Description Usage Arguments Details Author(s) Examples
View source: R/Evapotranspiration.R
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.
1 |
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 |
... |
Arguments to be passed to methods which differs for each evapotranspiration formulations, see specific formulations for 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 following 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
);
- If all variables of Tmax/Tmin are available:
Hargreaves-Samani (ET.HargreavesSamani
).
Danlu Guo
1 2 3 4 5 6 7 8 9 | # 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")
|
Loading required package: zoo
Attaching package: ‘zoo’
The following objects are masked from ‘package:base’:
as.Date, as.Date.numeric
No ET model specified and no valid evaporative surface specified, choose the Penman model for open-water evaporation according to the data availability
Penman Open-water Evaporation
Evaporative surface: water, albedo = 0.08 ; roughness height = 0.001 m
Sunshine hour data have been used for calculating incoming solar radiation
Wind data have been used for calculating the Penman evaporation. Penman 1948 wind function has been used.
Timestep: daily
Units: mm
Time duration: 2001-03-01 to 2004-08-31
Basic stats
Mean: 4.86
Max: 12.78
Min: 1.03
No ET model specified, choose the Penman-Monteith model according to the data availability
Penman-Monteith FAO56 Reference Crop ET
Evaporative surface: FAO-56 hypothetical short grass, albedo = 0.23 ; surface resistance = 70 sm^-1; crop height = 0.12 m; roughness height = 0.02 m
Sunshine hour data have been used for calculating incoming solar radiation
Wind data have been used for calculating the reference crop evapotranspiration
Timestep: daily
Units: mm
Time duration: 2001-03-01 to 2004-08-31
1280 ET estimates obtained
Basic stats
Mean: 3.56
Max: 11.05
Min: 0.66
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