NAME
i.evapo.potrad - Potential evapotranspiration, radiative method after Bastiaanssen (1995)KEYWORDS
Potential ET, evapotranspirationSYNOPSIS
i.evapo.potrad
i.evapo.potrad --helpi.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] [--help] [--verbose] [--quiet] [--ui]
Flags:
- -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
- --ui
- Force launching GUI dialog
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
Table of contents
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
r.suni.albedo
i.eb.eta
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)
AUTHOR
Yann Chemin, International Rice Research Institute, The PhilippinesSOURCE CODE
Available at: i.evapo.potrad source code (history)
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