i.eb.hsebal01 - GRASS GIS manual

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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:

-a: Automatic wet/dry pixel (careful!)
-c: Dry/Wet pixels coordinates are in image projection, not row/col
--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:

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
NOTES
REFERENCES
SEE ALSO
AUTHOR

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

(for time integration: i.evapo.time_integration)

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)