i.eb.eta - GRASS GIS manual
Author: GRASS Development Team
Description: i.eb.eta: Actual evapotranspiration for diurnal period (Bastiaanssen, 1995).
Keywords: imagery, energy balance, actual evapotranspiration, SEBAL

## NAME

i.eb.eta - Actual evapotranspiration for diurnal period (Bastiaanssen, 1995).

## KEYWORDS

imagery, energy balance, actual evapotranspiration, SEBAL

## SYNOPSIS

i.eb.eta
i.eb.eta --help
i.eb.eta netradiationdiurnal=name evaporativefraction=name temperature=name output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]

### Flags:

--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:

netradiationdiurnal=name [required]
  Name of the diurnal net radiation map [W/m2]
  Default: rnetday
evaporativefraction=name [required]
  Name of the evaporative fraction map [-]
  Default: evapfr
temperature=name [required]
  Name of the surface skin temperature [K]
  Default: tempk
output=name [required]
  Name of the output actual evapotranspiration layer [mm/d]

## DESCRIPTION

i.eb.eta calculates the actual evapotranspiration (ETa ; mm/d) for diurnal period after [1], implemented in [3]. It takes input of Diurnal Net Radiation (see r.sun), evaporative fraction (see i.eb.evapfr) and surface skin temperature.

## NOTES

Full ETa processing 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)

For more details on the algorithms see [1][2][3][4].

## SEE ALSO

r.sun, i.eb.evapfr, i.eb.netrad

## 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, Asian Institute of Technology, Thailand

## SOURCE CODE

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

Accessed: Sunday Jun 21 00:54:58 2026

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