xenial (1) i.eb.netrad.1grass.gz

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_singleway=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 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.hsebal01, i.albedo

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 Philippines

       Last changed: $Date: 2014-12-09 18:31:29 +0100 (Tue, 09 Dec 2014) $

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