1i.eb.soilheatflux(1) GRASS GIS User's Manual i.eb.soilheatflux(1)
2
6 i.eb.soilheatflux - Soil heat flux approximation (Bastiaanssen, 1995).
7
9 imagery, energy balance, soil heat flux, SEBAL
10
12 i.eb.soilheatflux
13 i.eb.soilheatflux --help
14 i.eb.soilheatflux [-r] albedo=name ndvi=name temperature=name netradia‐
15 tion=name localutctime=name output=name [--overwrite] [--help]
16 [--verbose] [--quiet] [--ui]
17 Flags:
19 -r
20 HAPEX-Sahel empirical correction (Roerink, 1995)
21 --overwrite
23 Allow output files to overwrite existing files
24 --help
26 Print usage summary
27 --verbose
29 Verbose module output
30 --quiet
32 Quiet module output
33 --ui
35 Force launching GUI dialog
36 Parameters:
38 albedo=name [required]
39 Name of albedo raster map [0.0;1.0]
40 ndvi=name [required]
42 Name of NDVI raster map [-1.0;+1.0]
43 temperature=name [required]
45 Name of Surface temperature raster map [K]
46 netradiation=name [required]
48 Name of Net Radiation raster map [W/m2]
49 localutctime=name [required]
51 Name of time of satellite overpass raster map [local time in UTC]
52 output=name [required]
54 Name for output raster map
55
57 i.eb.soilheatflux calculates the soil heat flux approximation (g0) af‐
58 ter Bastiaanssen (1995). The main reference for implementation is
59 Alexandridis, 2009. It takes input of Albedo, NDVI, Surface Skin tem‐
60 perature, Net Radiation (see r.sun), time of satellite overpass, and a
61 flag for the Roerink empirical modification from the HAPEX-Sahel exper‐
62 iment. The "time of satellite overpass" map can be obtained as fol‐
63 lows:
64 • MODIS: a related sub dataset is included in each HDF file, and
66 simply to be imported as a raster map;
67 • Landsat: to be generated as map from the overpass time stored
69 in the metadata file (given in Greenwich Mean Time - GMT), see
70 below.
71 For Landsat, the overpass map can be computed by using a two-step
72 method:
73 # 1) extract the overpass time in GMT from metadata file
74 i.landsat.toar -p input=dummy output=dummy2 \
75 metfile=LC81250452013338LGN00_MTL.txt lsatmet=time
76 # ... in this example approx. 03:12am GMT
77 # 2) create map for computational region of Landsat scene
78 g.region rast=LC81250452013338LGN00_B4 -p
79 r.mapcalc "overpasstime = 3.211328"
80
82 Bastiaanssen, W.G.M., 1995. Estimation of Land surface parameters by
83 remote sensing under clear-sky conditions. PhD thesis, Wageningen Uni‐
84 versity, Wageningen, The Netherlands. (PDF)
85 Chemin Y., Alexandridis T.A., 2001. Improving spatial resolution of ET
87 seasonal for irrigated rice in Zhanghe, China. Asian Journal of Geoin‐
88 formatics. 5(1):3-11,2004.
89 Alexandridis T.K., Cherif I., Chemin Y., Silleos N.G., Stavrinos E.,
91 Zalidis G.C. Integrated methodology for estimating water use in
92 Mediterranean agricultural areas. Remote Sensing. 2009, 1, 445-465.
93 (PDF)
94 Chemin, Y., 2012. A Distributed Benchmarking Framework for Actual ET
96 Models, in: Irmak, A. (Ed.), Evapotranspiration - Remote Sensing and
97 Modeling. InTech. (PDF)
98
100 r.sun, i.albedo, i.emissivity, i.eb.hsebal01, i.eb.evapfr i.land‐
101 sat.toar
102
104 Yann Chemin, Asian Institute of Technology, Thailand
105
107 Available at: i.eb.soilheatflux source code (history)
108 Accessed: Mon Jun 20 16:47:27 2022
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113 © 2003-2022 GRASS Development Team, GRASS GIS 8.2.0 Reference Manual
115GRASS 8.2.0 i.eb.soilheatflux(1)