DESCRIPTION

i.evapo.senay Calculates the diurnal actual evapotranspiration after Senay (2007). This is converting all Net radiation from the diurnal period into ET, then uses Senay equation for evaporative fraction.

It takes input maps of Albedo, surface skin temperature, latitude, day of year, single-way transmissivity and takes input value of the density of fresh water.

DEM is used for calculating min and max temperature for Senay equation.

The "-s" flag permits output map of evaporative fraction from Senay.

NOTES

If you are trying to map irrigated crops, and you know there is at least one crop pixel that is evapotranspiring at maximum (ETa=ETpot), then read this.

i.evapo.senay is highly dependent on the wet pixel being the lowest temperature in the crop pixels to work for non water stressed crops, force it that way, even if it breaks non crop areas. I suggest you reduce your region to the irrigation system boundaries, checking that it includes a bit of dry area for the hot/dry pixel.

Since it is a direct relationship to LST, evaporative fraction can be very sensitive to the kind of pixel sample you feed it with.

TODO

SEE ALSO

r.sun
i.albedo
i.eb.eta
i.eb.evapfr
i.evapo.potrad

REFERENCES

Chemin, Y., 2012. A Distributed Benchmarking Framework for Actual ET Models, in: Irmak, A. (Ed.), Evapotranspiration - Remote Sensing and Modeling. InTech. (PDF)

AUTHOR

Yann Chemin, International Rice Research Institute, The Philippines.

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