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NAME

i.eb.netrad - net radiation approximation (Bastiaanssen, 1995)

KEYWORDS

net radiation, energy balance, SEBAL, energy balance, 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
Name of the Albedo map [0.0;1.0]
Default: albedo
ndvi=name
Name of the ndvi map [-1.0;+1.0]
Default: ndvi
temperature=name
Name of the Surface temperature map [degree Kelvin]
Default: tempk
localutctime=name
Name of the map of local UTC time of satellite overpass [hh.hhh]
Default: time
temperaturedifference2m=name
Name of the difference of temperature from surface skin to about 2 m height [K]
Default: dtair
emissivity=name
Name of the emissivity map [-]
Default: emissivity
transmissivitysingleway=name
Name of the single-way atmospheric transmissivitymap [-]
Default: tsw
dayofyear=name
Name of the Day Of Year (DOY) map [-]
Default: doy
sunzenithangle=name
Name of the sun zenith angle map [degrees]
Default: sunzangle
output=name
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

SEE ALSO

i.eb.g0
i.albedo

AUTHORS

Yann Chemin, International Rice Research Institute, The Philippines

Last changed: $Date: 2011-01-11 16:45:35 -0800 (Tue, 11 Jan 2011) $


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