i.eb.netrad(1grass) GRASS GIS User's Manual i.eb.netrad(1grass)
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 transmissivity_single-
way=name dayofyear=name sunzenithangle=name output=name [--overwrite]
[--help] [--verbose] [--quiet] [--ui]
Flags:
--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 albedo raster map [0.0;1.0]
ndvi=name [required]
Name of NDVI raster map [-1.0;+1.0]
temperature=name [required]
Name of surface temperature raster map [K]
localutctime=name [required]
Name of time of satellite overpass raster map [local time in UTC]
temperaturedifference2m=name [required]
Name of the difference map of temperature from surface skin to
about 2 m height [K]
emissivity=name [required]
Name of the emissivity map [-]
transmissivity_singleway=name [required]
Name of the single-way atmospheric transmissivitymap [-]
dayofyear=name [required]
Name of the Day Of Year (DOY) map [-]
sunzenithangle=name [required]
Name of the sun zenith angle map [degrees]
output=name [required]
Name of the output net radiation layer
DESCRIPTION
i.eb.netrad calculates the net radiation at the time of satellite over-
pass, the way it is in the SEBAL model of Bastiaanssen (1995). It
takes input of Albedo, NDVI, Surface Skin temperature, time of satel-
lite overpass, surface emissivity, difference of temperature from sur-
face 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.hsebal01, i.albedo
REFERENCES
• Bastiaanssen, W.G.M., 1995. Regionalization of surface flux
densities and moisture indicators in composite terrain; a re-
mote sensing approach under clear skies in mediterranean cli-
mates. PhD thesis, Wageningen Agricultural Univ., The Nether-
land, 271 pp. (PDF)
• Chemin, Y., 2012. A Distributed Benchmarking Framework for Ac-
tual ET Models, in: Irmak, A. (Ed.), Evapotranspiration - Re-
mote Sensing and Modeling. InTech. (PDF)
AUTHOR
Yann Chemin, International Rice Research Institute, The Philippines
SOURCE CODE
Available at: i.eb.netrad source code (history)
Accessed: unknown
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