pixels per Line

The number of pixels is calculated as:

PixelsPerLine = (Image Range Extent) / (Range Pixel Spacing)

For SLC products, Image Range Extent represents the slant range image extent.

The number of pixels in the tables in Section 7 is approximate and rounded up to the
nearest hundred.

A1.4.3 Product Volume

The nominal product volume is calculated as follows:

Volume = PixelsPerLine * Lines * BitsPerPixel

The size of the annotations attached to the image is not included in the volume
figure.

Where products may contain data for more than one polarisation, the value stated in
the product definition table is given per polarisation channel.

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Date: 25/03/2016

A2 Level 2 Product Description Terminology

A2.1 Main Product Characteristics

A2.1.1 Coordinate System

The coordinate system for the two-dimensional wave spectrum in the OSW
component is a log-polar grid.

Scalar parameters including the RVL and OWI estimates are given as geolocated
measurements.

A2.1.2 Incidence Angle

The incidence angle for L2 products has the same meaning as for L1 products. Refer
to Section A1.1.6.

A2.1.3 Spatial Resolution

The spatial resolution is the size of the area [km2] on the ground from which the L2
product is derived.

For WV this is equal to the vignette size (20kmx20km).

For SM, the spatial resolution is the size of the nominal SM SLC (80kmx80km)
divided 4x4 for a 20km x 20km resolution for the ocean swell spectra, and higher for
the wind field and the radial surface velocity, typically 1km x 1km and 5km x 5km
respectively.

For the EW and IW modes, the approach is similar to SM; the typical spatial
resolution for the wind field and radial surface velocity is similar to the SM case.

A2.1.4 Ocean Swell Spectra Spectral Resolution

The spectral resolution of an ocean swell spectra cell is the shortest ocean
wavelength [m] (or longest ocean wavenumber [rad/m]) that can be detected. For a
SAR image, this depends on the sea state and the wave direction relative to azimuth.
This parameter is a vector of wave lengths equal to the number of directional bins.
In range, the theoretical limit is given by the range bandwidth, and does not depend
on the sea state.

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where λmin = 2π is the shortest wavelength in the spectra. Here λc is the

k max
azimuth cut-off wavelength estimated from the SAR image spectra, and ϕtrack is the
satellite track heading counter clockwise relative to North. This vector will be
provided for each wave cell.

A2.1.5 Ocean Swell Spectra Grid Dimension

The ocean swell spectra grid dimension is the number of 2D SAR wave spectra cells
in the range and azimuth direction. The spatial resolution in combination with the
L1 image size defines the OSW grid dimensions.

A2.1.6 Ocean Wind Field Grid Dimension

The ocean wind field grid dimension is the number of SAR wind cells in the range
and azimuth direction. The spatial resolution in combination with the L1 image size
defines the ocean wind field grid dimensions.

A2.1.7 Radial Surface Velocity Grid Dimension

The radial velocity grid dimension is the number of radial surface velocity cells in
the range and azimuth direction. The spatial resolution in combination with the L1
image size defines the radial surface velocity field grid dimensions.

A2.2 Product Performance Parameters

A2.2.1 Wind Speed

Wind speed is the ocean surface wind speed (at a height of 10 m above the ocean
surface) given in [m/s] derived from the SAR (L1 product) data. The quality of the
wind speed estimate depends on the NESZ and the calibration accuracy. This
parameter is provided for each ocean wind field cell.

A2.2.2 Wind Direction

The wind direction is the direction of the wind at a height of 10 m above the ocean
surface [degN, i.e. degrees clockwise from north], derived from the SAR data in

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Date: 25/03/2016

combination with or provided by an external source (ECMWF wind direction). This

parameter is provided for each ocean wind field cell.

A2.2.3 Doppler Frequency

The Doppler frequency [Hz] is estimated from the SLC data based on fitting the
azimuth spectral profile of the data to the antenna model taking into account additive
noise, aliasing, and side band effects. The Doppler frequency is used to retrieve an
estimate of the radial surface velocity, after first removing the contribution to the
Doppler from geometry and mispointing errors.

A2.2.4 Radial Surface Velocity

The radial surface velocity [m/s] is derived from the L2 Doppler grid using the
difference of the L2 Doppler grid and the geometrical Doppler from L1. The radial
surface velocity can be used to derive the radial component of the ocean surface
current field. It is provided on the radial surface velocity grid.

A2.2.5 Number of Wave Partitions

The number of wave partitions is the number of independent wave systems the two-
dimensional wave spectra (OSW) consist of. Typically this is a swell wave spectrum
and wind sea wave spectrum. The default number of wave partitions is 5.

A2.2.6 SAR Significant Waveheight

The SAR significant waveheight is the significant waveheight computed from the
OSW within the product [m] for the five most energetic wave partitions. This
parameter is provided for each ocean swell spectra cell, and resampled into the
ocean wind field grid.

A2.2.7 Dominant Wave Length

The dominant wave length is the dominant wavelength of the swell wave spectra
[m] for the five most energetic wave partitions. This parameter will be provided for
each ocean swell spectra cell and resampled into the ocean wind field grid.

A2.2.8 Dominant Wave Direction

The dominant wave direction is the dominant wave direction of the swell wave
spectra [degN] for the five most energetic wave partitions. This parameter will be

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Date: 25/03/2016

provided for each ocean swell spectra cell and resampled into the ocean wind field
grid.

A2.2.9 Azimuth Cut-off Wavelength

The cut-off wavelength is the shortest wavelength in the azimuth direction [m] that
is resolved in the ocean swell spectra. The azimuth cut-off wavelength is computed
from the SAR imagette cross-spectra. The Spectral Resolution is derived from this
parameter. The azimuth cut-off will increase with incidence angle because it is
proportional to the range-to-velocity ratio. It also depends on the sea-state. This
parameter is provided for each ocean swell spectra cell.

A2.2.10 Confidence Flag for Wave Direction Retrieval

The confidence flag for wave direction retrieval is the confidence of wave direction
retrieval, for the five most energetic wave partitions [0, 1, 2, 3 or 4]. When this
parameter is set to 0 the wave direction is resolved without 180 degree ambiguity,
else it is set to 1. This parameter is provided for each ocean swell spectra cell, and
resampled into the ocean wind field grid.

A2.2.11 Normalised Radar Cross Section

This is the normalized radar cross-section (NCRS) of the sub-image [dB]. The
NRCS is used in the wind retrieval algorithm, and is also directly related to the dc-
component of the image spectra. This parameter is provided for each wind field grid
cell.

A2.2.12 Wave Age

The wave age is the ratio of wave velocity to wind velocity, and describes the
saturation of the wave spectra [non-dimensional]. The wave age is an outcome of the
OSW retrieval, and is provided on the wave grid cell.

A2.2.13 Signal-to-Noise Ratio

The signal-to-noise ratio is the spectral peak to noise ratio of the OSW product, and
is used for setting the confidence of the wave retrieval. It is provided for the five
most energetic partitions, and is given on the wave grid cell.

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Date: 25/03/2016

A2.2.14 Normalized Image Variance

The normalized image variance is the sub-image variance normalized with mean
imagette intensity. It is provided on the wind grid cell.

A2.3 Processing Parameters

A2.3.1 Number of Individual Looks

The number of individual looks is the number of independent looks in range and
azimuth extracted from the input SLC data by the OSW algorithm for the spectral
estimation.

A2.3.2 Frequency Separation of Neighbouring Looks

The frequency separation between neighbouring, looks gives the inter look
separation time by the formula:

This is typically around 0.25 sec.

A2.3.3 Range Look Bandwidth

The range look bandwidth used during OSW processing is related to the instrument
range sampling frequency (SF) as 0.78 SF.

A2.3.4 Azimuth Look Bandwidth

The azimuth look bandwidth used during the OSW processing refers to the
individual look bandwidth. This is related to the instrument pulse repetition
frequency (PRF) by default as 0.75  PRF.

A2.3.5 Number of Pixels Used in Spectral Estimation

This is the number of pixels used in each periodogram, and thus specifies the
spectral bin size of the Cartesian image spectrum. Default is 5012x512 pixels.

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Date: 25/03/2016

A2.3.6 Low Pass Filter Width for Detrending of Image

This is a filter that removes long wavelength non-wave features from the original
input image in the spatial domain. Default is 1000m.

A2.3.7 Geophysical Scattering Model Function

The geophysical scattering model function is a model function (semi-empirical,

empirical, or theoretical) that predicts the normalized radar cross-section for a given
wind field and radar imaging parameters and geometry.

A2.3.8 Polarization Ratio Model

The polarization ratio model is a model function that relates the normalized radar
cross-section of different polarizations. It is mainly used to convert the normalized
radar cross-section of VV polarization into HH polarization.

A2.4 Data Size and Volume

This section introduces the definitions of the number of lines, number of pixels and
volume of an L2 product.

A2.4.1 Number of Lines

This is the number of estimates in the azimuth direction.

A2.4.2 Number of Pixels per Line

This is the number of estimates in the range direction.

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Date: 25/03/2016

A2.4.3 Product Volume

The nominal product volume is calculated as follows:

Volume = ( PixelsPerLine(OSW) * Lines(OSW) * BitsPerPixel(OSW) ) +
( PixelsPerLine(OWI) * Lines(OWI) * BitsPerPixel(OWI) ) +
( PixelsPerLine(RVL) * Lines(RVL) * BitsPerPixel(RVL) ) +

The size of the annotations attached to the image is not included in the volume
figure.

Where products may contain data for more than one polarisation, the value stated in
the product definition table is given per polarisation channel.

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Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
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Date: 25/03/2016

B DETAILED SAR PERFORMANCE

In this appendix details of some of the main Sentinel-1 Level 1 SAR performance
parameters are provided. In particular, for each acquisition mode, the graphs of the
variation within each swath of the ground range resolution, range DTAR and NESZ
are presented.

The ground range resolution graphs are provided for the SLC products as well as for
all standard GRD products. They are based on the detailed derivation of the Level 1
product characteristics provided in Appendix C.

The range DTAR and NESZ performance are provided for the SLC products. For
the GRD products, the range DTAR and NESZ performance are very similar. Minor
differences area function of slightly different processing window coefficients and
the GRD look overlap. Note that the current graphs correspond to the space
segment SLC definition and are based on [A-3]. The actual graphs are TBD and will
be included in a future version of this document.

Note that, in theory, the NESZ profiles present a slight dependency on polarisation
through the (simulated) sub-array patterns used to compute the overall antenna
pattern. However, the difference between co- and cross-polarisation is less than 0.1
dB on the main-lobe of the overall elevation pattern. This would cause the co- and
cross polarisation NESZ plots to appear totally overlapped on the graphs. Therefore,
for each beam, the NESZ profile for only one polarisation (the worst case) was
represented.

When the actual measured embedded row patterns, both in elevation and azimuth,
will be available, the graphs will be updated (TBD) if a more significant difference
between polarizations is identified.

Due to the variation of the off-nadir angle (and implicitly incidence angle) induced
by the roll steering law (as presented in Section 3.2.3.2) the parameters described in
this appendix vary with respect to the position of the satellite along the orbit. To
reflect this variation, two instances of each graph are provided: at minimum orbit
altitude (~ 698 km) and at maximum orbit altitude (~ 726 km).

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Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
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Date: 25/03/2016

B1 SM Mode

This section provides the following graphs:

• Variation of the SM near and far range incidence angles along the orbit
• Ground range resolution of the SM_SLC, SM_GRD_FR, SM_GRD_HR and
SM_GRD_MR products at minimum and maximum orbit altitude
• Range DTAR performance of the SM_SLC product
• NESZ performance of the SM_SLC product

S1 near
S2 near
S3 near
S4 near
S5 near
S6 near

Figure B-1 Variation of the Near Range Incidence Angle along the Orbit for SM Mode

S1 far
S2 far
S3 far
S4 far
S5 far
S6 far

Figure B-2 Variation of the Far Range Incidence Angle along the Orbit for SM Mode

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Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
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Date: 25/03/2016

Ground Range Resolution of the SM_SLC Product at Minimum Altitude

5.6
5.4
Ground Range Resolution [m]

5.2

5.0 S1
S2
4.8
S3
4.6
S4
4.4
S5
4.2 S6
4.0
3.8

3.6
15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Incidence Angles [deg]

Figure B-3 Ground Range Resolution of the SM_SLC Product at Minimum Altitude

Ground Range Resolution of the SM_SLC Product at Maximum Altitude

5.6
5.4
Ground Range Resolution [m]

5.2
S1
5.0
S2
4.8
S3
4.6
S4
4.4
S5
4.2
S6
4.0
3.8
3.6
15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Incidence Angles [deg]

Figure B-4 Ground Range Resolution of the SM_SLC Product at Maximum Altitude

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Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
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Date: 25/03/2016

Ground Range Resolution of the SM_GRD_FR Product at Minimum Altitude

10.5
10.1
Ground Range Resolution [m]

9.7
S1
9.3
S2
9.0
S3
8.6
S4
8.2
S5
7.8
S6
7.4
7.0
6.7
15 20 25 30 35 40 45 50
Incidence Angles [deg]

Figure B-5 Ground Range Resolution of the SM_GRD_FR Product at Minimum Altitude

Ground Range Resolution of the SM_GRD_FR Product at Maximum Altitude

10.5
Ground Range Resolution [m]

10.1
9.7
S1
9.3
S2
9.0
S3
8.6
S4
8.2
S5
7.8
S6
7.4
7.0
6.7
15 20 25 30 35 40 45 50
Incidence Angles [deg]

Figure B-6 Ground Range Resolution of the SM_GRD_FR Product at Maximum Altitude

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Issue/Revision:
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Date: 25/03/2016

Ground Range Resolution of the SM_GRD_HR Product at Minimum Altitude

27.3
26.3
Ground Range Resolution [m]

25.3
S1
24.2
S2
23.2
S3
22.2
S4
21.2
S5
20.2
S6
19.1
18.1
17.1
15 20 25 30 35 40 45 50
Incidence Angles [deg]

Figure B-7 Ground Range Resolution of the SM_GRD_HR Product at Minimum Altitude

Ground Range Resolution of the SM_GRD_HR Product at Maximum Altitude

27.3
Ground Range Resolution [m]

26.3
25.3
S1
24.2
S2
23.2
S3
22.2
S4
21.2
S5
20.2
S6
19.1
18.1
17.1
15 20 25 30 35 40 45 50
Incidence Angles [deg]

Figure B-8 Ground Range Resolution of the SM_GRD_HR Product at Maximum Altitude

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Issue/Revision:
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Date: 25/03/2016

Ground Range Resolution of the SM_GRD_MR Product at Minimum Altitude

99.8
96.2
Ground Range Resolution [m]

92.7
S1
89.2
S2
85.7
S3
82.2
S4
78.7
S5
75.1
S6
71.6
68.1
64.6
15 20 25 30 35 40 45 50
Incidence Angles [deg]

Figure B-9 Ground Range Resolution of the SM_GRD_MR Product at Minimum Altitude

Ground Range Resolution of the SM_GRD_MR Product at Maximum Altitude

99.8
Ground Range Resolution [m]

96.2
92.7
S1
89.2
S2
85.7
S3
82.2
S4
78.7
S5
75.1
S6
71.6
68.1
64.6
15 20 25 30 35 40 45 50
Incidence Angles [deg]

Figure B-10 Ground Range Resolution of the SM_GRD_MR Product at Maximum

Altitude

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Date: 25/03/2016

Range DTAR Performance of the SM_SLC Product at Minimum Altitude S1 VV

S1 VH
S2 VV
S2 VH
-20
S3 VV
RANGE DTAR [dB]

-25 S3 VH
-30 S4 VV
S4 VH
-35
S5 VV
-40 S5 VH

-45 S6 VV
S6 VH
-50
-55
16 18 20 22 24 26 28 30 32 34 36 38 40 42
Off-Nadir angles [deg]

Figure B-11 Range-DTAR Performance of the SM_SLC Product at Minimum Altitude

Range DTAR Performance of the SM_SLC Product at Maximum Altitude S1 VV

S1 VH
S2 VV
S2 VH
-20
S3 VV
RANGE DTAR [dB]

-25 S3 VH
-30 S4 VV
S4 VH
-35
S5 VV
-40 S5 VH
-45 S6 VV
-50 S6 VH

-55
16 18 20 22 24 26 28 30 32 34 36 38 40 42
Off-Nadir angles [deg]

Figure B-12 Range-DTAR Performance of the SM_SLC Product at Maximum Altitude

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Date: 25/03/2016

NESZ Performance of the SM_SLC product at Minimum Altitude

-21.0

-23.0

S1
-25.0
S2
NESZ [dB]

S3
-27.0
S4
S5
-29.0
S6

-31.0

-33.0
15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
Incidence Angles [deg]

Figure B-13 NESZ Performance of the SM_SLC Product at Minimum Altitude

NESZ Performance of the SM_SLC product at Maximum Altitude

-21.0

-23.0

S1
-25.0
S2
NESZ [dB]

S3
-27.0
S4
S5
-29.0
S6

-31.0

-33.0
15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Incidence Angles [deg]

Figure B-14 NESZ Performance of the SM_SLC Product at Maximum Altitude

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Date: 25/03/2016

B2 IW Mode

This section provides the following graphs:

• Variation of the IW near and far range incidence angles along the orbit
• Ground range resolution of the IW_SLC, IW_GRD_HR and IW_GRD_MR
products at minimum and maximum orbit altitude
• Range DTAR performance of the IW_SLC product, at minimum and
maximum orbit altitude
• NESZ performance of the IW_SLC product, at minimum and maximum orbit
altitude

IW1 near
IW2 near
IW3 near

Figure B-15 Variation of the Near Range Incidence Angle along the Orbit for IW Mode

IW1 far
IW2 far
IW3 far

Figure B-16 Variation of the Far Range Incidence Angle along the Orbit for IW Mode

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Date: 25/03/2016

Ground Range Resolution of the IW_SLC Product at Minimum Altitude

5.6

5.4
Ground Range Resolution [m]

5.2

5.0 IW1
IW2
4.8 IW3

4.6

4.4

4.2
28 30 32 34 36 38 40 42 44 46
Incidence Angles [deg]

Figure B-17 Ground Range Resolution of the IW_SLC Product at Minimum Altitude

Ground Range Resolution of the IW_SLC Product at Maximum Altitude

6.3
Ground Range Resolution [m]

5.8

5.3
IW1
IW2
4.8 IW3

4.3

3.8
28 30 32 34 36 38 40 42 44 46
Incidence Angles [deg]

Figure B-18 Ground Range Resolution of the IW_SLC Product at Maximum Altitude

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Date: 25/03/2016

Ground Range Resolution of the IW_GRD_HR Product at Minimum Altitude

24.1

23.1
Slant Range Resolution [m]

22.1

21.1 IW1
IW2
20.1 IW3

19.1

18.1

17.1
28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Incidence Angles [deg]

Figure B-19 Ground Range Resolution of the IW_GRD_HR Product at Minimum Altitude

Ground Range Resolution of the IW_GRD_HR Product at Maximum Altitude

24.1

23.1
Slant Range Resolution [m]

22.1

21.1 IW1
IW2
20.1 IW3

19.1

18.1

17.1
28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Incidence Angles [deg]

Figure B-20 Ground Range Resolution of the IW_GRD_HR Product at Maximum

Altitude

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Date: 25/03/2016

Ground Range Resolution of the IW_GRD_MR Product at Minimum Altitude

104.0
101.2
Slant Range Resolution [m]

98.4
95.6

92.8 IW1
90.1 IW2
87.3 IW3

84.5
81.7

79.0
76.2
28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Incidence Angles [deg]

Figure B-21 Ground Range Resolution of the IW_GRD_MR Product at Minimum

Altitude

Ground Range Resolution of the IW_GRD_MR Product at Maximum Altitude

104.0

101.2
Slant Range Resolution [m]

98.4

95.6

92.8 IW1
90.1 IW2
87.3 IW3

84.5

81.7

79.0
76.2
28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Incidence Angles [deg]

Figure B-22 Ground Range Resolution of the IW_GRD_MR Product at Maximum

Altitude

ESA Unclassified – For Official Use

B-12
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Range DTAR Performance of the IW_SLC Product at Minimum Altitude

-20
RANGE DTAR [dB]

-25
IW1 VV

-30 IW1 VH

IW2 VV

-35 IW2 VH

IW3 VV

-40 IW3 VH

-45
25 27 29 31 33 35 37 39 41
Off-Nadir Angles [deg]

Figure B-23 Range DTAR Performance of the IW_SLC Product at Minimum Altitude

Range DTAR Performance of the IW_SLC Product at Maximum Altitude

-20
RANGE DTAR [dB]

-25
IW1 VV

-30 IW1 VH

IW2 VV
-35 IW2 VH

IW3 VV
-40
IW3 VH

-45
25 27 29 31 33 35 37 39 41
Off-Nadir Angles [deg]

Figure B-24 Range DTAR Performance of the IW_SLC Product at Maximum Altitude

ESA Unclassified – For Official Use

B-13
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

NESZ Performance of the IW_SLC product at Minimum Altitude

-21.0

-22.0

-23.0

-24.0

-25.0
NESZ [dB]

IW1
-26.0 IW2
IW3
-27.0

-28.0

-29.0

-30.0

-31.0
29 31 33 35 37 39 41 43 45 47
Incidence Angles [deg]

Figure B-25 NESZ Performance of the IW_SLC Product at Minimum Altitude

NESZ Performance of the IW_SLC product at Maximum Altitude

-21.0

-22.0

-23.0

-24.0

-25.0
NESZ [dB]

IW1
-26.0 IW2
IW3
-27.0

-28.0

-29.0

-30.0

-31.0
29 31 33 35 37 39 41 43 45 47
Incidence Angles [deg]

Figure B-26 NESZ Performance of the IW_SLC Product at Maximum Altitude

ESA Unclassified – For Official Use

B-14
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

B3 EW Mode

This section provides the following graphs:

• Variation of the EW near and far range incidence angles along the orbit
• Ground range resolution of the EW_SLC, EW_GRD_HR and EW_GRD_MR
products, at minimum and maximum orbit altitude
• Range DTAR performance of the EW_SLC product, at minimum and
maximum orbit altitude
• NESZ performance of the EW_SLC product, at minimum and maximum orbit
altitude

Near Range Incidence along Orbit for EW beams

50.00
45.00
Incidence angle [deg]

40.00
EW1 near
35.00 EW2 near
EW3 near
30.00 EW4 near
EW5 near
25.00
20.00
15.00
-90.00 -40.00 10.00 60.00
Latitude [deg]

Figure B-27 Variation of the Near Range Incidence Angle along the Orbit for EW Mode

Far Range Incidence along Orbit for EW beams

50.00
Incidence angle [deg]

45.00
40.00
EW1 far
35.00 EW2 far
EW3 far
30.00 EW4 far
EW5 far
25.00
20.00
15.00
-90.00 -40.00 10.00 60.00
Latitude [deg]

Figure B-28 Variation of the Far Range Incidence Angle along the Orbit for EW Mode

ESA Unclassified – For Official Use

B-15
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Ground Range Resolution of the EW_SLC Product at Minimum Altitude

25.0
Ground Range Resolution [m]

23.0
EW1
EW2
21.0
EW3
EW4
19.0
EW5

17.0

15.0
15 20 25 30 35 40 45 50
Incidence Angles [deg]

Figure B-29 Ground Range Resolution of the EW_SLC Product at Minimum Altitude

Ground Range Resolution of the EW_SLC Product at Maximum Altitude

25.0
Ground Range Resolution [m]

23.0
EW1
EW2
21.0
EW3
EW4
19.0
EW5

17.0

15.0
15 20 25 30 35 40 45 50
Incidence Angles [deg]

Figure B-30 Ground Range Resolution of the EW_SLC Product at Maximum Altitude

ESA Unclassified – For Official Use

B-16
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Ground Range Resolution of the EW_GRD_HR Product at Minimum Altitude

67.2
64.3
Slant Range Resolution [m]

61.4
EW1
58.4
EW2
55.5 EW3
52.6 EW4
49.7 EW5
46.8
43.8
40.9
38.0
15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
Incidence Angles [deg]

Figure B-31 Ground Range Resolution of the EW_GRD_HR Product at Minimum

Altitude

Ground Range Resolution of the EW_GRD_HR Product at Maximum Altitude

67.2

64.3
Slant Range Resolution [m]

61.4

58.4
EW1
55.5 EW2
52.6 EW3
49.7 EW4
EW5
46.8

43.8

40.9
38.0
15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Incidence Angles [deg]

Figure B-32 Ground Range Resolution of the EW_GRD_HR Product at Maximum

Altitude

ESA Unclassified – For Official Use

B-17
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Ground Range Resolution of the EW_GRD_MR Product at Minimum Altitude

120.3
115.3
Slant Range Resolution [m]

110.3
EW1
105.3
EW2
100.3
EW3
95.3
EW4
90.3
EW5
85.3
80.3
75.3
70.3
15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
Incidence Angles [deg]

Figure B-33 Ground Range Resolution of the EW_GRD_MR Product at Minimum

Altitude

Ground Range Resolution of the EW_GRD_MR Product at Maximum Altitude

120.3
115.3
Slant Range Resolution [m]

110.3
105.3 EW1

100.3 EW2

95.3 EW3
EW4
90.3
EW5
85.3
80.3
75.3
70.3
15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47
Incidence Angles [deg]

Figure B-34 Ground Range Resolution of the EW_GRD_MR Product at Maximum

Altitude

ESA Unclassified – For Official Use

B-18
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Range DTAR Performance of the EW_SLC Product at Minimum Altitude

-25
EW1 VV
RANGE DTAR [dB]

EW1 VH
-30
EW2 VV
EW2 VH
-35
EW3 VV
EW3 VH
-40
EW4 VV
EW4 VH
-45
EW5 VV
EW5 VH
-50
15 17 19 21 23 25 27 29 31 33 35 37 39 41 43
Off-Nadir Angles [deg]

Figure B-35 Range-DTAR Performance of the EW_SLC Product at Minimum Altitude

Range DTAR Performance of the EW_SLC Product at Maximum Altitude

-25
EW1 VV
RANGE DTAR [dB]

-30 EW1 VH
EW2 VV

-35 EW2 VH
EW3 VV
EW3 VH
-40
EW4 VV
EW4 VH
-45 EW5 VV
EW5 VH
-50
15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45
Off-Nadir angles [deg]

Figure B-36 Range-DTAR Performance of the EW_SLC Product at Maximum Altitude

ESA Unclassified – For Official Use

B-19
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

NESZ Performance of the EW_SLC product at Minimum Altitude

-22.0

-24.0

-26.0 EW1
NESZ [dB]

EW2
-28.0
EW3
EW4
-30.0
EW5

-32.0

-34.0

-36.0
18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
Incidence Angles [deg]

Figure B-37 NESZ Performance of the EW_SLC Product at Minimum Altitude

NESZ Performance of the EW_SLC product at Maximum Altitude

-22.0

-24.0

-26.0 EW1
NESZ [dB]

EW2
-28.0
EW3
EW4
-30.0
EW5

-32.0

-34.0

-36.0
18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Incidence Angles [deg]

Figure B-38 NESZ Performance of the EW_SLC Product at Maximum Altitude

ESA Unclassified – For Official Use

B-20
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

B4 WV Mode

This section provides the following graphs:

• Variation of the WV near and far range incidence angles along the orbit
• Ground range resolution of the WV_SLC and WV_GRD_MR products, at
minimum and maximum orbit altitude
• Range DTAR performance of the WV_SLC product, at minimum and
maximum orbit altitude
• NESZ performance of the WV_SLC product, at minimum and maximum orbit
altitude

Near Range Incidence along Orbit for WV beams

40.00
Incidence angle [deg]

35.00

30.00 WV1 near

25.00 WV2 near

20.00

15.00
-90.00 -40.00 10.00 60.00
Latitude [deg]

Figure B-39 Variation of the Near Range Incidence Angle along the Orbit for WV Mode

Far Range Incidence along Orbit for WV beams

40.00
Incidence angle [deg]

35.00

30.00 WV1 far

25.00 WV2 far

20.00

15.00
-90.00 -40.00 10.00 60.00
Latitude [deg]

Figure B-40 Variation of the Far Range Incidence Angle along the Orbit for WV Mode

ESA Unclassified – For Official Use

B-21
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Ground Range Resolution of the WV_SLC Product at Minimum Altitude

5.3
5.2
Ground Range Resolution [m]

5.2
5.1
5.1
5.0 WV1
5.0 WV2
4.9
4.9
4.8
4.8
4.7
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Incidence Angles [deg]

Figure B-41 Ground Range Resolution of the WV_SLC Product at Minimum Altitude

Ground Range Resolution of the WV_SLC Product at Maximum Altitude

5.5

5.5
Ground Range Resolution [m]

5.4

5.4

5.3 WV1
5.3 WV2

5.2

5.2

5.1

5.1
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Incidence Angles [deg]

Figure B-42 Ground Range Resolution of the WV_SLC Product at Maximum Altitude

ESA Unclassified – For Official Use

B-22
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Ground Range Resolution of the WV_GRD_MR Product at Minimum Altitude

52.5
52.0
51.5
Slant Range Resolution [m]

51.0
50.5
50.0 WV1
49.5 WV2
49.0
48.5
48.0
47.5
47.0
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Incidence Angles [deg]

Figure B-43 Ground Range Resolution of the WV_GRD_MR Product at Minimum

Altitude

Ground Range Resolution of the WV_GRD_MR Product at Maximum Altitude

55.0

54.5
Slant Range Resolution [m]

54.0

53.5

53.0 WV1
52.5 WV2

52.0

51.5

51.0

50.5
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Incidence Angles [deg]

Figure B-44 Ground Range Resolution of the WV_GRD_MR Product at Maximum

Altitude

ESA Unclassified – For Official Use

B-23
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

Range DTAR Performance of the WV_SLC Product at Minimum Altitude

-25

-30
RANGE DTAR [dB]

WV VV
-35
WV VH

-40 WV2 VV

WV2 VH
-45

-50
19 21 23 25 27 29 31 33
Off-Nadir Angles [deg]

Figure B-45 Range DTAR Performance of the WV_SLC Product at Minimum Altitude

Range DTAR Performance of the WV_SLC Product at Maximum Altitude

-25
RANGE DTAR [dB]

-30
WV VV
-35
WV VH
-40 WV2 VV
s WV2 VH
-45
-50
-55
19 21 23 25 27 29 31 33
Off-Nadir Angles [deg]

Figure B-46 Range DTAR Performance of the WV_SLC Product at Maximum Altitude

ESA Unclassified – For Official Use

B-24
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

NESZ Performance of the WV_SLC product at Minimum Altitude

-23.0

-24.0

-25.0
NESZ [dB]

-26.0
WV1
WV2
-27.0

-28.0

-29.0

-30.0
18 20 22 24 26 28 30 32 34 36 38 40
Incidence Angles [deg]

Figure B-47 NESZ Performance of the WV_SLC Product at Minimum Altitude

NESZ Performance of the WV_SLC product at Maximum Altitude

-23.0

-24.0

-25.0
NESZ [dB]

-26.0
WV1
WV2
-27.0

-28.0

-29.0

-30.0
18 20 22 24 26 28 30 32 34 36 38 40
Incidence Angles [deg]

Figure B-48 NESZ Performance of the WV_SLC Product at Maximum Altitude

ESA Unclassified – For Official Use

B-25
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

C DETAILED DERIVATION OF LEVEL 1 PRODUCT

CHARACTERISTICS

The detailed derivation of the Level 1 product characteristics is provided in the

Excel file S1-RS-MDA-52-7440_ProductDefinition_v2_4_AppendixC.xls.

ESA Unclassified – For Official Use

C-1
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

D PRODUCT DEFINITION RELATED ISSUES

This appendix contains discussions relative to the derivation of the predicted ENL
and the Doppler Centroid Frequency Estimation.

D1 Natural Looks, Processing Looks and ENL

The number of natural azimuth looks is one for all modes. For each GRD product,
the number of processing looks and the overlap values were set in such a way as to
achieve an approximately constant geometrical (range or azimuth) resolution
between swaths and close to equal resolutions in the azimuth and range directions.

The ENL of the GRD products was estimated based on a one-dimensional

simulation of 128 K samples of Gaussian complex noise weighted with the
Hamming window corresponding to each mode and beam. The ENL is a function of
the number of processing looks and the degree of correlation between them; when
there is no overlapping, ENL is equivalent to the number of processing looks. The
look correlation is affected by both the amount of overlapping between looks and
the weighting applied to the looks. When weighting is used, the ENL is larger for a
given overlap, because the overlapping portions of the looks are de-emphasized.

Figure D-1 presents this dependency for the 2 processing looks and the 3 distinct
(azimuth) Hamming windows applied in the Sentinel-1 Stripmap case. From the
figure, one can see that, if desired, one way to achieve constant ENL across swaths
would be to use the same amount of overlap and the same amount of weighting
(clearly the change in weighting would slightly affect the geometric resolution).

ESA Unclassified – For Official Use

D-1
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

o
Effect of Hamming Window on ENL, SM mode
o
l

f
o 1.95

r
e
b 1.9
m
u
n
1.85
t
n
e
l 1.8
a
v
i 1.75
u
q SM1 w inCoef = 0.7
E SM2 w inCoef = 0.75
1.7 SM3 w inCoef = 0.52

0 5 10 15 20 25 30 35 40 45 50
Percentage look overlap

Figure D-1 Equivalent Number of Looks

For the TOPSAR modes, the azimuth multi-looking may be performed by a time-
domain averaging (rather than by a (spectrum) look-summation). In this case the
(averaged) data will have a different statistical distribution and therefore the ENL
definition (as described in A1.2) no longer applies.

D2 Doppler Centroid Frequency Accuracy

Estimation of the Doppler centroid frequency, or simply Doppler centroid (DC), is

an essential part of SAR processing. Poor estimates can affect radiometry,
registration and focusing and raise the noise and ambiguity levels in the processed
image (see [R-5]). For the TOPSAR modes in particular, due to the bursty nature of
the (ScanSAR) data, periodic azimuth modulation of image amplitude (known as
scalloping) can be caused by even relatively small DC errors.

The radiometric error due to a DC frequency error can be reduced by the process of
multi-looking, which means that the products that are most sensitive (from the
radiometric point of view) to DC frequency errors are SLC products.

ESA Unclassified – For Official Use

D-2
 Ref: S1-RS-MDA-52-7440
MPC Nom: DI-MPC-PB
Sentinel-1 MPC Ref:
Issue/Revision:
MPC-0239
2/7
Date: 25/03/2016

The accuracy of the DC frequency estimation is relatively difficult to assess.

Typically, this characteristic is assessed using indirect methods such as:
a) Analyzing the consistency and trends of the DC frequency estimations from
data with the values calculated from geometry, over the same scenes. (This is
made possible by the high measurement and beam pointing accuracy of
Sentinel-1).
b) Analyzing the effect of intentionally introduced DC frequency errors on image
characteristics like radiometry and ambiguity ratios.

The quality of the DC frequency estimation performed in either the RADARSAT-

1/2 or the ENVISAT/ASAR MDA processors is considered very good with respect
to the requirements of those systems. To address the more stringent Sentinel-1 DC
accuracy requirements, the Sentinel-1 DC estimation scheme includes a refinement
of the existing algorithms consisting of a filtering of un-reliable estimates based on
scene-content (to supplement the already existing filtering based on statistical
criteria).

ESA Unclassified – For Official Use

D-3