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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     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 18:55:23 +0100 (Sun, 25 Jan 2015) $

SOURCE CODE

       Available at: i.eb.hsebal01 source code (history)

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