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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 netradiation=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
i.eb.soilheatflux calculates the soil heat flux approximation (g0)
after Bastiaanssen (1995). The main reference for implementation is Alexandridis, 2009.
It takes input of Albedo, NDVI, Surface Skin temperature, Net Radiation (see
r.sun), time of satellite overpass, and a flag for the Roerink empirical modification from the HAPEX-Sahel experiment.
The "time of satellite overpass" map can be obtained as follows:
- 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"
Bastiaanssen, W.G.M., 1995.
Estimation of Land surface parameters by remote sensing under clear-sky
conditions. PhD thesis, Wageningen University, 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 Geoinformatics. 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)
r.sun,
i.albedo,
i.emissivity,
i.eb.hsebal01,
i.eb.evapfr
i.landsat.toar
Yann Chemin, Asian Institute of Technology, Thailand
SOURCE CODE
Available at:
i.eb.soilheatflux source code
(history)
Latest change: Thursday Jan 26 14:10:26 2023 in commit: cdd84c130cea04b204479e2efdc75c742efc4843
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GRASS Development Team,
GRASS GIS 8.3.3dev Reference Manual