.TH i.eb.soilheatflux 1grass "" "GRASS 7.2.0" "Grass User's Manual"
.SH NAME
\fI\fBi.eb.soilheatflux\fR\fR  \- Soil heat flux approximation (Bastiaanssen, 1995).
.SH KEYWORDS
imagery, energy balance, soil heat flux, SEBAL
.SH SYNOPSIS
\fBi.eb.soilheatflux\fR
.br
\fBi.eb.soilheatflux \-\-help\fR
.br
\fBi.eb.soilheatflux\fR [\-\fBr\fR] \fBalbedo\fR=\fIname\fR \fBndvi\fR=\fIname\fR \fBtemperature\fR=\fIname\fR \fBnetradiation\fR=\fIname\fR \fBlocalutctime\fR=\fIname\fR \fBoutput\fR=\fIname\fR  [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-r\fR" 4m
.br
HAPEX\-Sahel empirical correction (Roerink, 1995)
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBalbedo\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of albedo raster map [0.0;1.0]
.IP "\fBndvi\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of NDVI raster map [\-1.0;+1.0]
.IP "\fBtemperature\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of Surface temperature raster map [K]
.IP "\fBnetradiation\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of Net Radiation raster map [W/m2]
.IP "\fBlocalutctime\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of time of satellite overpass raster map [local time in UTC]
.IP "\fBoutput\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name for output raster map
.SH DESCRIPTION
\fIi.eb.soilheatflux\fR 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
\fIr.sun\fR), time of satellite overpass, and a flag for the Roerink empirical modification from the HAPEX\-Sahel experiment.
The \(dqtime of satellite overpass\(dq map can be obtained as follows:
.RS 4n
.IP \(bu 4n
MODIS: a related sub dataset is included in each HDF file, and simply
to be imported as a raster map;
.IP \(bu 4n
Landsat: to be generated as map from the overpass time stored in
the metadata file (given in Greenwich Mean Time \- GMT), see below.
.RE
For Landsat, the overpass map can be computed by using a two\-step method:
.br
.nf
\fC
# 1) extract the overpass time in GMT from metadata file
i.landsat.toar \-p input=dummy output=dummy2 \(rs
   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 \(dqoverpasstime = 3.211328\(dq
\fR
.fi
.SH SEE ALSO
\fI
r.sun,
i.albedo,
i.emissivity,
i.eb.hsebal01,
i.eb.evapfr
i.landsat.toar
\fR
.SH REFERENCES
.PP
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)
.PP
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.
.PP
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)
.PP
Chemin, Y., 2012.
A Distributed Benchmarking Framework for Actual ET Models,
in: Irmak, A. (Ed.), Evapotranspiration \- Remote Sensing and Modeling. InTech.
(PDF)
.SH AUTHOR
Yann Chemin, Asian Institute of Technology, Thailand
.br
.PP
\fILast changed: $Date: 2015\-02\-27 12:03:54 +0100 (Fri, 27 Feb 2015) $\fR
.SH SOURCE CODE
.PP
Available at: i.eb.soilheatflux source code (history)
.PP
Main index |
Imagery index |
Topics index |
Keywords index |
Graphical index |
Full index
.PP
© 2003\-2016
GRASS Development Team,
GRASS GIS 7.2.0 Reference Manual