Package ‘Evapotranspiration’

October 12, 2022

Version 1.16
Date 2022-01-10
Title Modelling Actual, Potential and Reference Crop
Evapotranspiration
Author Danlu Guo [aut, cre] <danlu.guo@adelaide.edu.au>, Seth Wes-
tra [aut] <swestra@civeng.adelaide.edu.au>, Tim Peter-
son [ctb] <tim.peterson@monash.edu>
Maintainer Danlu Guo <danlu.guo@unimelb.edu.au>
Depends R (>= 3.5.0), zoo
Description Uses data and constants to calculate potential evapotranspiration (PET) and actual evapo-
transpiration (AET) from 21 different formulations including Penman, Penman-
Monteith FAO 56, Priestley-Taylor and Morton formulations.
License GPL (>= 2)
NeedsCompilation no
Repository CRAN
Date/Publication 2022-01-10 05:22:41 UTC

R topics documented:
climatedata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
defaultconstants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
ET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
ET.Abtew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
ET.BlaneyCriddle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
ET.BrutsaertStrickler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
ET.ChapmanAustralian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
ET.GrangerGray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
ET.Hamon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
ET.HargreavesSamani . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
ET.JensenHaise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
ET.Linacre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

1
2 climatedata

ET.Makkink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
ET.MattShuttleworth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
ET.McGuinnessBordne . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
ET.MortonCRAE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
ET.MortonCRWE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
ET.Penman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
ET.PenmanMonteith . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
ET.PenPan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
ET.PriestleyTaylor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
ET.Romanenko . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
ET.SzilagyiJozsa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
ET.Turc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
ETComparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
ETForcings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
ETPlot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
E_OBS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
processeddata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
ReadInputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
ReadOBSEvaporations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Index 74

climatedata Raw Climate Data Required for Calculating Evapotranspiration

Description
This data set contains the raw climate data including the variables required for calculating evap-
otranspiration in function ET over the observation period between 1/3/2001 and 08/31/2004 at the
Kent Town station in Adelaide, Australia.

Usage
data(climatedata)

Format
A data frame containing 10240 obserations of 9 objects:

Station.Number - weather station number,

Year - year of record,
Month - month of record,
Day - day of record,
Hour - hour of record,
Tdew - subdaily dew point temperature in degree Celcius,
RH - subdaily relative humidity in percentage,
Rs - subdaily solar radiation in Megajoule per square meter,
uz - subdaily wind speed in meter per second.
constants 3

Source
Bureau of Meteorology, Kent Town, Adelaide, Australia

constants Constants Required for Calculating Evapotranspriation

Description
This data set contains the universal constants, and examples of other variable constants required for
calculating evapotranspiration in function ET, based on the climatic condition at Kent Town station
in Adelaide, Australia.

Usage
data(constants)

Format
A list containing 36 constant values including:

- 20 universal constants, which should be kept unchanged for most conditions:

lambda latent heat of evaporisationin = 2.45 MJ.kg^-1 at 20 degree Celcius,

sigma Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1,
Gsc solar constant = 0.0820 MJ.m^-2.min^-1
Roua mean density of air = 1.2 kg.m^-3 at 20 degree Celcius
Ca specific heat of air = 0.001013 MJ.kg^-1.K^-1
G soil heat flux negligible for daily time-step = 0 (Allen et al., 1998, page 68)
alphaA Albedo for Class-A pan = 0.14

alphaPT Priestley-Taylor coefficient:

= 1.26 for Priestley-Taylor formula (Priestley and Taylor, 1972, Sect. 6; Eichinger et al., 1996,
p.163);
= 1.31 for Szilagyi-Jozsa formula (Szilagyi and Jozsa, 2008);
= 1.28 for Brutsaert-Strickler formula (Brutsaert and Strickler, 1979),

ap constant in Penpan formula = 2.4,

b0 constant in Morton’s procedure = 1 (Chiew and McMahon, 1991, Table A1),
b1 constant in Morton’s procedure = 14 W.m^-2 (Chiew and McMahon, 1991, Table A1),
*Note: a re-calibrated value of 13.4 W.m^-2 was recommended to achieve achieve a Priestley-
Taylor coefficient of 1.26 (Wang et al., 2009), rather the original value (14 W.m^-2) used by Morton
that gave a Priestley-Taylor coefficient of 1.32;

b2 constant in Morton’s procedure = 1.2 (Chiew and McMahon, 1991, Table A1),
*Note: a re-calibrated value of 1.13 was recommended to achieve achieve a Priestley-Taylor co-
efficient of 1.26 (Wang et al., 2009), rather the original value (1.2) used by Morton that gave a
4 constants

Priestley-Taylor coefficient of 1.32;

e0 constant for Blaney-Criddle formula = 0.81917 (Frevert et al., 1983, Table 1),
e1 constant for Blaney-Criddle formula = -0.0040922 (Frevert et al., 1983, Table 1),
e2 constant for Blaney-Criddle formula = 1.0705 (Frevert et al., 1983, Table 1),
e3 constant for Blaney-Criddle formula = 0.065649 (Frevert et al., 1983, Table 1),
e4 constant for Blaney-Criddle formula = -0.0059864 (Frevert et al., 1983, Table 1),
e5 constant for Blaney-Criddle formula = -0.0005967 (Frevert et al., 1983, Table 1),
epsilonMo Land surface emissivity in Morton’s procedure = 0.92,
sigmaMo Stefan-Boltzmann constant in Morton’s procedure = 5.67e-08 W.m^-2.K^-4.

- 16 variable constants, which are specific for the climatic condition at Kent Town station in Ade-
laide, Australia:

lat latitude = -34.9211 degrees for Kent Town station,

lat_rad latitude in radians = -0.6095 radians for Kent Town station,
as fraction of extraterrestrial radiation reaching earth on sunless days = 0.23 for Australia (Roder-
ick, 1999, page 181),
bs difference between fracion of extraterrestrial radiation reaching full-sun days and that on sunless
days = 0.5 for Australia (Roderick, 1999, page 181),
Elev ground elevation above mean sea level = 48m for Kent Town station,
z height of wind instrument = 10m for Kent Town station,

fz constant in Morton’s procedure:

= 28.0 W.m^-2.mbar^-1 for CRAE model for T >= 0 degree Celcius;
*Note: a re-calibrated value of 29.2 W.m^-2.mbar^-1 was recommended to achieve achieve a
Priestley-Taylor coefficient of 1.26 (Wang et al., 2009), rather the original value (28.0 W.m^-
2.mbar^-1) used by Morton that gave a Priestley-Taylor coefficient of 1.32;

= 28.0*1.15 W.m^-2.mbar^-1 for CRAE model for T < 0 degree Celcius;

= 25.0 W.m^-2.mbar^-1 for CRWE model for T >= 0 degree Celcius;

= 28.75 W.m^-2.mbar^-1 for CRWE model for T < 0 degree Celcius (Morton, 1983a, page65).

a_0 constant for estimating sunshine hours from cloud cover data = 11.9 for Adelaide (Chiew and
McMahon, 1991, Table A1),
b_0 constant for estimating sunshine hours from cloud cover data = -0.15 for Adelaide,
c_0 constant for estimating sunshine hours from cloud cover data = -0.25 for Adelaide,
d_0 constant for estimating sunshine hours from cloud cover data = -0.0107 for Adelaide, gammaps
product of Psychrometric constant and atmospheric pressure as sea level:
= 0.66 mbar. degree Celcius^-1 for CRAE model for T >= 0 degree Celcius;
= 0.66/1.15 mbar. degree Celcius^-1 for CRAE model for T < 0 degree Celcius.
PA annual precipitation = 285.8mm for Kent Town station,

alphaMo constant in Morton’s procedure:

= 17.27 when T >= 0 degree Celcius;
= 21.88 when T < 0 degree Celcius.
defaultconstants 5

betaMo constant in Morton’s procedure:

= 237.3 degree Celcius when T >= 0 degree Celcius;
= 265.5 degree Celcius when T < 0 degree Celcius.

lambdaMo latent heat of vaporisation in Morton’s procedure:

= 28.5W.day.kg^-1 when T >= 0 degree Celcius;
= 28.5*1.15W.day.kg^-1 when T < 0 degree Celcius.

References
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Allen, R. G., Pereira, L. S., Raes, D. & Smith, M. 1998. Crop evapotranspiration-Guidelines for
computing crop water requirements-FAO Irrigation and drainage. paper 56. FAO, Rome, 300,
6541.
Szilagyi, J., & Jozsa, J. 2008. New findings about the complementary relationship-based evapora-
tion estimation methods. Journal of Hydrology, 354(1-4), 171-186.
Brutsaert, W., & Stricker, H. 1979. An advection-aridity approach to estimate actual regional evap-
otranspiration. Water Resources Research, 15(2), 443-450.
Chiew, F. H. S., & McMahon, T. A. 1991. The applicability of Morton’s and Penman’s evapotran-
spiration estimates in rainfall-runoff modelling. JAWRA Journal of the American Water Resources
Association, 27(4), 611-620.
Frevert, D.K., Hill, R.W.Braaten, B.C. 1983, Estimation of FAO evapotranspiration coefficients,
Journal of Irrigation and Drainage Engineering, vol. 109, no. 2, pp. 265-270.
Roderick, M. L. 1999. Estimating the diffuse component from daily and monthly measurements of
global radiation. Agricultural and Forest Meteorology, 95(3), 169-185.
Wang, Q. J., McConachy, F. L. N., Chiew, F. H. S., James, R., de Hoedt, G. C., & Wright, W. J. 2009.
Maps of Evapotranspiration. Retrieved from Melbourne, Australia: http://www.bom.gov.au/climate/averages/climatology/eva
description.pdf
Morton, F. I. 1983. Operational estimates of areal evapotranspiration and their significance to the
science and practice of hydrology. Journal of Hydrology, 66(1-4), 1-76. doi:http://dx.doi.org/10.1016/0022-
1694(83)90177-4

See Also
defaultconstants

defaultconstants Universal constants Required for Calculating Evapotranspriation

Description
This data set contains the universal constants required for calculating evapotranspiration in function
ET, which should be kept unchanged for most conditions. Please note that additional constants may
be ET models - check the manual for individual ET models for details.
6 ET

Usage

data(defaultconstants)

Format

A list containing 20 constant values including:

lambda latent heat of evaporisationin = 2.45 MJ.kg^-1 at 20 degree Celcius,
sigma Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1,
Gsc solar constant = 0.0820 MJ.m^-2.min^-1
Roua mean density of air = 1.2 kg.m^-3 at 20 degree Celcius
Ca specific heat of air = 0.001013 MJ.kg^-1.K^-1
G soil heat flux negligible for daily time-step = 0 (Allen et al., 1998, page 68)
alphaA Albedo for Class-A pan = 0.14

alphaPT Priestley-Taylor coefficient:

= 1.26 for Priestley-Taylor formula (Priestley and Taylor, 1972, Sect. 6; Eichinger et al., 1996,
p.163);
= 1.31 for Szilagyi-Jozsa formula (Szilagyi and Jozsa, 2008);
= 1.28 for Brutsaert-Strickler formula (Brutsaert and Strickler, 1979),

ap constant in Penpan formula = 2.4,

b0 constant in Morton’s procedure = 1 (Chiew and McMahon, 1991, Table A1),
b1 constant in Morton’s procedure = 14 W.m^-2 (Chiew and McMahon, 1991, Table A1),
b2 constant in Morton’s procedure = 1.2 (Chiew and McMahon, 1991, Table A1),
e0 constant for Blaney-Criddle formula = 0.81917 (Frevert et al., 1983, Table 1),
e1 constant for Blaney-Criddle formula = -0.0040922 (Frevert et al., 1983, Table 1),
e2 constant for Blaney-Criddle formula = 1.0705 (Frevert et al., 1983, Table 1),
e3 constant for Blaney-Criddle formula = 0.065649 (Frevert et al., 1983, Table 1),
e4 constant for Blaney-Criddle formula = -0.0059864 (Frevert et al., 1983, Table 1),
e5 constant for Blaney-Criddle formula = -0.0005967 (Frevert et al., 1983, Table 1),
epsilonMo Land surface emissivity in Morton’s procedure = 0.92,
sigmaMo Stefan-Boltzmann constant in Morton’s procedure = 5.67e-08 W.m^-2.K^-4.

Source

various references

See Also

constants

ET ET Formulations
ET 7

Description
A generic function including 17 different specific methods that are all named following the format
of ET.methodname. Once specific function is called the corresponding calculations are performed
and a calculation summary is printed to screen.

Usage
ET(data, constants, ...)

Arguments
data A list of climate data required for estimating evapotranspiration which differs
for each evapotranspiration formulations, see specific formulations for details.
constants A list named constants consists of constants required for the ET models which
mdiffer for specific ET models - refer to the manual for individual models for
details.
... Arguments to be passed to methods which differs for each evapotranspiration
formulations, see specific formulations for details.

Details
Individual ET methods can be called by substituting the ’methodname’ by the function name (e.g.
ET.Penman to call the Penman model).

When the ET model selection is not specified by users, this function determines the default model
to use based on the availability of climate data presented. Wherever data are available, the more
comprehensive, physically-based models are always preferred over the empirical models, in the fol-
lowing hierarchy:

- If all variables of Tmax/Tmin and RHmax/RHmin and either uz or u2, and either Rs of n or Cd
are available, and short crop surface is specified in argument:
Penman-Monteith FAO56 (ET.PenmanMonteith with crop = "short");

- If all variables of Tmax/Tmin and RHmax/RHmin and either uz or u2, and either Rs of n or Cd
are available, and long crop surface is specified in argument:
Penman-Monteith ASCE-EWRI (ET.PenmanMonteith with crop = "long");

- If all variables of Tmax/Tmin and RHmax/RHmin and either uz or u2, and either Rs of n or Cd
are available, and no surface is specified:
Penman (ET.Penman);

- If all variables of Tmax/Tmin and RHmax/RHmin, and either Rs of n or Cd are available:

Priestley-Taylor (ET.PriestleyTaylor);

- If all variables of Tmax/Tmin and either Rs of n or Cd are available:

Makkink (ET.Makkink);
8 ET.Abtew

- If all variables of Tmax/Tmin are available:

Hargreaves-Samani (ET.HargreavesSamani).

Author(s)
Danlu Guo

Examples
# Use processed existing data set from kent Town, Adelaide
data("processeddata")
data("constants")

# Call generic function ET() - leads to the use of Penman model

results_default <- ET(processeddata, constants, save.csv="no")

# Call generic function ET() - leads to the use of Penman-Monteith model

results_crop <- ET(processeddata, constants, crop = "short", save.csv="no")

ET.Abtew Abtew Formulation

Description
Implementing the Abtew formulation for estimating actual evapotranspiration.

Usage
## S3 method for class 'Abtew'
ET(data, constants, ts="daily", solar="sunshine hours",
message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data in class "Abtew" which contains the following items (climate vari-
ables) required by Abtew formulation:
Tmax, Tmin (degree Celcius), Rs (Megajoules per sqm) or n (hour) or Cd (okta)
constants A list named constants consists of constants required for the calculation of
Abtew formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1.

The following constants are also required when argument solar has value of
sunshine hours:
as - fraction of extraterrestrial radiation reaching earth on sunless days,
ET.Abtew 9

bs - difference between fracion of extraterrestrial radiation reaching full-sun

days and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Option for calculating solar radiation (i.e. the value of argument solar)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The alternative calculation options can be selected through argument solar, please see Arguments
for details.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Abtew actual evapotranspiration.

ET.Monthly Monthly aggregated estimations of Abtew actual evapotranspiration.
ET.Annual Annually aggregated estimations of Abtew actual evapotranspiration.
ET.MonthlyAve Monthly averaged estimations of daily Abtew actual evapotranspiration.
ET.AnnualAve Annually averaged estimations of daily Abtew actual evapotranspiration.
ET_formulation Name of the formulation used which equals to Abtew.
ET_type Type of the estimation obtained which is Actual Evapotranspiration.
10 ET.BlaneyCriddle

message1 A message to inform the users about how solar radiation has been calculated by
using which data.

Author(s)
Danlu Guo

References
Abtew, W. 1996. Evapotranspiration measurements and modeling for three wetland systems in
south florida. Wiley Online Library.

See Also
ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.Abtew under the generic function ET

results <- ET.Abtew(processeddata, constants,ts="daily", solar="sunshine hours",
message="yes", AdditionalStats="yes", save.csv="no")

ET.BlaneyCriddle Blaney-Criddle Formulation

Description
Implementing the Blaney-Criddle formulation for estimating reference crop evapotranspiration.

Usage
## S3 method for class 'BlaneyCriddle'
ET(data, constants, ts="daily", solar="sunshine hours", height = F,
message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Blaney-Criddle formulation:
Tmax, Tmin (degree Celcius), RHmin (per cent), n (hour) or Cd (okta), u2 or uz
(meter per second)
ET.BlaneyCriddle 11

constants A list named constants consists of constants required for the calculation of
PenPan formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
z - height of wind instrument in m,
e0,e1,e2,e3,e4 - recommended values of 0.81917, -0.0040922, 1.0705, 0.065649,
-0.0059684, -0.0005967 respectively (Table 1 in Frevert et al., 1983).
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either sunshine hours or cloud:
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data.
Default is sunshine hours.
height Must be T or F, indicating if adjustment for site elevation for arid and semi-arid
regions is applied in Blaney-Criddle formulation (Allen and Brockway, 1983).
Default is F for no adjustment.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Evaporative surface
- Option for calculating solar radiation (i.e. the value of argument solar)
- If height adjustment has been applied on results (i.e. the value of argument
height)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details

The alternative calculation options can be selected through argument solar, please see Arguments
for details.
Height adjustment for the estimations is available through argument height, please see Arguments
for details.
12 ET.BlaneyCriddle

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Blaney-Criddle reference crop evapotranspira-

tion.
ET.Monthly Monthly aggregated estimations of Blaney-Criddle reference crop evapotranspi-
ration.
ET.Annual Annually ggregated estimations of Blaney-Criddle reference crop evapotranspi-
ration.
ET.MonthlyAve Monthly averaged estimations of daily Blaney-Criddle reference crop evapo-
transpiration.
ET.AnnualAve Annually averaged estimations of daily Blaney-Criddle reference crop evapo-
transpiration.
ET_formulation Name of the formulation used which equals to Blaney-Criddle.
ET_type Type of the estimation obtained which is Reference Crop Evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.
message3 A message to inform the users about if height adjustment has been applied to
calculated Blaney-Criddle reference crop evapotranspiration.

Author(s)
Danlu Guo

References
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Allen, R.G.Brockway, C.E. 1983, Estimating consumptive use on a statewide basis. Advances in
Irrigation and Drainage@ sSurviving External Pressures, ASCE, pp. 79-89.
Allen, R. & Pruitt, W. 1986. Rational Use of The FAO Blaney-Criddle Formula. Journal of Irrigation
and Drainage Engineering, 112, 139-155.
Frevert, D.K., Hill, R.W.Braaten, B.C. 1983, Estimation of FAO evapotranspiration coefficients,
Journal of Irrigation and Drainage Engineering, vol. 109, no. 2, pp. 265-270.

See Also
ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")
ET.BrutsaertStrickler 13

# Call ET.BlaneyCriddle under the generic function ET

results <- ET.BlaneyCriddle(processeddata, constants, ts="daily", solar="sunshine hours",
height= FALSE, message="yes", AdditionalStats="yes", save.csv="no")

ET.BrutsaertStrickler Brutsaert-Strickler Formulation

Description
Implementing the Brutsaert-Strickler formulation for actual areal evapotranspiration

Usage
## S3 method for class 'BrutsaertStrickler'
ET(data, constants, ts="daily", solar="sunshine hours", alpha=0.23,
message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Brutsaert-Strickler formulation:
Tmax, Tmin (degree Celcius), RHmax, RHmin (per cent), Rs (Megajoules per
sqm) or n (hour) or Cd (okta), u2 or uz (meter per second)
constants A list named constants consists of constants required for the calculation of
Brutsaert-Strickler formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
z - height of wind instrument in m,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1.

The following constants are also required when argument solar has value of
sunshine hours:
as - fraction of extraterrestrial radiation reaching earth on sunless days,
bs - difference between fracion of extraterrestrial radiation reaching full-sun
days and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
14 ET.BrutsaertStrickler

monthly precipitation indicates that solar radiation is to be calculated di-

rectly from monthly precipitation.
Default is sunshine hours.
alpha Any numeric value between 0 and 1 (dimensionless), albedo of the evaporative
surface representing the portion of the incident radiation that is reflected back at
the surface.
Default is 0.23 for surface covered with short reference crop.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Evaporative surface with values of albedo, surface resistance, crop height and
roughness height
- Option for calculating solar radiation (i.e. the value of argument solar)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The alternative calculation options can be selected through argument solar, please see Arguments
for details.
User-defined evaporative surface is allowed through argument alpha, please see Arguments for
details.

Value
The function also generates a list containing the following components:

ET.Daily Daily aggregated estimations of Brutsaert-Strickler actual areal evapotranspira-

tion.
ET.Monthly Monthly aggregated estimations of Brutsaert-Strickler actual areal evapotranspi-
ration.
ET.Annual Annually aggregated estimations of Brutsaert-Strickler actual areal evapotran-
spiration.
ET.MonthlyAve Monthly averaged estimations of daily Brutsaert-Strickler actual areal evapo-
transpiration.
ET.AnnualAve Annually averaged estimations of daily Brutsaert-Strickler actual areal evapo-
transpiration.
ET.ChapmanAustralian 15

ET_formulation Name of the formulation used which equals to Brutsaert-Strickler.

ET_type Type of the estimation obtained which is Actual Areal Evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.

Author(s)

Danlu Guo

References

McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.

See Also

ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.BrutsaertStrickler under the generic function ET

results <- ET.BrutsaertStrickler(processeddata, constants, ts="daily", solar="sunshine hours",
alpha=0.23, message="yes", AdditionalStats="yes", save.csv="no")

ET.ChapmanAustralian Chapman Formulation

Description

Implementing the Chapman formulation for estimating potential evapotranspiration.

Usage

## S3 method for class 'ChapmanAustralian'

ET(data, constants, ts="daily", PenPan= T,
solar="sunshine hours", alpha=0.23, message="yes", AdditionalStats="yes",
save.csv="no", ...)
16 ET.ChapmanAustralian

Arguments
data A list of data which contains the following items (climate variables) required by
Chapman formulation:
Tmax, Tmin (degree Celcius), RHmax, RHmin (per cent), Rs (Megajoules per
sqm) or n (hour) or Cd (okta), u2 or uz (meter per second)
constants A list named constants consists of constants required for the calculation of
Chapman formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
z - height of wind instrument in m,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1,
lat - latitude in degrees,
alphaA - albedo for Class-A pan,
ap - a constant in PenPan = 2.4.

The following constants are also required when argument solar has value of
sunshine hours:
as - fraction of extraterrestrial radiation reaching earth on sunless days,
bs - difference between fracion of extraterrestrial radiation reaching full-sun
days and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
PenPan Must be T or F, indicating if the PenPan formulation is used for estimating Class-
A pan evaporation required in Chapman formulation. If T PenPan will be used
and if F the actual data of Class-A pan evaporation will be used. Default is T for
using the PenPan formulation.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
alpha Any numeric value between 0 and 1 (dimensionless), albedo of the evaporative
surface incident radiation that is reflected back at the surface.
Default is 0.23 for surface covered with short reference crop.
message Must be either yes or no, indicating whether message should be printed for cal-
culation summary including the following elements:
- ET model name and ET quantity estimated, and the value of pan coefficient
(only for when potential ET is estimated)
- Evaporative surface with values of albedo
- Option for calculating solar radiation (i.e. the value of argument solar)
ET.ChapmanAustralian 17

- If the PenPan formulation is used for estimating Class-A pan evaporation re-
quired in Chapman formulation (i.e. the value of argument PenPan)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The alternative calculation options can be selected through arguments PenPan and solar, please
see Arguments for details.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Chapman potential evapotranspiration.

ET.Monthly Monthly aggregated estimations of Chapman potential evapotranspiration.
ET.Annual Annually aggregated estimations of Chapman equivalent Penmen-Monteith evap-
otranspiration.
ET.MonthlyAve Monthly averaged estimations of daily Chapman potential evapotranspiration.
ET.AnnualAve Annually averaged estimations of daily Chapman potential evapotranspiration.
ET_formulation Name of the formulation used which equals to Chapman.
ET_type Type of the estimation obtained which is Potential Evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.
message5 A message to inform the users about if the Class-A pan evaporation is from
actual data or from PenPan estimation.

Author(s)
Danlu Guo

References
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
18 ET.GrangerGray

Chapman, T. 2001, Estimation of evaporation in rainfall-runoff models, in F. Ghassemi, D. Post, M.

SivapalanR. Vertessy (eds), MODSIM2001: Integrating models for Natural Resources Management
across Disciplines, Issues and Scales, MSSANZ, vol. 1, pp. 293-298.

See Also
ET,processeddata,defaultconstants,constants,ET.PenPan

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.ChapmanAustralian under the generic function ET

results <- ET.ChapmanAustralian(processeddata, constants, ts="daily", PenPan= TRUE,
solar="sunshine hours", alpha=0.23, message="yes", AdditionalStats="yes",
save.csv="no")

ET.GrangerGray Granger-Gray Formulation

Description
Implementing the Granger-Gray formulation for estimating actual areal evapotranspiration.

Usage
## S3 method for class 'GrangerGray'
ET(data, constants, ts="daily",
solar="sunshine hours", windfunction_ver=1948, alpha=0.23,
message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Granger-Gray formulation:
Tmax, Tmin (degree Celcius), RHmax, RHmin (per cent), Rs (Megajoules per
sqm) or n (hour) or Cd (okta), u2 or uz (meter per second)
constants A list named constants consists of constants required for the calculation of
Granger-Gray formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
z - height of wind instrument in m,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1.
G - soil heat flux in MJ.m^-2.day^-1, = 0 when using daily time step.
ET.GrangerGray 19

The following constants are also required when argument solar has value of
sunshine hours:
as - fraction of extraterrestrial radiation reaching earth on sunless days,
bs - difference between fracion of extraterrestrial radiation reaching full-sun
days and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
windfunction_ver
The version of Penman wind function that will be used within the Penman for-
mulation. Must be either 1948 or 1956.
1948 is for applying the Penman’s 1948 wind function (Penman, 1948);
1956 is for applying the Penman’s 1956 wind function (Penman, 1956) Default
is 1948.
alpha Any numeric value between 0 and 1 (dimensionless), albedo of evaporative sur-
face representing the portion of the incident radiation that is reflected back at the
surface.
Default is 0.23 for surface covered with short reference crop.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Evaporative surface with values of albedo
- Option for calculating solar radiation (i.e. the value of argument solar)
- The version of Penman wind function has been used (i.e. the value of argument
windfunction_ver)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.
20 ET.GrangerGray

Details
The alternative calculation options can be selected through arguments solar and windfunction_ver,
please see Arguments for details.
User-defined evaporative surface is allowed through argument alpha, please see Arguments for de-
tails.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Granger-Gray actual areal evapotranspiration.

ET.Monthly Monthly aggregated estimations of Granger-Gray actual areal evapotranspira-
tion.
ET.Annual Annually aggregated estimations of Granger-Gray actual areal evapotranspira-
tion.
ET.MonthlyAve Monthly averaged estimations of daily Granger-Gray actual areal evapotranspi-
ration.
ET.AnnualAve Annually averaged estimations of daily Granger-Gray actual areal evapotranspi-
ration.
ET_formulation Name of the formulation used which equals to Granger-Gray.
ET_type Type of the estimation obtained which is Actual Areal Evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.
message2 A message to inform the users about which version of the Penman wind function
has been used.

Author(s)
Danlu Guo

References
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Penman, H. L. 1948. Natural evaporation from open water, bare soil and grass. Proceedings of the
Royal Society of London. Series A. Mathematical and Physical Sciences, 193, 120-145.
Penman, H. L. 1956. Evaporation: An introductory survey. Netherlands Journal of Agricultural
Science, 4, 9-29

See Also
ET,processeddata,defaultconstants,constants,ET.Penman
ET.Hamon 21

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.GrangerGray under the generic function ET

results <- ET.GrangerGray(processeddata, constants, ts="daily",
solar="sunshine hours", windfunction_ver=1948, alpha=0.23,
message="yes", AdditionalStats="yes", save.csv="no")

ET.Hamon Hamon Formulation

Description
Implementing the Hamon formulation for estimating potential evapotranspiration.

Usage
## S3 method for class 'Hamon'
ET(data, constants = NULL, ts="daily", message="yes", AdditionalStats="yes",
save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Hamon formulation:
Tmax, Tmin (degree Celcius), n (hour)
constants Dummy argument with a NULL value.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.
22 ET.Hamon

Details

This formulation provides a single calculation method with no alternatives available.

Value

The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Hamon potential evapotranspiration.

ET.Monthly Monthly aggregated estimations of Hamon potential evapotranspiration.
ET.Annual Annually aggregated estimations of Hamon potential evapotranspiration.
ET.MonthlyAve Monthly averaged estimations of daily Hamon potential evapotranspiration.
ET.AnnualAve Annually averaged estimations of daily Hamon potential evapotranspiration.
ET_formulation Name of the formulation used which equals to Hamon.
ET_type Type of the estimation obtained which is Potential Evapotranspiration.

Author(s)

Danlu Guo

References

Hamon, W. R. 1961. Estimating potential evapotranspiration. Journal of the Hydraulics Division,

87, 107-120.
Oudin, L., Hervieu, F., Michel, C., Perrin, C., Andreassian, V., Anctil, F.Loumagne, C. 2005,
Which potential evapotranspiration input for a lumped rainfall-runoff model?: Part 2-Towards a
simple and efficient potential evapotranspiration model for rainfall-runoff modelling. Journal of
Hydrology, vol. 303, no. 1-4, pp. 290-306.

See Also

ET,processeddata

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.Hamon under the generic function ET

results <- ET.Hamon(processeddata, ts="daily", message="yes", AdditionalStats="yes", save.csv="no")
ET.HargreavesSamani 23

ET.HargreavesSamani Hargreaves-Samani Formulation

Description
Implementing the Hargreaves-Samani formulation for estimating reference crop evapotranspiration.

Usage
## S3 method for class 'HargreavesSamani'
ET(data, constants, ts="daily",
message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Hargreaves-Samani formulation: Tmax, Tmin (degree Celcius)
constants A list named constants consists of constants required for the calculation of
Hargreaves-Samani formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1.

ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Evaporative surface with values of albedo
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
This formulation provides a single calculation method with no alternatives available.
24 ET.HargreavesSamani

Value

The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Hargreaves-Samani reference crop evapotran-

spiration.
ET.Monthly Monthly aggregated estimations of Hargreaves-Samani reference crop evapo-
transpiration.
ET.Annual Annually aggregated estimations of Hargreaves-Samani reference crop evapo-
transpiration.
ET.MonthlyAve Monthly averaged estimations of daily Hargreaves-Samani reference crop evap-
otranspiration.
ET.AnnualAve Annually averaged estimations of daily Hargreaves-Samani reference crop evap-
otranspiration.
ET_formulation Name of the formulation used which equals to Hargreaves-Samani.
ET_type Type of the estimation obtained which is Reference Crop Evapotranspiration.

Author(s)

Danlu Guo

References

McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Hargreaves, G.H.Samani, Z.A. 1985, Reference crop evapotranspiration from ambient air temper-
ature. American Society of Agricultural Engineers.

See Also

ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.HargreavesSamani under the generic function ET

results <- ET.HargreavesSamani(processeddata, constants, ts="daily", message="yes",
AdditionalStats="yes", save.csv="no")
ET.JensenHaise 25

ET.JensenHaise Jensen-Haise Formulation

Description
Implementing the Jensen-Haise formulation for estimating potential evapotranspiration.

Usage
## S3 method for class 'JensenHaise'
ET(data, constants, ts="daily", solar="sunshine hours",
message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required
by Jensen-Haise formulation: Tmax, Tmin, Rs or n or Cd Tmax, Tmin (degree
Celcius), Rs (Megajoules per sqm) or n (hour) or Cd (okta)
constants A list named constants consists of constants required for the calculation of
Jensen-Haise formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1.

The following constants are also required when argument solar has value of
sunshine hours:
as - fraction of extraterrestrial radiation reaching earth on sunless days,
bs - difference between fracion of extraterrestrial radiation reaching full-sun
days and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Option for calculating solar radiation (i.e. the value of argument solar)
26 ET.JensenHaise

- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
This formulation provides a single calculation method with no alternatives available.

Value
The function also generates a list containing the following components:

ET.Daily Daily aggregated estimations of Jensen-Haise potential evapotranspiration.

ET.Monthly Monthly aggregated estimations of Jensen-Haise potential evapotranspiration.
ET.Annual Annually aggregated estimations of Jensen-Haise potential evapotranspiration.
ET.MonthlyAve Monthly averaged estimations of daily Jensen-Haise potential evapotranspira-
tion.
ET.AnnualAve Annually averaged estimations of daily Jensen-Haise potential evapotranspira-
tion.
ET_formulation Name of the formulation used which equals to Jensen-Haise.
ET_type Type of the estimation obtained which is Potential Evapotranspiration.

Author(s)
Danlu Guo

References
Jensen, M.E.Haise, H.R. 1963, Estimating evapotranspiration from solar radiation. Proceedings of
the American Society of Civil Engineers, Journal of the Irrigation and Drainage Division, vol. 89,
pp. 15-41.
Prudhomme, C.Williamson, J. 2013, Derivation of RCM-driven potential evapotranspiration for
hydrological climate change impact analysis in Great Britain: a comparison of methods and asso-
ciated uncertainty in future projections. Hydrol. Earth Syst. Sci., vol. 17, no. 4, pp. 1365-1377.
Xu, C.Y.Singh, V.P. 2000, Evaluation and generalization of radiation-based methods for calculat-
ing evaporation., Hydrological Processes, vol. 14, no. 2, pp. 339-349.
ET.Linacre 27

See Also
ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.JensenHaise under the generic function ET

results <- ET.JensenHaise(processeddata, constants, ts="daily", solar="sunshine hours",
message="yes",AdditionalStats="yes", save.csv="no")

ET.Linacre Linacre Formulation

Description
Implementing the Linacre formulation for estimating actual evapotranspiration.

Usage
## S3 method for class 'Linacre'
ET(data, constants, ts="daily", message="yes", AdditionalStats="yes",
save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Linacre formulation:
Tmax, Tmin, Tdew (degree Celcius)
constants A list named constants consists of constants required for the calculation of
Linacre formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lat - latitude in degrees.

ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
28 ET.Linacre

AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
This formulation provides a single calculation method with no alternatives available.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Linacre actual evapotranspiration.

ET.Monthly Monthly aggregated estimations of Linacre actual evapotranspiration.
ET.Annual Annually aggregated estimations of Linacre actual evapotranspiration.
ET.MonthlyAve Monthly averaged estimations of daily Linacre actual evapotranspiration.
ET.AnnualAve Annually averaged estimations of daily Linacre actual evapotranspiration.
ET_formulation Name of the formulation used which equals to Linacre.
ET_type Type of the estimation obtained which is Actual Evapotranspiration.

Author(s)
Danlu Guo

References
Linacre, E. T. 1977. A simple formula for estimating evaporation rates in various climates, using
temperature data alone. Agricultural meteorology, 18, 409-424.

See Also
ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.Linacre under the generic function ET

results <- ET.Linacre(processeddata, constants, ts="daily",
message="yes", AdditionalStats="yes", save.csv="no")
ET.Makkink 29

ET.Makkink Makkink Formulation

Description
Implementing the Makkink formulation for estimating reference crop evapotranspiration.

Usage
## S3 method for class 'Makkink'
ET(data, constants, ts="daily", solar="sunshine hours",
message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Makkink formulation:
Tmax, Tmin (degree Celcius), Rs (Megajoules per sqm) or n (hour) or Cd (okta)
constants A list named constants consists of constants required for the calculation of
Makkink formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1.

The following constants are also required when argument solar has value of
sunshine hours:
as - fraction of extraterrestrial radiation reaching earth on sunless days,
bs - difference between fracion of extraterrestrial radiation reaching full-sun
days and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Option for calculating solar radiation (i.e. the value of argument solar)
- Time step of the output ET estimates (i.e. the value of argument ts)
30 ET.Makkink

- Units of the output ET estimates

- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The alternative calculation options can be selected through argument solar, please see Arguments
for details.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Makkink reference crop evapotranspiration.

ET.Monthly Monthly aggregated estimations of Makkink reference crop evapotranspiration.
ET.Annual Annually aggregated estimations of Makkink reference crop evapotranspiration.
ET.MonthlyAve Monthly averaged estimations of daily Makkink reference crop evapotranspira-
tion.
ET.AnnualAve Annually averaged estimations of daily Makkink reference crop evapotranspira-
tion.
ET_formulation Name of the formulation used which equals to Makkink.
ET_type Type of the estimation obtained which is Reference crop evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.

Author(s)
Danlu Guo

References
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
De Bruin, H. 1981, The determination of (reference crop) evapotranspiration from routine weather
data. Evaporation in relation to hydrology, pp. 25-37.
ET.MattShuttleworth 31

See Also
ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.Makkink under the generic function ET

results <- ET.Makkink(processeddata, constants, ts="daily", solar="sunshine hours",
message="yes", AdditionalStats="yes", save.csv="no")

ET.MattShuttleworth Matt-Shuttleworth Formulation

Description
Implementing the Matt-Shuttleworth formulation for reference crop evapotranspiration

Usage
## S3 method for class 'MattShuttleworth'
ET(data, constants, ts="daily", solar="sunshine hours",
alpha=0.23, r_s=70, CH=0.12, message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list which contains the following items (climate variables) required by Matt-
Shuttleworth formulation:
Tmax, Tmin (degree Celcius), RHmax, RHmin (per cent), Rs (Megajoules per
sqm) or n (hour) or Cd (okta), u2 or uz (meter per second)
constants A list named constants consists of constants required for the calculation of
Matt-Shuttleworth formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
z - height of wind instrument in m,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1,
Roua - mean air density = 1.20 kg.m^-3,
Ca - specific heat of air = 0.001013 MJ.kg^-1.oC^-1.

The following constants are also required when argument solar has value of
sunshine hours:
32 ET.MattShuttleworth

as - fraction of extraterrestrial radiation reaching earth on sunless days,

bs - difference between fracion of extraterrestrial radiation reaching full-sun
days and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
alpha Any numeric value between 0 and 1 (dimensionless), albedo of evaporative sur-
face representing the portion of the incident radiation that is reflected back at the
surface.
Default is 0.23 for surface covered with short reference crop, which is for the
calculation of Matt-Shuttleworth reference crop evaporation.
r_s Any value (seconds per metre), surface resistance depends on the type of refer-
ence crop.
Default is 70 for short reference crop.
CH Any value (metres), crop height depends on the reference crop.
Default is 0.12 for short reference crop.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Evaporative surface with values of albedo, surface resistance and crop height
- Option for calculating solar radiation (i.e. the value of argument solar)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The alternative calculation options can be selected through argument solar, please see Arguments
for details.
ET.MattShuttleworth 33

User-defined evaporative surface is allowed through arguments alpha, r_s and CH, please see
Arguments for details.

Value
The function generates a list containing the following components:
ET.Daily Daily aggregated estimations of Matt-Shuttleworth reference crop evapotranspi-
ration.
ET.Monthly Monthly aggregated estimations of Matt-Shuttleworth reference crop evapotran-
spiration.
ET.Annual Annually aggregated estimations of Matt-Shuttleworth reference crop evapo-
transpiration.
ET.MonthlyAve Monthly averaged estimations of daily Matt-Shuttleworth reference crop evapo-
transpiration.
ET.AnnualAve Annually averaged estimations of daily Matt-Shuttleworth reference crop evap-
otranspiration.
ET_formulation Name of the formulation used which equals to Matt-Shuttleworth.
ET_type Type of the estimation obtained which is Reference Crop Evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.

Author(s)
Danlu Guo

References
Shuttleworth, W. & Wallace, J. 2009. Calculating the water requirements of irrigated crops in
Australia using the Matt-Shuttleworth approach. Transactions of the ASABE, 52, 1895-1906.
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.

See Also
ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.MattShuttleworth under the generic function ET

results <- ET.MattShuttleworth(processeddata, constants, ts="daily",
solar="sunshine hours", alpha=0.23, r_s=70, CH=0.12,
message="yes", AdditionalStats="yes", save.csv="no")
34 ET.McGuinnessBordne

ET.McGuinnessBordne McGuinness-Bordne Formulation

Description
Implementing the McGuinness-Bordne formulation for estimating potential evapotranspiration.

Usage
## S3 method for class 'McGuinnessBordne'
ET(data, constants, ts="daily", message="yes",
AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
McGuinness-Bordne formulation: Tmax, Tmin (degree Celcius)
constants A list named constants consists of constants required for the calculation of
Jensen-Haise formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1.

ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
This formulation provides a single calculation method with no alternatives available.
ET.McGuinnessBordne 35

Value

The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of McGuinness-Bordne potential evapotranspira-

tion.
ET.Monthly Monthly aggregated estimations of McGuinness-Bordne potential evapotranspi-
ration.
ET.Annual Annually aggregated estimations of McGuinness-Bordne potential evapotran-
spiration.
ET.MonthlyAve Monthly averaged estimations of daily McGuinness-Bordne potential evapo-
transpiration.
ET.AnnualAve Annually averaged estimations of daily McGuinness-Bordne potential evapo-
transpiration.
ET_formulation Name of the formulation used which equals to McGuinness-Bordne.
ET_type Type of the estimation obtained which is Potential Evapotranspiration.

Author(s)

Danlu Guo

References

Oudin, L., Hervieu, F., Michel, C., Perrin, C., Andreassian, V., Anctil, F.Loumagne, C. 2005,
Which potential evapotranspiration input for a lumped rainfall-runoff model?: Part 2-Towards a
simple and efficient potential evapotranspiration model for rainfall-runoff modelling. Journal of
Hydrology, vol. 303, no. 1-4, pp. 290-306.
Xu, C.Y.Singh, V.P. 2000, Evaluation and generalization of radiation-based methods for calculat-
ing evaporation., Hydrological Processes, vol. 14, no. 2, pp. 339-349.

See Also

ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.McGuinnessBordne under the generic function ET

results <- ET.McGuinnessBordne(processeddata, constants, ts="daily",
message="yes", AdditionalStats="yes", save.csv="no")
36 ET.MortonCRAE

ET.MortonCRAE Morton CRAE Formulation

Description
Implementing the Morton CRAE formulation for estimating potential evapotranspiration, wet-environment
areal evapotranspiration and actual areal evapotranspiration.

Usage
## S3 method for class 'MortonCRAE'
ET(data, constants, ts="monthly", est="potential ET",
solar="sunshine hours", Tdew= T, alpha = NULL, message="yes", AdditionalStats="yes",
save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Morton CRAE formulation:
Tmax, Tmin, Tdew (degree Celcius) or va or RHmax and RHmin, Rs (Megajoules
per sqm) or n (hour) or Cd (okta)
constants A list named constants consists of constants required for the calculation of
Morton CRAE formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lat_rad - latitude in radians,
PA - annual precipitation in mm, required when precipitation data is not avail-
able,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1,
lat - latitude in degrees,
epsilonMo - surface emissivity = 0.92 (Morton, 1986),
fz - A constant in Morton’s procedure = 28.0 Wm^-2.mbar^-1 for T >= 0 degree
Celcius, and = 28.0*1.15 Wm^-2.mbar^-1 for T >= 0 degree Celcius for CRAE
model (Morton, 1983),
b0 - a constants in Morton’s procedure, = 1 for CRAE model (Morton, 1983),
b1 - a constant in Morton’s procedure, = 14 for CRAE model (Morton, 1983),
b2 - a constant in Morton’s procedure, = 1.2 for CRAE model (Morton, 1983),
gammaps - Produce of Psychrometric constant and atmospheric pressure as sea
level, = 0.66 mbar. degree Celcius^-1 for T >= 0 degree Celcius, = 0.66/1.15
mbar. degree Celcius^-1 for T < 0 degree Celcius (Morton, 1983),

alphaMo - a constant in Morton’s procedure, = 17.27 when T >= 0 degree Cel-

cius, = 21.88 when T < 0 degree Celcius (Morton, 1983),
betaMo - a constant in Morton’s procedure, = 237.3 degree Celcius when T >=
0 degree Celcius, = 265.5 degree Celcius, when T < 0 degree Celcius (Morton,
1983),
sigmaMo - Stefan-Boltzmann constant in Morton’s procedure, = 5.67e-08 W.m^-
2.K^-4 (Morton, 1983),
ET.MortonCRAE 37

lambdaMo - Latent heat of vaporisation in Morton’s procedure, = 28.5W.day.kg^-

1 when T >= 0 degree Celcius, = 28.5*1.15W.day.kg^-1 when T < 0 degree Cel-
cius,

ts Must be either monthly or annual, which indicates the disired time step that the
output ET estimates should be on. Default is monthly.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
est Must be either potential ET, wet areal ET or actual areal ET:
potential ET proceeds to estimating potential evapotranspiration;
wet areal ET proceeds to estimating wet-environmental areal evapotranspira-
tion;
actual areal ET proceeds to estimating actual areal evapotranspiraion.
Default is potential ET.
Tdew Must be T or F, indicating if real data of dew point temperature is used for
calculating the radiation in Morton’s formulations, if T the data will be used
and if F the dew point temperature will be calculated from data of daily vapour
pressure. Default is T for using actual dew point temperature data.
alpha Only needed if argument solar has value of data.
Any numeric value between 0 and 1 (dimensionless), albedo of evaporative sur-
face representing the portion of the incident radiation that is reflected back at the
surface.
Default is NULL in line with the default use of sunshine hours to estimate solar
radiation (i.e. argument solar is sunshine hours.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated (i.e. the value of argument est)
- Option for calculating solar radiation (i.e. the value of argument solar)
- If the actual dew point temperature data are used (i.e. the value of argument
Tdew)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
38 ET.MortonCRAE

save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The type of evapotranspiration calculated can be selected through argument est, please see Arguments
for details. The alternative calculation options can be selected through argument solar and Tdew,
please see Arguments for details.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Morton CRAE potential evapotranspiration,

wet-environment areal evapotranspiration or actual areal evapotranspiration.
ET.Monthly Monthly aggregated estimations of Morton CRAE potential evapotranspiration,
wet-environment areal evapotranspiration or actual areal evapotranspiration.
ET.Annual A zoo object containing annually aggregated estimations of Morton CRAE po-
tential evapotranspiration, wet-environment areal evapotranspiration or actual
areal evapotranspiration.
ET.MonthlyAve A zoo object containing monthly averaged estimations of daily Morton CRAE
potential evapotranspiration, wet-environment areal evapotranspiration or actual
areal evapotranspiration.
ET.AnnualAve A zoo object containing annually averaged estimations of daily Morton CRAE
potential evapotranspiration, wet-environment areal evapotranspiration or actual
areal evapotranspiration.
ET_formulation Name of the formulation used which equals to MortonCRAE.
ET_type Type of the estimation obtained which is either Potential Evapotranspiration,
Wet-environment Areal Evapotranspiration and Actual Areal Evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.
message6 A message to inform the users about if actual dew point temperature has been
used in the calculations or alternative calculations has been performed without
dew point temperature data.

Author(s)
Danlu Guo

References
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Morton, F.I. 1983, Operational estimates of areal evapotranspiration and their significance to the
science and practice of hydrology. Journal of Hydrology, vol. 66, no. 1-4, pp. 1-76.
ET.MortonCRWE 39

See Also
processeddata,defaultconstants,constants,ET.MortonCRWE

Examples
# Use processed existing data set and constants from
# kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.MortonCRAE under the generic function ET

results <- ET.MortonCRAE(processeddata, constants, ts="monthly",
est="potential ET", solar="sunshine hours", Tdew= TRUE,
alpha = NULL, message="yes", AdditionalStats="yes", save.csv="no")

ET.MortonCRWE Morton CRWE Formulation

Description
Implementing the Morton CRWE formulation for estimating potential evapotranspiration or shallow
lake evaporation.

Usage
## S3 method for class 'MortonCRWE'
ET(data, constants, ts="monthly", est="potential ET",
solar="sunshine hours", Tdew= T, alpha = NULL, message="yes", AdditionalStats="yes",
save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Morton CRWE formulation:
Tmax, Tmin, Tdew (degree Celcius) or va or RHmax and RHmin, Rs (Megajoules
per sqm) or n (hour) or Cd (okta)
constants A list named constants consists of constants required for the calculation of
Morton CRWE formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lat_rad - latitude in radians,
PA - annual precipitation in mm, required when precipitation data is not avail-
able,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1,
lat - latitude in degrees,
epsilonMo - surface emissivity = 0.92 (Morton, 1986),
fz - A constant in Morton’s procedure = 25.0 Wm^-2.mbar^-1 for T >= 0 de-
gree Celcius, and = 28.75 Wm^-2.mbar^-1 for T >= 0 degree Celcius for CRWE
40 ET.MortonCRWE

model (Morton, 1986),

b0 - A constants in Morton’s procedure, = 1.12 for CRWE model, (Morton,
1986) b1 - A constant in Morton’s procedure, = 13 for CRWE model (Morton,
1986),
b2 - A constant in Morton’s procedure, = 1.12 for CRWE model (Morton, 1986),
gammaps - Produce of Psychrometric constant and atmospheric pressure as sea
level, = 0.66 mbar. degree Celcius^-1 for T >= 0 degree Celcius, = 0.66/1.15
mbar. degree Celcius^-1 for T < 0 degree Celcius (Morton, 1983),

alphaMo - a constant in Morton’s procedure, = 17.27 when T >= 0 degree Cel-

cius, = 21.88 when T < 0 degree Celcius (Morton, 1983),
betaMo - a constant in Morton’s procedure, = 237.3 degree Celcius when T >=
0 degree Celcius, = 265.5 degree Celcius, when T < 0 degree Celcius (Morton,
1983),
sigmaMo - Stefan-Boltzmann constant in Morton’s procedure, = 5.67e-08 W.m^-
2.K^-4 (Morton, 1983),
lambdaMo - Latent heat of vaporisation in Morton’s procedure, = 28.5W.day.kg^-
1 when T >= 0 degree Celcius, = 28.5*1.15W.day.kg^-1 when T < 0 degree Cel-
cius,

ts Must be either monthly or annual, which indicates the disired time step that the
output ET estimates should be on. Default is monthly.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
est Must be either potential ET or shallow lake ET:
potential ET proceeds to estimating potential evapotranspiration;
shallow lake ET proceeds to estimating shallow lake evaporation.
Default is potential ET.
Tdew Must be T or F, indicating if real data of dew point temperature is used for
calculating the radiation in Morton’s formulations, if T the data will be used
and if F the dew point temperature will be calculated from data of daily vapour
pressure. Default is T for using actual dew point temperature data.
alpha Only needed if argument solar has value of data.
Any numeric value between 0 and 1 (dimensionless), albedo of evaporative sur-
face representing the portion of the incident radiation that is reflected back at the
surface.
Default is NULL in line with the default use of sunshine hours to estimate solar
radiation (i.e. argument solar is sunshine hours.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
ET.MortonCRWE 41

- ET model name and ET quantity estimated (i.e. the value of argument est)
- Option for calculating solar radiation (i.e. the value of argument solar)
- If the actual dew point temperature data are used (i.e. the value of argument
Tdew)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The type of evapotranspiration calculated can be selected through argument est, please see Arguments
for details. The alternative calculation options can be selected through argument solar and Tdew,
please see Arguments for details.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of MortonCRWE potential evapotranspiration or

shallow lake evaporation.
ET.Monthly Monthly aggregated estimations of MortonCRWE potential evapotranspiration
or shallow lake evaporation.
ET.Annual Annually aggregated estimations of MortonCRWE potential evapotranspiration
or shallow lake evaporation.
ET.MonthlyAve Monthly averaged estimations of daily MortonCRWE potential evapotranspira-
tion or shallow lake evaporation.
ET.AnnualAve Annually averaged estimations of daily MortonCRWE potential evapotranspira-
tion or shallow lake evaporation.
ET_formulation Name of the formulation used which equals to MortonCRWE.
ET_type Type of the estimation obtained which is either Potential Evapotranspiration
or Shallow Lake Evaporation.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.
message6 A message to inform the users about if actual dew point temperature has been
used in the calculations or alternative calculations has been performed without
dew point temperature data.
42 ET.Penman

Author(s)

Danlu Guo

References

McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Morton, F.I. 1983, Operational estimates of lake evaporation. Journal of Hydrology, vol. 66, no.
1-4, pp. 77-100.

See Also

processeddata,defaultconstants,constants,ET.MortonCRWE

Examples

# Use processed existing data set and constants from

# kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.MortonCRWE under the generic function ET

results <- ET.MortonCRWE(processeddata, constants, ts="monthly",
est="potential ET", solar="sunshine hours", Tdew= TRUE,
alpha = NULL, message="yes", AdditionalStats="yes", save.csv="no")

ET.Penman Penman Formulation

Description

Implementing the Penman formulation for estimating open-water evaporation or potential evapo-
transpiration

Usage

## S3 method for class 'Penman'

ET(data, constants, ts="daily", solar="sunshine hours",
wind="yes", windfunction_ver=1948, alpha=0.08, z0=0.001, message="yes",
AdditionalStats="yes", save.csv="no", ...)
ET.Penman 43

Arguments
data A list which contains the following items (climate variables) required by Pen-
man formulation:
Tmax, Tmin, RHmax, RHmin, Rs or n or Cd, u2 or uz
constants A list named constants consists of constants required for the calculation of
Penman formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
z - height of wind instrument in m,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1.

The following constants are also required when argument solar has value of
sunshine hours:
as - only for when cloud data is used for calculating radiation i.e. solar = "cloud"
- fraction of extraterrestrial radiation reaching earth on sunless days,
bs - only for when cloud data is used for calculating radiation i.e. solar = "cloud"
- difference between fracion of extraterrestrial radiation reaching full-sun days
and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
wind Must be either yes or no.
yes indicates that the calculation will use real data of wind speed;
no indicates that the alternative calculation without using wind data will be used
in Penman formulation (Valiantzas 2006, Equation33).
Default is yes.
windfunction_ver
The version of Penman wind function that will be used within the Penman for-
mulation. Must be either 1948 or 1956.
1948 is for applying the Penman’s 1948 wind function (Penman, 1948);
1956 is for applying the Penman’s 1956 wind function (Penman, 1956) Default
is 1948.
alpha Any numeric value between 0 and 1 (dimensionless), albedo of evaporative sur-
face representing the portion of the incident radiation that is reflected back at the
surface.
Default is 0.08 for open-water surface which is for the calculation of Penman
44 ET.Penman

open-water evaporation, all other values will trigger the calculation of Penman
potential evapotranspriation.
z0 Any value (metres), roughness height of the evaporative surface.
Default is 0.001 for open-water surface which is for the calculation of Penman
open-water evaporation, all other values will trigger the calculation of Penman
potential evapotranspriation.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Evaporative surface with values of albedo and roughness height
- Option for calculating solar radiation (i.e. the value of argument solar)
- If actual wind data has been used for calculation (i.e. the value of argument
wind) and which version of Penman wind function has been used (i.e. the value
of argument windfunction_ver)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The alternative calculation options can be selected through arguments solar, wind and windfunction_ver,
please see Arguments for details.
User-defined evaporative surface is allowed through arguments alpha and z0, please see Arguments
for details.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Penman open-water evaporation or potential

evapotranspiration.
ET.Monthly Monthly aggregated estimations of Penman open-water evaporation or potential
evapotranspiration.
ET.Annual Annually aggregated estimations of Penman open-water evaporation or potential
evapotranspiration.
ET.MonthlyAve Monthly averaged estimations of daily Penman open-water evaporation or po-
tential evapotranspiration.
ET.Penman 45

ET.AnnualAve Annually averaged estimations of daily Penman open-water evaporation or po-

tential evapotranspiration.
ET_formulation Name of the formulation used which equals to Penman.
ET_type Type of the estimation obtained which is either Open-water Evaporation or
Potential Evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.
message2 A message to inform the users about if actual wind data has been used in the
calculations or alternative calculations has been performed without wind data,
and which version of the Penman wind function has been used.

Author(s)

Danlu Guo

References

McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Penman, H. L. 1948. Natural evaporation from open water, bare soil and grass. Proceedings of the
Royal Society of London. Series A. Mathematical and Physical Sciences, 193, 120-145.
Valiantzas, J. D. 2006. Simplified versions for the Penman evaporation equation using routine
weather data. Journal of Hydrology, 331, 690-702.
Penman, H. L. 1956. Evaporation: An introductory survey. Netherlands Journal of Agricultural
Science, 4, 9-29.

See Also

ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from
# kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.Penman under the generic function ET

results <- ET.Penman(processeddata, constants, ts="daily",
solar="sunshine hours", wind="yes",
windfunction_ver = "1948", alpha = 0.08, z0 = 0.001,
message="yes", AdditionalStats="yes", save.csv="no")
46 ET.PenmanMonteith

ET.PenmanMonteith Penman-Monteith Formulation

Description
Implementing the Penman-Monteith formulation (including the method for FAO-56 hypothetical
short grass and the method for ASCE-EWRI Standardised crop) for estimating reference crop evap-
otranspiration

Usage
## S3 method for class 'PenmanMonteith'
ET(data, constants, ts="daily", solar="sunshine hours",
wind="yes", crop="short", message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list which contains the following items (climate variables) required by Penman-
Monteith formulation:
Tmax, Tmin, RHmax, RHmin, Rs or n or Cd, u2 or uz
constants A list named constants consists of constants required for the calculation of
Penman-Monteith formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
z - height of wind instrument in m,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1.
G - soil heat flux in MJ.m^-2.day^-1, = 0 when using daily time step.
The following constants are also required when argument solar has value of
sunshine hours:
as - only for when cloud data is used for calculating radiation i.e. solar = "cloud"
- fraction of extraterrestrial radiation reaching earth on sunless days,
bs - only for when cloud data is used for calculating radiation i.e. solar = "cloud"
- difference between fracion of extraterrestrial radiation reaching full-sun days
and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
ET.PenmanMonteith 47

wind Must be either yes or no.

yes indicates that the calculation will use real data of wind speed;
no indicates that the alternative calculation without using wind data will be used
in Penman formulation (Valiantzas 2006, Equation33).
Default is yes.
crop Must be either short or tall.
short indicates that the method for FAO-56 hypothetical short grass will be ap-
plied (Allen et al., 1998, Equation 6);
tall indicates that the method for ASCE-EWRI Standardised crop will be ap-
plied (ASCE, 2005, Equation 1, Table 1).
Default is short.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Evaporative surface with values of albedo, surface resistance, crop height and
roughness height
- Option for calculating solar radiation (i.e. the value of argument solar)
- If actual wind data has been used for calculation (i.e. the value of argument
wind)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The alternative calculation options can be selected through arguments solar and wind, please see
Arguments for details.
User-defined evaporative surface is allowed through arguments crop, please see Arguments for
details.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Penman-Monteith rerference crop evapotran-

spiration.
ET.Monthly Monthly aggregated estimations of Penman-Monteith rerference crop evapo-
transpiration.
48 ET.PenmanMonteith

ET.Annual Annually aggregated estimations of Penman-Monteith rerference crop evapo-

transpiration.
ET.MonthlyAve Monthly averaged estimations of daily Penman-Monteith rerference crop evap-
otranspiration.
ET.AnnualAve Annually averaged estimations of daily Penman-Monteith rerference crop evap-
otranspiration.
ET_formulation Name of the formulation used which equals to either Penman-Monteith FAO56
or Penman-Monteith ASCE-EWRI Standardised.
ET_type A character string containing the type of the estimation obtained which is Reference
Crop Evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.
message2 A message to inform the users about if actual wind data has been used in the
calculations or alternative calculations has been performed without wind data.

Author(s)

Danlu Guo

References

McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Allen, R. G., Pereira, L. S., Raes, D. & Smith, M. 1998. Crop evapotranspiration-Guidelines for
computing crop water requirements-FAO Irrigation and drainage. paper 56. FAO, Rome, 300,
6541.
Allen, R. G. 2005. The ASCE standardized reference evapotranspiration equation. Amer Society
of Civil Engineers.

See Also

ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.PenmanMonteith under the generic function ET

results <- ET.PenmanMonteith(processeddata, constants, ts="daily", solar="sunshine hours",
wind="yes", crop = "short", message="yes", AdditionalStats="yes", save.csv="no")
ET.PenPan 49

ET.PenPan PenPan Formulation

Description
Implementing the PenPan formulation for Class-A pan evaporation.

Usage
## S3 method for class 'PenPan'
ET(data, constants, ts="daily", solar="sunshine hours",
alpha=0.23, est="potential ET", pan_coeff=0.71, overest= F, message="yes",
AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
PenPan formulation:
Tmax, Tmin (degree Celcius), RHmax, RHmin (per cent), Rs (Megajoules per
sqm) or n (hour) or Cd (okta), u2 or uz (meter per second)
constants A list named constants consists of constants required for the calculation of
PenPan formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
z - height of wind instrument in m,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1,
lat - latitude in degrees,
alphaA - albedo for Class-A pan,
ap - a constant in PenPan = 2.4.

The following constants are also required when argument solar has value of
sunshine hours:
as - fraction of extraterrestrial radiation reaching earth on sunless days,
bs - difference between fracion of extraterrestrial radiation reaching full-sun
days and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
50 ET.PenPan

monthly precipitation indicates that solar radiation is to be calculated di-

rectly from monthly precipitation.
Default is sunshine hours.
alpha Any numeric value between 0 and 1 (dimensionless), albedo of surface sur-
rounding the evaporation pan representing the portion of the incident radiation
that is reflected back at the surface.
Default is 0.23 for surface covered with short reference crop.
overest Must be T or F, indicating if adjustment for the overestimation (i.e. divided
by 1.078) of Class-A pan evaporation for Australian data is applied in PenPan
formulation.
Default is F for no adjustment.
est Must be either pan or potential ET to specify if estimation for the Class-A pan
evaporation or potential evapotranspriation is performed.
Default is potential ET for estimating potential evapotranspriation.
pan_coeff Only required if argument est has value of potential ET, which defines the
pan coefficient used to adjust the estimated pan evaporation to the potential ET
required.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated (i.e. the value of argument est),
and the value of pan coefficient (only for when potential ET is estimated)
- Evaporative surface with values of albedo
- Option for calculating solar radiation (i.e. the value of argument solar)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details

The alternative calculation options can be selected through argument solar, please see Arguments
for details.
User-defined evaporative surface is allowed through argument alpha, please see Arguments for de-
tails.
Adjustment for overestimation on the estimations are available through argument height, please
see Arguments for details.
ET.PenPan 51

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of PenPan Class-A pan evaporation/potential evap-

otranspiration.
ET.Monthly Monthly aggregated estimations of PenPan Class-A pan evaporation/potential
evapotranspiration.
ET.Annual Annually aggregated estimations of PenPan Class-A pan evaporation/potential
evapotranspiration.
ET.MonthlyAve Monthly averaged estimations of daily PenPan Class-A pan evaporation/potential
evapotranspiration.
ET.AnnualAve Annually averaged estimations of daily PenPan Class-A pan evaporation/potential
evapotranspiration.
ET_formulation Name of the formulation used which equals to PenPan.
ET_type Type of the estimation obtained which is Class-A Pan Evaporation or Potential
Evapotranspiration depending on the value of est.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.

Author(s)
Danlu Guo

References
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Rotstayn, L. D., Roderick, M. L. & Farquhar, G. D. 2006. A simple pan-evaporation model for
analysis of climate simulations: Evaluation over Australia. Geophysical Research Letters, 33.

See Also
ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from
# kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.PenPan under the generic function ET

results <- ET.PenPan(processeddata, constants, ts="daily",
solar="sunshine hours", alpha=0.23,
est="potential ET", pan_coeff=0.71, overest= FALSE,
message="yes", AdditionalStats="yes", save.csv="no")
52 ET.PriestleyTaylor

ET.PriestleyTaylor Priestley-Taylor Formulation

Description
Implementing the Priestley-Taylor formulation for potential evaporation

Usage
## S3 method for class 'PriestleyTaylor'
ET(data, constants, ts="daily", solar="sunshine hours", alpha=0.23,
message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list which contains the following items (climate variables) required by Priestley-
Taylor formulation:
Tmax, Tmin (degree Celcius), RHmax, RHmin (per cent), Rs (Megajoules per
sqm) or n (hour) or Cd (okta)
constants A list named constants consists of constants required for the calculation of
Priestley-Taylor formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1,
alphaPT - Priestley-Taylor coefficient = 1.26 for Priestley-Taylor model (Priest-
ley and Taylor, 1972)
G - soil heat flux in MJ.m^-2.day^-1, = 0 when using daily time step.

The following constants are also required when argument solar has value of
sunshine hours:
as - fraction of extraterrestrial radiation reaching earth on sunless days,
bs - difference between fracion of extraterrestrial radiation reaching full-sun
days and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
ET.PriestleyTaylor 53

alpha Any numeric value between 0 and 1 (dimensionless), albedo of evaporative sur-
face representing the portion of the incident radiation that is reflected back at the
surface.
Default is 0.23 for surface covered with short reference crop, which is for the
calculation of Priestly-Taylor reference crop evaporation.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Evaporative surface with values of albedo
- Option for calculating solar radiation (i.e. the value of argument solar)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The alternative calculation options can be selected through argument solar, please see Arguments
for details.
User-defined evaporative surface is allowed through argument alpha, please see Arguments for
details.

Value
The function generates a list containing the following components, which is saved into a csv file
named as ET_PriestleyTaylor.csv in the working directory:

ET.Daily Daily aggregated estimations of Priestley-Taylor potential evaporation.

ET.Monthly Monthly aggregated estimations of Priestley-Taylor potential evaporation.
ET.Annual Annually aggregated estimations of Priestley-Taylor potential evaporation.
ET.MonthlyAve Monthly averaged estimations of daily Priestley-Taylor potential evaporation.
ET.AnnualAve Annually averaged estimations of daily Priestley-Taylor potential evaporation.
ET_formulation A character string containing the name of the formulation used which equals to
Priestley-Taylor.
ET_type Type of the estimation obtained which is Potential Evaporation.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.
54 ET.Romanenko

Author(s)
Danlu Guo

References
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Priestley, C. & Taylor, R. 1972, On the assessment of surface heat flux and evaporation using large-
scale parameters’. Monthly Weather Review, vol. 100, no. 2, pp. 81-92.

See Also
ET,processeddata,defaultconstants,constants

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.PriestleyTaylor under the generic function ET

results <- ET.PriestleyTaylor(processeddata, constants, ts="daily",
solar="sunshine hours", alpha=0.23, message="yes", AdditionalStats="yes", save.csv="no")

ET.Romanenko Romanenko Formulation

Description
Implementing the Romanenko formulation for estimating potential evapotranspiration.

Usage
## S3 method for class 'Romanenko'
ET(data, constants = NULL, ts="daily",
message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Romanenko formulation:
Tmax, Tmin (degree Celcius), RHmax, RHmin (per cent)
constants Dummy argument with a NULL value.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
ET.Romanenko 55

message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
This formulation provides a single calculation method with no alternatives available.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Romanenko potential evapotranspiration.

ET.Monthly Monthly aggregated estimations of Romanenko potential evapotranspiration.
ET.Annual Annually aggregated estimations of Romanenko potential evapotranspiration.
ET.MonthlyAve Monthly averaged estimations of daily Romanenko potential evapotranspiration.
ET.AnnualAve Annually averaged estimations of daily Romanenko potential evapotranspira-
tion.
ET_formulation Name of the formulation used which equals to Romanenko.
ET_type Type of the estimation obtained which is Potential Evapotranspiration.

Author(s)
Danlu Guo

References
Oudin, L., Hervieu, F., Michel, C., Perrin, C., Andreassian, V., Anctil, F.Loumagne, C. 2005,
Which potential evapotranspiration input for a lumped rainfall-runoff model?: Part 2-Towards a
simple and efficient potential evapotranspiration model for rainfall-runoff modelling. Journal of
Hydrology, vol. 303, no. 1-4, pp. 290-306.

See Also
ET,processeddata
56 ET.SzilagyiJozsa

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.Romanenko under the generic function ET

results <- ET.Romanenko(processeddata, ts="daily", message="yes",
AdditionalStats="yes", save.csv="no")

ET.SzilagyiJozsa Szilagyi-Jozsa Formulation

Description
Implementing the Szilagyi-Jozsa formulation for estimating actual evapotranspiration

Usage
## S3 method for class 'SzilagyiJozsa'
ET(data, constants, ts="daily", solar="sunshine hours", wind="yes",
windfunction_ver=1948, alpha=0.23, z0=0.2, message="yes", AdditionalStats="yes",
save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Szilagyi-Jozsa formulation:
Tmax, Tmin (degree Celcius), RHmax, RHmin (per cent), Rs (Megajoules per
sqm) or n (hour) or Cd (okta), u2 or uz (meter per second)
constants A list named constants consists of constants required for the calculation of
Szilagyi-Jozsa formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
z - height of wind instrument in m,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1.

The following constants are also required when argument solar has value of
sunshine hours:
as - fraction of extraterrestrial radiation reaching earth on sunless days,
bs - difference between fracion of extraterrestrial radiation reaching full-sun
days and that on sunless days.
ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
ET.SzilagyiJozsa 57

solar Must be either data, sunshine hours, cloud or monthly precipitation:

data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
wind Must be either yes or no.
yes indicates that the calculation will use real data of wind speed;
no indicates that the alternative calculation without using wind data will be used
in Penman formulation (Valiantzas 2006, Equation33), which is required in the
Szilagyi-Jozsa model.
Default is yes.
windfunction_ver
The version of Penman wind function that will be used within the Penman for-
mulation. Must be either 1948 or 1956.
1948 is for applying the Penman’s 1948 wind function (Penman, 1948);
1956 is for applying the Penman’s 1956 wind function (Penman, 1956) Default
is 1948.
alpha Any numeric value between 0 and 1 (dimensionless), albedo of evaporative sur-
face representing the portion of the incident radiation that is reflected back at the
surface.
Default is 0.23 for short reference crop.
z0 Any value (metres), roughness height of the evaporative surface.
Default is 0.23 for short reference crop.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Evaporative surface with values of albedo, as well as the roughness height
- Option for calculating solar radiation (i.e. the value of argument solar)
- If actual wind data has been used for calculation (i.e. the value of argument
wind) and which version of Penman wind function has been used (i.e. the value
of argument windfunction_ver)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.
58 ET.SzilagyiJozsa

Details
The alternative calculation options can be selected through arguments solar, wind and windfunction_ver,
please see Arguments for details.
User-defined evaporative surface is allowed through arguments alpha and z0, please see Arguments
for details.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Szilagyi-Jozsa actual evapotranspiration.

ET.Monthly Monthly aggregated estimations of Szilagyi-Jozsa actual evapotranspiration.
ET.Annual Annually aggregated estimations of Szilagyi-Jozsa actual evapotranspiration.
ET.MonthlyAve Monthly averaged estimations of daily Szilagyi-Jozsa actual evapotranspiration.
ET.AnnualAve Annually averaged estimations of daily Szilagyi-Jozsa actual evapotranspira-
tion.
ET_formulation Name of the formulation used which equals to Szilagyi-Jozsa.
ET_type A character string containing the type of the estimation obtained which is Actual
Evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.
message2 A message to inform the users about if actual wind data has been used in the
calculations or alternative calculations has been performed without wind data,
and which version of the Penman wind function has been used.

Author(s)
Danlu Guo

References
Szilagyi, J. 2007. On the inherent asymmetric nature of the complementary relationship of evapo-
ration. Geophysical Research Letters, 34, L02405.
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Penman, H. L. 1948. Natural evaporation from open water, bare soil and grass. Proceedings of the
Royal Society of London. Series A. Mathematical and Physical Sciences, 193, 120-145.
Valiantzas, J. D. 2006. Simplified versions for the Penman evaporation equation using routine
weather data. Journal of Hydrology, 331, 690-702.
Penman, H. L. 1956. Evaporation: An introductory survey. Netherlands Journal of Agricultural
Science, 4, 9-29.
ET.Turc 59

See Also
ET,processeddata,defaultconstants,constants,ET.Penman

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.SzilagyiJozsa under the generic function ET

results <- ET.SzilagyiJozsa(processeddata, constants, ts="daily",
solar="sunshine hours", wind="yes", windfunction_ver=1948, alpha=0.23, z0=0.2,
message="yes", AdditionalStats="yes", save.csv="no")

ET.Turc Turc Formulation

Description
Implementing the Turc formulation for estimating reference crop evapotranspiration.

Usage
## S3 method for class 'Turc'
ET(data, constants, ts="daily", solar="sunshine hours", humid= F,
message="yes", AdditionalStats="yes", save.csv="no", ...)

Arguments
data A list of data which contains the following items (climate variables) required by
Turc formulation:
Tmax, Tmin (degree Celcius), Rs (Megajoules per sqm) or n (hour) or Cd (okta)
constants A list named constants consists of constants required for the calculation of
Turc formulation which must contain the following items:
Elev - ground elevation above mean sea level in m,
lambda - latent heat of vaporisation = 2.45 MJ.kg^-1,
lat_rad - latitude in radians,
Gsc - solar constant = 0.0820 MJ.m^-2.min^-1,
sigma - Stefan-Boltzmann constant = 4.903*10^-9 MJ.K^-4.m^-2.day^-1.

The following constants are also required when argument solar has value of
sunshine hours:
as - fraction of extraterrestrial radiation reaching earth on sunless days,
bs - difference between fracion of extraterrestrial radiation reaching full-sun
days and that on sunless days.
60 ET.Turc

ts Must be either daily, monthly or annual, which indicates the disired time step
that the output ET estimates should be on. Default is daily.
solar Must be either data, sunshine hours, cloud or monthly precipitation:
data indicates that solar radiation data is to be used directly for calculating evap-
otranspiration;
sunshine hours indicates that solar radiation is to be calculated using the real
data of sunshine hours;
cloud sunshine hours is to be estimated from cloud data;
monthly precipitation indicates that solar radiation is to be calculated di-
rectly from monthly precipitation.
Default is sunshine hours.
humid Must be T or F, indicating if adjustment for non-humid conditions is applied in
Turc formulation (Alexandris et al., 2008, Equation 5b).
Default is F for no adjustment.
message Must be either yes or no, indicating whether message should be printed for
calculation summary including the following elements:
- ET model name and ET quantity estimated
- Evaporative surface
- Option for calculating solar radiation (i.e. the value of argument solar)
- if adjustment for non-humid conditions has been applied (i.e. the value of
argument humid)
- Time step of the output ET estimates (i.e. the value of argument ts)
- Units of the output ET estimates
- Time duration of the ET estimation
- Number of ET estimates obtained in the entire time-series
- Basic statistics of the estimated ET time-series including mean, max and min
values.
AdditionalStats
"yes" or "no" indicating whether monthly averaged and annual averaged ET
should be calculated.
save.csv Must be either yes or no, indicating whether a .csv of ET estimates should be
saved to working directory.
... Dummy for generic function, no need to define.

Details
The alternative calculation options can be selected through argument solar, please see Arguments
for details.
Humidity adjustment for the estimations is available through argument humid, please see Arguments
for details.

Value
The function generates a list containing the following components:

ET.Daily Daily aggregated estimations of Turc reference crop evapotranspiration.

ET.Turc 61

ET.Monthly Monthly aggregated estimations of Turc reference crop evapotranspiration.

ET.Annual Annually aggregated estimations of Turc reference crop evapotranspiration.
ET.MonthlyAve Monthly averaged estimations of daily Turc reference crop evapotranspiration.
ET.AnnualAve Annually averaged estimations of daily Turc reference crop evapotranspiration.
ET_formulation Name of the formulation used which equals to Turc.
ET_type Type of the estimation obtained which is Reference Crop Evapotranspiration.
message1 A message to inform the users about how solar radiation has been calculated by
using which data.
message4 A message to inform the users about if adjustment for non-humid conditions has
been applied to calculated Turc reference crop evapotranspiration.

Author(s)

Danlu Guo

References

McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Turc, L. 1961, Estimation of irrigation water requirements, potential evapotranspiration: a simple
climatic formula evolved up to date. Ann. Agron, vol. 12, no. 1, pp. 13-49.
Alexandris, S., Stricevic, R.Petkovic, S. 2008, Comparative analysis of reference evapotranspira-
tion from the surface of rainfed grass in central Serbia, calculated by six empirical methods against
the Penman-Monteith formula. European Water, vol. 21, no. 22, pp. 17-28.

See Also

ET,processeddata,defaultconstants,constants

Examples

# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.Turc under the generic function ET

results <- ET.Turc(processeddata, constants, ts="daily", solar="sunshine hours", humid= FALSE,
message="yes", AdditionalStats="yes", save.csv="no")
62 ETComparison

ETComparison Compare esimtated evapotranspiration among multiple sets of result

Description
Produce comparison plots for results and statistics from different estimations produced by using
different formulations and/or different input data. The number of different sets of results can be
between 2 and 7. Plotting type can be selected among daily aggregation, monthly aggregation,
annual aggregation, monthly average and annual average. For each type three comparison plots will
be produced including time series, non-exceedance probability and box plot.

Usage
ETComparison(results1, results2, results3 = NULL, results4 = NULL, results5 = NULL,
results6 = NULL, results7 = NULL, labs, Sdate = NULL, Edate = NULL,
type = "Monthly", ylim = rep(NA,2))

Arguments
results1 A list named results which has been derived from function ET which can be
from any model such as Penman, Penman-Monteith or Priestley-Taylor.
results2 A list named results which has been derived from function ET which can be
from any model such as Penman, Penman-Monteith or Priestley-Taylor.
results3 A list named results which has been derived from function ET which can be
from any model such as Penman, Penman-Monteith or Priestley-Taylor.
The default is NULL if the user requires the comparison between only two sets
of results.
results4 A list named results which has been derived from function ET which can be
from any model such as Penman, Penman-Monteith or Priestley-Taylor.
The default is NULL if the user requires the comparison among only three sets
of results.
results5 A list named results which has been derived from function ET which can be
from any model such as Penman, Penman-Monteith or Priestley-Taylor.
The default is NULL if the user requires the comparison among only four sets
of results.
results6 A list named results which has been derived from function ET which can be
from any model such as Penman, Penman-Monteith or Priestley-Taylor.
The default is NULL if the user requires the comparison among only five sets of
results.
results7 A list named results which has been derived from function ET which can be
from any model such as Penman, Penman-Monteith or Priestley-Taylor.
The default is NULL if the user requires the comparison among only six sets of
results.
ETComparison 63

labs A character vector with the length equal to the number of sets of results to com-
pare, defining the labels for the comparison plots
Sdate Only used when argument type is Daily, Monthly or Annual to define the start
date for the plotting windows, which can be defined by user in the format YYYY-
MM-DD; if missing the default is the first day of data is used.
Edate Only used when argument type is Daily, Monthly or Annual to define the end
date for the plotting windows, which can be defined by user in the format YYYY-
MM-DD; if missing the default is the last day of data is used.
ylim A numeric vector of length 2 defining the lower and upper limit of the y-axis for
plotting, if missing the default is from 0 to 1.5 times of maximum value from
the first set of result that is used to compare with others.
type A character string indicating the type of plot produced, can be one of the fol-
lowing:
Daily - comparison plots of estimated daily evapotranspiration;
Monthly - comparison plots of monthly aggregated evapotranspiration;
Annual - comparison plots of annually aggregated evapotranspiration;
MonthlyAve - comparison plots of monthly averaged daily evapotranspiration;
AnnualAve - comparison plots of annually averaged daily evapotranspiration.

Value
Three plots are generated for each type of comparison plot selected, including:
1) time series plot of the estimated/aggregated/averaged values from each set of result;
2) non-exceedance plot of the distribution of estimated/aggregated/averaged values from each set
of result;
3) box plot of the distribution of estimated/aggregated/averaged values from each set of result.

Author(s)
Danlu Guo

See Also
ETPlot

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.Penman under the generic function ET

results_Penman <- ET.Penman(processeddata, constants, ts="daily", solar="sunshine hours",
wind="yes", windfunction_ver = "1948", alpha = 0.08, z0 = 0.001, save.csv="no")

# Call ET.PenmanMonteith under the generic function ET

results_PenmanMonteith <- ET.PenmanMonteith(processeddata, constants, ts="daily",
solar="sunshine hours", wind="yes", crop = "short", save.csv="no")
64 ETForcings

# Plot the estimated Penman open-water evaporation against average temperature

ETComparison(results_Penman, results_PenmanMonteith, type = "Monthly", ylim=c(0,400),
labs=c("Penman","PenmanMonteith"))

ETForcings Plot esimtated evapotranspiration with climate variables

Description
Produce plot of daily, monthly and annual averaged estimated evapotranspiration with selected
climate variables of the same time step.

Usage
ETForcings(data, results, forcing)

Arguments
data A list of data named data which must contain a component with the name of a
climate variable that the estimated evapotranspiration should be plotted against,
see forcing.
results A list named results which has been derived from function ET.
forcing A character string as the name of a climate variable that the estimated evapo-
transpiration should be plotted against, can be any of:
Tmax - maximum temperature,
Tmin - minimum temperature,
u2 - average wind speed at 2m,
uz - average wind speed,
Rs - solar radiation,
n - daily sunshine hours,
Precip - precipitation,
Epan - Class-A pan evaporation,
RHmax - maximum relative humidity,
RHmin - minimum relative humidity,
Tdew - average dew point temeprature.

Value
Three plots are generated for the response of calculated evapotranspiration to each climate variable,
including:
1) daily evapotranspiration estimate vs. daily average temperature;
2) monthly mean daily evaporationion estimate vs. monthly average temperature;
3) annual mean daily evaporationion estimate vs. annual average temperature.
ETPlot 65

Author(s)
Danlu Guo

See Also
ETPlot

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.Penman under the generic function ET

results <- ET.Penman(processeddata, constants, ts="daily", solar="sunshine hours",
wind="yes", windfunction_ver = "1948", alpha = 0.08, z0 = 0.001, save.csv="no")

# Plot the estimated Penman open-water evaporation against average temperature

ETForcings(processeddata, results, forcing = "Tmax")

ETPlot Plot the daily, monthly and annual aggregations of esimtated evapo-
transpiration

Description
Produce plot of aggregated estimations of evapotranspiration in daily, monthly and annual steps, or
averaged daily estimations in monthly or annual steps.

Usage
ETPlot(results, type = "Aggregation", OBS, OBSplot, Sdate = time(results$ET.Daily)[1],
Edate = time(results$ET.Daily)[length(results$ET.Daily)])

Arguments
results A list named results which has been derived from function ET..().
type A character string of either Aggregation or Average to indicate the type of plot
required. The default is Aggregation. For aggregation plot the user can define
the start and end date of plotting or by default using the calculation period for
plotting. For average plot the plotting period equals to the calculation period.
OBS A list named OBS which has been derived from function ReadOBSEvaporation.
OBSplot Must be eith TRUE or FALSE. TRUE indicates that the observed evaporation
will be plotted together with the estimations and FALSE indicates that the ob-
servations will not be shown on the plots.
66 ETPlot

Sdate Only used when type = Aggregation to define the start date for the plotting
windows, the default is the first day for the estimate evapotranspiration, but can
be defined by user in the format YYYY-MM-DD.
Edate Only used when type = Aggregation to define the end date for the plotting
windows, the default is the last day for the estimate evapotranspiration, but can
be defined by user in the format YYYY-MM-DD.

Value

If argument type is Aggregation, three plots are displayed in the following order (the next one
appears after pressing enter):
1) Daily evapotranspiration estimates;
2) Monthly evapotranspiration estimates aggregated from daily estimates;
3) Annual evapotranspiration estimates aggregated from daily estimates.

If argument type is Average, two plots are displayed in the following order
1) Monthly averaged daily estimations of evapotranspiration;
2) Annually averaged daily estiamtions of evapotranspriation.

Author(s)

Danlu Guo

See Also

ETComparison

Examples
# Use processed existing data set and constants from kent Town, Adelaide
data("processeddata")
data("constants")

# Call ET.Penman under the generic function ET

results <- ET.Penman(processeddata, constants, ts="daily", solar="sunshine hours",
wind="yes", windfunction_ver = "1948", alpha = 0.08, z0 = 0.001, save.csv="no")

# Read evaporation data

data("E_OBS")
OBS <- ReadOBSEvaporation(E_OBS, processeddata)

# Plot the aggregation of estimated Penman open-water evaporation with observed evaporation
ETPlot(results, type = "Aggregation", OBS, OBSplot = TRUE, Sdate = "2001-05-01",
Edate = "2004-05-01")
E_OBS 67

E_OBS Observed Class-A Pan Evaporation

Description
This data set contains the Class-A pan evaporation observed over the period between 1/3/2001 and
31/8/2004 at the Kent Town station in Adelaide, Australia.

Usage
data(E_OBS)

Format
A list containing 48 obserations of 5 variables

Source
Bureau of Meteorology, Kent Town, Adelaide, Australia

processeddata Processed Climate Data Required for Calculating Evapotranspiration

Description
This data set contains the processed climate data including the variables required for calculating
evapotranspiration in function ET over the observation period between 1/3/2001 and 31/8/2004 at
the Kent Town station in Adelaide, Australia.

Usage
data(processeddata)

Format
A list containing 11 non-empty variables:

Date.daily - date in daily time step,

Date.monthly - date in monthly time step,
J - julian days,
i - month,
ndays - days in month,
Tmax - daily maximum temperature in degree Celcius,
Tmin - daily minimum temperature in degree Celcius,
RHmax - daily maximum relative humidity in percentage,
RHmin - daily minimum relative humidity in percentage,
uz - daily wind speed in meters per second,
Rs - daily solar radiation in Megajoule per square meter.
68 ReadInputs

Source
Bureau of Meteorology, Kent Town, Adelaide, Australia

ReadInputs ReadInputs raw date and climate data

Description
Load raw date and climate data, perform pre-processing, check for missing and error entries and
then compile data list of daily time step.

Usage
ReadInputs(varnames, climatedata, constants, stopmissing, timestep = "daily",
interp_missing_days = FALSE,
interp_missing_entries = FALSE,
interp_abnormal = FALSE,
missing_method = NULL,
abnormal_method = NULL,
message = "yes")

Arguments
varnames A character vector with length equals to the number of climate variables to be
processed. Can include any element from: Tmax, Tmin, Temp, Tdew, RHmax,
RHmin, RH, Rs, n, Cd, Precip, uz, u2, Epan, va, vs.

Each variable is detailed as below:

Tmax - daily maximum temperature in degree Celcius,
Tmin - daily minimum temperature in degree Celcius,
Temp - subdaily temperature in degree Celcius
Tdew - dew point temperature in degree Celcius, either daily or subdaily ac-
cepted,
RHmax - daily maximum relative humidity in percentage,
RHmin - daily minimum relative humidity in percentage,
RH - subdaily relative humidity in percentage,
Rs - incoming solar radiation in Megajoules per square metres per day, either
daily or subdaily accepted,
n - daily sunshine hour in hours,
Cd - daily cloud cover in oktas,
Precip - precipitation in millimitres, either daily or subdaily accepted,
u2 - wind speed measured at 2 metres from the ground surface in metres per
second, either daily or subdaily accepted,
uz - wind speed in metres per second, either daily or subdaily accepted,
Epan - daily Class-A pan evaporation in millimitres,
va - average vapour pressure in KPa, either daily or subdaily accepted,
ReadInputs 69

vs - saturated vapour pressure in KPa, either daily or subdaily accepted.

climatedata A data frame named "climatedata" containing the raw data of date and climate
variables.
The data frame must have objects named as Year, Month and Day to indicate the
date.
The climate variables to include should be consistent with varnames.
In order to determine which variables are needed for ET estimation, please see
ET for the specific data requirements for different formulations.
timestep Should be either daily or subdaily to specify the time step of raw climate data
used.
constants A list named "constants" consists of constants required for data pre-processing
which may contain the following items:
a_0, b_0, c_0, d_0.
These four constants which are constants required to calculate daily sunshine
hours from daily cloud cover (see Equation S3.10 in McMahon et al., 2012) -
if the user requires such calculation these constants must be included in "con-
stants".
The suggested values for various Australian locations are presented in Chiew
and McMahon (1991), in which the four constants are named as a0, b0, c0, d0.
stopmissing A numeric vector of length 3:
- the first value represents the maximum percentage of missing data that the user
can tolerate;
- the second value represents the maximum percentage of the duration of missing
data to the total data duaration that the user can toleratre;
- the third value represents the maximum percentage of missing days (within the
date data, as a fraction of the total number of days) that the user can tolerate.
All values should be numbers between 1 and 99.
The percentages of the number and duration of missing data in the date data and
each input variable are compared to the corresponding threshold; if any of the
threshold is exceeded the program will be terminated due to unsatisfactory data
quality.
interp_missing_days
T or F, indicating if missing days (within the date data) should be interpolated,
with a default of F which assigns NA to data at the missing days.

interp_missing_entries
T or F, indicating if missing data entries within individual climate variables
should be interpolated, with a default of F which assigns NA to the missing en-
tries.
interp_abnormal
T or F, if abnormal values within individual climate variables should be interpo-
lated, with a default of F which leaves the abnormal values unchanged.
Abnormal values are defined differently according to the input variable, as fol-
lowing:

- Tmax > 100 or < -50 degree Celcius

70 ReadInputs

- Tmin > Tmax or < -50 degree Celcius

- Temp > 100 or < -50 degree Celcius
- Tdew > 100 or < -50 degree Celcius
- RHmax > 100 or < 0 per cent
- RHmin > RHmax or < 0 per cent
- RH > 100 per cent
- Rs < 0 MJ.m^2
- n < 0 hour
- Cd < 0 Okta
- Precip < 0 mm
- uz < 0 m/s
- u2 < 0 m/s
- Epan < 0 mm
- vs < 0 KPa
- va < 0 KPa

missing_method A character string for the name of the interpolated methods chosen for filling in
missing days and missing data entries. Can be either:

monthly average - replacement with same-month average (adapted from Nara-

pusetty et al., 2009);
seasonal average - replacement with same-season average (adapted from Nara-
pusetty et al., 2009);
DoY average - replacement with same day-of-the-year average (Narapusetty et
al., 2009);
neighbouring average - interpolation between the two bounding values, which
is only suitable for time increments in which values are available at adjacent in-
crements (McMahon et al., 2013). When there is more than one consecutive
missing entry, this interpolation fails, with a warning given.

abnormal_method
A character string for the name of the interpolated methods chosen for replacing
data entries with abnormal values. Can be either:

monthly average - replacement with same-month average (adapted from Nara-

pusetty et al., 2009);
seasonal average - replacement with same-season average (adapted from Nara-
pusetty et al., 2009);
DoY average - replacement with same day-of-the-year average (Narapusetty et
al., 2009);
neighbouring average - interpolation between the two bounding values, which
is only suitable for time increments in which non-abnormal values are available
at adjacent increments (McMahon et al., 2013). When there is more than one
consecutive abnormal entry, this interpolation fails, with a warning given.

message "yes" or "no" indicating whether checking messages should be printed on screen.
ReadInputs 71

Value
This function returns a list with all components of class zoo which have been processed from the
raw data, including:

Date.daily A zoo object containing the date in daily step in the format of yyyy-mm-dd.
Date.monthly A zoo object containing the date in daily step in the format of mmm-yyyy.
J A zoo object containing the Julian Day for every day during the period that the
data spans.
i A zoo object containing the month number for every day during the period that
the data spans.
ndays A zoo object containing the number of days for every month during the period
that the data spans.
Tmax A zoo object containing the daily maximum temperatures in degree Celcius.
Tmin A zoo object containing the daily minimum temperatures in degree Celcius.
u2 A zoo object containing the daily wind speed at 2m from the ground in m/s.
uz A zoo object containing the daily wind speed measured at the height of wind
instrument in m/s.
Rs A zoo object containing the daily solar radiation in MJ/m^2/day.
n A zoo object containing the daily sunshine hours.
Cd A zoo object containing the daily cloud cover in oktas.
Precip A zoo object containing the daily precipitation in mm.
Epan A zoo object containing the daily Class-A pan evaporation in mm.
RHmax A zoo object containing the daily maximum relative humidity in percentage.
RHmin A zoo object containing the daily minimum relative humidity in percentage.
Tdew A zoo object containing the average daily dew temperatures in degree Celcius.

Note that the components might have value of NULL when the corresponding input variable cannot
be found in the raw data (i.e. "climatedata").

Author(s)
Danlu Guo

References
McMahon, T., Peel, M., Lowe, L., Srikanthan, R. & McVicar, T. 2012. Estimating actual, potential,
reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis.
Hydrology and Earth System Sciences Discussions, 9, 11829-11910.
Chiew, F. H. & McMahon, T. A. 1991. The applicability of Morton’s and Penman’s evapotranspi-
ration estimates in rainfall-runoff modeling1. JAWRA Journal of the American Water Resources
Association, 27, 611-620.
Narapusetty, B., DelSole, T.Tippett, M.K. 2009, Optimal Estimation of the Climatological Mean.
Journal of Climate, vol. 22, no. 18, pp. 4845-4859.
72 ReadOBSEvaporations

See Also
ET,climatedata,data

Examples
# ReadInputs climate data
data("climatedata")
data("constants")
data <- ReadInputs(varnames = c("Temp","Tdew","n","RH","uz"),
climatedata,
constants,
stopmissing=c(10,10,3),
timestep = "subdaily",
interp_missing_days = FALSE,
interp_missing_entries = FALSE,
interp_abnormal = FALSE,
missing_method = NULL,
abnormal_method = NULL)

ReadOBSEvaporations Read Raw Data of Observed Evaporation from file

Description
Load raw date and evaporation data and then compile data list of daily time step.

Usage
ReadOBSEvaporation(E_OBS, data)

Arguments
E_OBS A list of evaporation data named E_OBS which must contain the following columns:
Year, Month, Day as the date and,
EVAP.Obs as the observed evaporation in mm.
The observations can be of daily and monthly time steps and must match with
the corresponding dates recorded.
data A list of data named data which contains data of climate variables over the same
period as the evaporation data

Value
This function returns a list with all components of class zoo which have been processed from the
raw data, including:

Date.OBS A zoo object containing the date data with time step consistent with the raw
evaporation data in E_OBS.
ReadOBSEvaporations 73

E_obs.Daily A zoo object containing the daily evaporation data.

E_obs.Monthly A zoo object containing the monthly aggregaated observed evaporation in mm.
E_obs.Annual A zoo object containing the annually aggregated observed evaporation in mm.
E_obs.MonthlyAve
A zoo object containing the monthly averaged daily evaporation from observa-
tion in mm/day.
E_obs.AnnualAve
A zoo object containing the annually average daily evaporation from observation
in mm/day.
Note that the components might have value of NULL when the corresponding raw data cannot be
found in E_OBS.

Author(s)
Danlu Guo

Examples
# Get the time period from "data"
# Use processed existing data set from kent Town, Adelaide
data("processeddata")
data("constants")

# Reading obsevations of evaporation within specified time period

data("E_OBS")
OBS <- ReadOBSEvaporation(E_OBS, processeddata)
Index

∗ ASCE ET.Penman, 42
ET.PenmanMonteith, 46 ∗ Priestley-Taylor
∗ Abtew ET.PriestleyTaylor, 52
ET.Abtew, 8 ∗ ReadInputs
∗ BlaneyCriddle ReadInputs, 68
ET.BlaneyCriddle, 10 ∗ Reading
∗ Brutsaert-Strickler ReadOBSEvaporations, 72
ET.BrutsaertStrickler, 13 ∗ Reference crop evapotranspiration
∗ Chapman ET.PenmanMonteith, 46
ET.ChapmanAustralian, 15 ∗ Romanenko
∗ Class-A pan evaporation ET.Romanenko, 54
ET.PenPan, 49 ∗ Szilagyi-Jozsa
∗ FAO-56 ET.SzilagyiJozsa, 56
ET.PenmanMonteith, 46 ∗ Turc
∗ Granger-Gray ET.Turc, 59
ET.GrangerGray, 18 ∗ actual areal evapotranspiration
∗ Hamon ET.BrutsaertStrickler, 13
ET.Hamon, 21 ET.MortonCRAE, 36
∗ Hargreaves-Samani ∗ actual evapotranspiration
ET.HargreavesSamani, 23 ET.Abtew, 8
∗ Jensen-Haise ET.Linacre, 27
ET.JensenHaise, 25 ET.SzilagyiJozsa, 56
∗ Linacre ∗ climate
ET.Linacre, 27 ETComparison, 62
∗ Makkink ETForcings, 64
ET.Makkink, 29 ∗ data pre-processing
∗ Matt-Shuttleworth ReadInputs, 68
ET.MattShuttleworth, 31 ∗ datasets
∗ McGuinness-Bordne climatedata, 2
ET.McGuinnessBordne, 34 constants, 3
∗ MortonCRAE defaultconstants, 5
ET.MortonCRAE, 36 E_OBS, 67
∗ MortonCRWE processeddata, 67
ET.MortonCRWE, 39 ∗ evapotranspiration
∗ PenPan ET, 6
ET.PenPan, 49 ET.Abtew, 8
∗ Penman-Monteith ET.BlaneyCriddle, 10
ET.PenmanMonteith, 46 ET.BrutsaertStrickler, 13
∗ Penman ET.ChapmanAustralian, 15

74
INDEX 75

ET.GrangerGray, 18 ∗ reference crop evapotranspiration

ET.Hamon, 21 ET.BlaneyCriddle, 10
ET.HargreavesSamani, 23 ET.HargreavesSamani, 23
ET.JensenHaise, 25 ET.Makkink, 29
ET.Linacre, 27 ET.MattShuttleworth, 31
ET.MattShuttleworth, 31 ET.Turc, 59
ET.McGuinnessBordne, 34 ∗ shallow lake
ET.MortonCRAE, 36 ET.MortonCRWE, 39
ET.Penman, 42 ∗ wet-environment areal evapotranspiration
ET.PenmanMonteith, 46 ET.MortonCRAE, 36
ET.PenPan, 49
ET.PriestleyTaylor, 52 climatedata, 2, 72
ET.Romanenko, 54 constants, 3, 6, 10, 12, 15, 18, 20, 24, 27, 28,
ET.SzilagyiJozsa, 56 31, 33, 35, 39, 42, 45, 48, 51, 54, 59,
ET.Turc, 59 61
ETComparison, 62
data, 72
ETForcings, 64
defaultconstants, 5, 5, 10, 12, 15, 18, 20,
ETPlot, 65
24, 27, 28, 31, 33, 35, 39, 42, 45, 48,
ReadInputs, 68
51, 54, 59, 61
ReadOBSEvaporations, 72
∗ forcing E_OBS, 67
ETComparison, 62 ET, 2, 3, 5, 6, 10, 12, 15, 18, 20, 22, 24, 27, 28,
ETForcings, 64 31, 33, 35, 45, 48, 51, 54, 55, 59, 61,
∗ observation 67, 69, 72
ReadOBSEvaporations, 72 ET.Abtew, 8
∗ open-water evaporation ET.BlaneyCriddle, 10
ET, 6 ET.BrutsaertStrickler, 13
ET.GrangerGray, 18 ET.ChapmanAustralian, 15
ET.MortonCRWE, 39 ET.GrangerGray, 18
ET.Penman, 42 ET.Hamon, 21
∗ plot ET.HargreavesSamani, 8, 23
ETComparison, 62 ET.JensenHaise, 25
ETForcings, 64 ET.Linacre, 27
ETPlot, 65 ET.Makkink, 7, 29
∗ potential evaporation ET.MattShuttleworth, 31
ET.PriestleyTaylor, 52 ET.McGuinnessBordne, 34
∗ potential evapotranspiration ET.MortonCRAE, 36
ET, 6 ET.MortonCRWE, 39, 39, 42
ET.ChapmanAustralian, 15 ET.Penman, 7, 20, 42, 59
ET.GrangerGray, 18 ET.PenmanMonteith, 7, 46
ET.Hamon, 21 ET.PenPan, 18, 49
ET.JensenHaise, 25 ET.PriestleyTaylor, 7, 52
ET.McGuinnessBordne, 34 ET.Romanenko, 54
ET.MortonCRAE, 36 ET.SzilagyiJozsa, 56
ET.MortonCRWE, 39 ET.Turc, 59
ET.Penman, 42 ETComparison, 62, 66
ET.PenPan, 49 ETForcings, 64
ET.Romanenko, 54 ETPlot, 63, 65, 65
76 INDEX

processeddata, 10, 12, 15, 18, 20, 22, 24, 27,

28, 31, 33, 35, 39, 42, 45, 48, 51, 54,
55, 59, 61, 67

ReadInputs, 68
ReadOBSEvaporation
(ReadOBSEvaporations), 72
ReadOBSEvaporations, 72