i.eb.soilheatflux(1grass) GRASS GIS User's Manual i.eb.soilheatflux(1grass)
NAME
i.eb.soilheatflux - Soil heat flux approximation (Bastiaanssen, 1995).
KEYWORDS
imagery, energy balance, soil heat flux, SEBAL
SYNOPSIS
i.eb.soilheatflux
i.eb.soilheatflux --help
i.eb.soilheatflux [-r] albedo=name ndvi=name temperature=name netradia-
tion=name localutctime=name output=name [--overwrite] [--help]
[--verbose] [--quiet] [--ui]
Flags:
-r
HAPEX-Sahel empirical correction (Roerink, 1995)
--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]
netradiation=name [required]
Name of Net Radiation raster map [W/m2]
localutctime=name [required]
Name of time of satellite overpass raster map [local time in UTC]
output=name [required]
Name for output raster map
DESCRIPTION
i.eb.soilheatflux calculates the soil heat flux approximation (g0) af-
ter Bastiaanssen (1995). The main reference for implementation is
Alexandridis, 2009. It takes input of Albedo, NDVI, Surface Skin tem-
perature, Net Radiation (see r.sun), time of satellite overpass, and a
flag for the Roerink empirical modification from the HAPEX-Sahel exper-
iment. The "time of satellite overpass" map can be obtained as fol-
lows:
• MODIS: a related sub dataset is included in each HDF file, and
simply to be imported as a raster map;
• Landsat: to be generated as map from the overpass time stored
in the metadata file (given in Greenwich Mean Time - GMT), see
below.
For Landsat, the overpass map can be computed by using a two-step
method:
# 1) extract the overpass time in GMT from metadata file
i.landsat.toar -p input=dummy output=dummy2 \
metfile=LC81250452013338LGN00_MTL.txt lsatmet=time
# ... in this example approx. 03:12am GMT
# 2) create map for computational region of Landsat scene
g.region rast=LC81250452013338LGN00_B4 -p
r.mapcalc "overpasstime = 3.211328"
SEE ALSO
r.sun, i.albedo, i.emissivity, i.eb.hsebal01, i.eb.evapfr i.land-
sat.toar
REFERENCES
Bastiaanssen, W.G.M., 1995. Estimation of Land surface parameters by
remote sensing under clear-sky conditions. PhD thesis, Wageningen Uni-
versity, Wageningen, The Netherlands. (PDF)
Chemin Y., Alexandridis T.A., 2001. Improving spatial resolution of ET
seasonal for irrigated rice in Zhanghe, China. Asian Journal of Geoin-
formatics. 5(1):3-11,2004.
Alexandridis T.K., Cherif I., Chemin Y., Silleos N.G., Stavrinos E.,
Zalidis G.C. Integrated methodology for estimating water use in
Mediterranean agricultural areas. Remote Sensing. 2009, 1, 445-465.
(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, Asian Institute of Technology, Thailand
SOURCE CODE
Available at: i.eb.soilheatflux source code (history)
Accessed: unknown
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