i.evapo.potrad
Potential evapotranspiration, radiative method after Bastiaanssen (1995)
i.evapo.potrad [-rdb] albedo=name temperature=name latitude=name dayofyear=name transmissivitysingleway=name waterdensity=float [slope=name] [aspect=name] [atmosphericemissivity=float] [airtemperature=name] [surfaceemissivity=name] output=name [rnetd=name] [--overwrite] [--verbose] [--quiet] [--qq] [--ui]
Example:
i.evapo.potrad albedo=name temperature=name latitude=name dayofyear=name transmissivitysingleway=name waterdensity=1005.0 output=name
grass.script.run_command("i.evapo.potrad", albedo, temperature, latitude, dayofyear, transmissivitysingleway, waterdensity=1005.0, slope=None, aspect=None, atmosphericemissivity=0.845, airtemperature=None, surfaceemissivity=None, output, rnetd=None, flags=None, overwrite=False, verbose=False, quiet=False, superquiet=False)
Example:
gs.run_command("i.evapo.potrad", albedo="name", temperature="name", latitude="name", dayofyear="name", transmissivitysingleway="name", waterdensity=1005.0, output="name")
Parameters
albedo=name [required]
Name of the Albedo layer [0.0-1.0]
temperature=name [required]
Name of the temperature layer [Degree Kelvin]
latitude=name [required]
Name of the degree latitude layer [dd.ddd]
dayofyear=name [required]
Name of the Day of Year layer [0.0-366.0]
transmissivitysingleway=name [required]
Name of the single-way transmissivity layer [0.05-1.0], defaults to 1.0 if no input file
waterdensity=float [required]
Value of the density of fresh water ~[1000-1020]
Default: 1005.0
slope=name
Name of the Slope layer ~[0-90]
aspect=name
Name of the Aspect layer ~[0-360]
atmosphericemissivity=float
Value of the apparent atmospheric emissivity (Bandara, 1998 used 0.845 for Sri Lanka)
Default: 0.845
airtemperature=name
Name of the Air Temperature layer [Kelvin], use with -b
surfaceemissivity=name
Name of the Surface Emissivity layer [-], use with -b
output=name [required]
OUTPUT: Name of the Potential ET layer
rnetd=name
OUTPUT: Name of the Diurnal Net Radiation layer
-r
Output Diurnal Net Radiation (for i.eb.eta)
-d
Slope/Aspect correction
-b
Net Radiation Bandara (1998), generic Longwave calculation, need apparent atmospheric emissivity, Air temperature and surface emissivity inputs
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--qq
Very quiet module output
--ui
Force launching GUI dialog
albedo : str, required
Name of the Albedo layer [0.0-1.0]
Used as: input, raster, name
temperature : str, required
Name of the temperature layer [Degree Kelvin]
Used as: input, raster, name
latitude : str, required
Name of the degree latitude layer [dd.ddd]
Used as: input, raster, name
dayofyear : str, required
Name of the Day of Year layer [0.0-366.0]
Used as: input, raster, name
transmissivitysingleway : str, required
Name of the single-way transmissivity layer [0.05-1.0], defaults to 1.0 if no input file
Used as: input, raster, name
waterdensity : float, required
Value of the density of fresh water ~[1000-1020]
Used as: 1005.0
Default: 1005.0
slope : str, optional
Name of the Slope layer ~[0-90]
Used as: input, raster, name
aspect : str, optional
Name of the Aspect layer ~[0-360]
Used as: input, raster, name
atmosphericemissivity : float, optional
Value of the apparent atmospheric emissivity (Bandara, 1998 used 0.845 for Sri Lanka)
Used as: 1005.0
Default: 0.845
airtemperature : str, optional
Name of the Air Temperature layer [Kelvin], use with -b
Used as: input, raster, name
surfaceemissivity : str, optional
Name of the Surface Emissivity layer [-], use with -b
Used as: input, raster, name
output : str, required
OUTPUT: Name of the Potential ET layer
Used as: output, raster, name
rnetd : str, optional
OUTPUT: Name of the Diurnal Net Radiation layer
Used as: output, raster, name
flags : str, optional
Allowed values: r, d, b
r
Output Diurnal Net Radiation (for i.eb.eta)
d
Slope/Aspect correction
b
Net Radiation Bandara (1998), generic Longwave calculation, need apparent atmospheric emissivity, Air temperature and surface emissivity inputs
overwrite: bool, optional
Allow output files to overwrite existing files
Default: False
verbose: bool, optional
Verbose module output
Default: False
quiet: bool, optional
Quiet module output
Default: False
superquiet: bool, optional
Very quiet module output
Default: False
DESCRIPTION
i.evapo.potrad calculates the diurnal potential evapotranspiration after Bastiaanssen (1995). This is converting all Net radiation from the diurnal period into ET. It takes input maps of Albedo, surface skin temperature, latitude, day of year, single-way transmissivity and takes input value of the density of fresh water. The "-r" flag permits output map of Diurnal net radiation to use in r.eb.eta. The "-b" flag permits a generic longwave balance calculation from surface emissivity, Air Temperature and a value of apparent atmospheric emissivity. The "-d" flag is a slope/aspect correction, not really tested, reports and tests are most welcome.
NOTES
TODO
Slope/aspect correction to be screened and tested by somebody in the known.
SEE ALSO
REFERENCES
- Bastiaanssen, W.G.M., 1995. Regionalization of surface flux densities and moisture indicators in composite terrain; a remote sensing approach under clear skies in mediterranean climates. PhD thesis, Wageningen Agricultural Univ., The Netherland, 271 pp. (PDF)
- Chemin, Y., 2012. A Distributed Benchmarking Framework for Actual ET Models, in: Irmak, A. (Ed.), Evapotranspiration - Remote Sensing and Modeling. InTech. (PDF, DOI: 10.5772/23571)
AUTHOR
Yann Chemin, International Rice Research Institute, The Philippines
SOURCE CODE
Available at: i.evapo.potrad source code
(history)
Latest change: Friday Feb 21 10:10:05 2025 in commit 7d78fe3