table of contents
i.eb.hsebal01(1grass) | GRASS GIS User's Manual | i.eb.hsebal01(1grass) |
NAME¶
i.eb.hsebal01 - Computes sensible heat flux iteration SEBAL 01.
KEYWORDS¶
imagery, energy balance, soil moisture, evaporative fraction, SEBAL
SYNOPSIS¶
i.eb.hsebal01
i.eb.hsebal01 --help
i.eb.hsebal01 [-ac] netradiation=name
soilheatflux=name aerodynresistance=name
temperaturemeansealevel=name
vapourpressureactual=name
frictionvelocitystar=float [row_wet_pixel=float]
[column_wet_pixel=float] [row_dry_pixel=float]
[column_dry_pixel=float] output=name
[--overwrite] [--help] [--verbose] [--quiet]
[--ui]
Flags:¶
Parameters:¶
- netradiation=name [required]
-
Name of instantaneous net radiation raster map [W/m2] - soilheatflux=name [required]
-
Name of instantaneous soil heat flux raster map [W/m2] - aerodynresistance=name [required]
-
Name of aerodynamic resistance to heat momentum raster map [s/m] - temperaturemeansealevel=name [required]
-
Name of altitude corrected surface temperature raster map [K] - vapourpressureactual=name [required]
-
Name of the actual vapour pressure (e_act) map [KPa] - frictionvelocitystar=float [required]
-
Value of the height independent friction velocity (u*) [m/s]
Default: 0.32407 - row_wet_pixel=float
-
Row value of the wet pixel - column_wet_pixel=float
-
Column value of the wet pixel - row_dry_pixel=float
-
Row value of the dry pixel - column_dry_pixel=float
-
Column value of the dry pixel - output=name [required]
-
Name for output sensible heat flux raster map [W/m2]
DESCRIPTION¶
i.eb.hsebal01 will calculate the sensible heat flux map (h0), given both maps of Net Radiation and soil Heat flux (Rn, g0) at instantaneous time, the surface roughness (z0m), a map of the altitude corrected temperature (t0dem), a point data of the frictional velocity (u*), a value of actual vapour pressure (ea[KPa]) and the (x,y) pairs for wet and dry pixels. Full process will need those:
- i.vi, i.albedo, r.latlong, i.emissivity
- i.evapo.potrad (GRASS Addon)
- i.eb.netrad, i.eb.soilheatflux, i.eb.hsebal01
- i.eb.evapfr, i.eb.eta
i.eb.hsebal01 performs the computation of sensible heat flux [W/m2] after Bastiaanssen, 1995 in [1], used in this form in 2001 by [2]. Implemented in this code in [3].
NOTES¶
- z0m can be alculated by i.eb.z0m or i.eb.z0m0 (GRASS Addons).
- ea can be calculated with standard meteorological data.
eoTmin=0.6108*EXP(17.27*Tmin/(Tmin+237.3))
eoTmax=0.6108*EXP(17.27*Tmax/(Tmax+237.3))
ea=(RH/100)/((eoTmin+eoTmax)/2) - t0dem = surface temperature + (altitude * 0.627 / 100)
REFERENCES¶
[1] 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)
[2] 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.
[3] 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)
[4] Chemin, Y., 2012. A Distributed Benchmarking Framework for Actual ET Models, in: Irmak, A. (Ed.), Evapotranspiration - Remote Sensing and Modeling. InTech. (PDF)
SEE ALSO¶
i.eb.soilheatflux, i.eb.evapfr
AUTHOR¶
Yann Chemin, International Rice Research Institute, Los Banos, The Philippines.
Contact: Yann Chemin
SOURCE CODE¶
Available at: i.eb.hsebal01 source code (history)
Accessed: Saturday Jul 27 17:09:00 2024
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