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 frictionvelocitystar=float vapourpressureactual=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]

       frictionvelocitystar=float [required]
           Value of the height independent friction velocity (u*) [m/s]
           Default: 0.32407

       vapourpressureactual=float [required]
           Value of the actual vapour pressure (e_act) [KPa]
           Default: 1.511

       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
       (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)

SEE ALSO

        i.eb.soilheatflux, i.eb.hsebal01, i.eb.evapfr

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)

AUTHORS

       Yann Chemin, International Rice Research Institute, Los Banos, The Philippines.

       Contact: Yann Chemin

       Last changed: $Date: 2015-01-25 18:56:33 +0100 (Sun, 25 Jan 2015) $

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       © 2003-2016 GRASS Development Team, GRASS GIS 7.0.3 Reference Manual

GRASS 7.0.3                                                                                i.eb.hsebal01(1grass)