i.eb.hsebal01.1grass man page

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) $

Main index | Imagery index | Topics index | Keywords index | Full index

© 2003-2016 GRASS Development Team, GRASS GIS 7.0.4 Reference Manual

Info

GRASS 7.0.4 Grass User's Manual