NAME
i.eb.netrad - Net radiation approximation (Bastiaanssen, 1995).
KEYWORDS
imagery, energy balance, net radiation, SEBAL
SYNOPSIS
i.eb.netrad
i.eb.netrad help
i.eb.netrad albedo=name ndvi=name temperature=name localutctime=name temperaturedifference2m=name emissivity=name transmissivitysingleway=name dayofyear=name sunzenithangle=name output=name [--overwrite] [--verbose] [--quiet]
Flags:
- --overwrite
- Allow output files to overwrite existing files
- --verbose
- Verbose module output
- --quiet
- Quiet module output
Parameters:
- albedo=name [required]
- Name of the Albedo map [0.0;1.0]
- Default: albedo
- ndvi=name [required]
- Name of the ndvi map [-1.0;+1.0]
- Default: ndvi
- temperature=name [required]
- Name of the Surface temperature map [degree Kelvin]
- Default: tempk
- localutctime=name [required]
- Name of the map of local UTC time of satellite overpass [hh.hhh]
- Default: time
- temperaturedifference2m=name [required]
- Name of the difference of temperature from surface skin to about 2 m height [K]
- Default: dtair
- emissivity=name [required]
- Name of the emissivity map [-]
- Default: emissivity
- transmissivitysingleway=name [required]
- Name of the single-way atmospheric transmissivitymap [-]
- Default: tsw
- dayofyear=name [required]
- Name of the Day Of Year (DOY) map [-]
- Default: doy
- sunzenithangle=name [required]
- Name of the sun zenith angle map [degrees]
- Default: sunzangle
- output=name [required]
- Name of the output net radiation layer
DESCRIPTION
i.eb.netrad calculates the net radiation at the time of satellite
overpass, the way it is in the SEBAL model of Bastiaanssen (1995).
It takes input of Albedo, NDVI, Surface Skin temperature, time of satellite
overpass, surface emissivity, difference of temperature from surface skin and
about 2 m height (dT), instantaneous satellite overpass single-way atmospheric
transmissivity (tsw), Day of Year (DOY), and sun zenith angle.
NOTES
In the old methods, dT was taken as flat images (dT=5.0), if you don't have a dT
map from ground data, you would want to try something in this line, this is to
calculate atmospherical energy balance. In the same way, a standard tsw is used
in those equations. Refer to r_net.c for that and for other non-used equations,
but stored in there for further research convenience.
TODO
Add more explanations.
SEE ALSO
i.eb.soilheatflux
i.eb.h_SEBAL01
i.albedo
AUTHORS
Yann Chemin, International Rice Research Institute, The Philippines
Last changed: $Date: 2011-11-08 13:24:20 -0800 (Tue, 08 Nov 2011) $
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