i.eb.soilheatflux

Soil heat flux approximation (Bastiaanssen, 1995).

Command linePython (grass.script)

i.eb.soilheatflux [-r] albedo=name ndvi=name temperature=name netradiation=name localutctime=name output=name [--overwrite] [--verbose] [--quiet] [--qq] [--ui]

Example:

i.eb.soilheatflux albedo=name ndvi=name temperature=name netradiation=name localutctime=name output=name

grass.script.run_command("i.eb.soilheatflux", albedo, ndvi, temperature, netradiation, localutctime, output, flags=None, overwrite=False, verbose=False, quiet=False, superquiet=False)

Example:

gs.run_command("i.eb.soilheatflux", albedo="name", ndvi="name", temperature="name", netradiation="name", localutctime="name", output="name")

Parameters

Command linePython (grass.script)

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
-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
--qq
    Very quiet module output
--ui
    Force launching GUI dialog

albedo : str, required
    Name of albedo raster map [0.0;1.0]
    Used as: input, raster, name
ndvi : str, required
    Name of NDVI raster map [-1.0;+1.0]
    Used as: input, raster, name
temperature : str, required
    Name of Surface temperature raster map [K]
    Used as: input, raster, name
netradiation : str, required
    Name of Net Radiation raster map [W/m2]
    Used as: input, raster, name
localutctime : str, required
    Name of time of satellite overpass raster map [local time in UTC]
    Used as: input, raster, name
output : str, required
    Name for output raster map
    Used as: output, raster, name
flags : str, optional
    Allowed values: r
    r
        HAPEX-Sahel empirical correction (Roerink, 1995)
overwrite: bool, optional
    Allow output files to overwrite existing files
    Default: False
verbose: bool, optional
    Verbose module output
    Default: False
quiet: bool, optional
    Quiet module output
    Default: False
superquiet: bool, optional
    Very quiet module output
    Default: False

DESCRIPTION

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"

REFERENCES

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)

AUTHOR

Yann Chemin, Asian Institute of Technology, Thailand

SOURCE CODE

Available at: i.eb.soilheatflux source code (history)
Latest change: Friday Feb 07 19:16:09 2025 in commit a82a39f