table of contents
i.evapo.pt(1grass) | GRASS GIS User's Manual | i.evapo.pt(1grass) |
NAME¶
i.evapo.pt - Computes evapotranspiration calculation Priestley and Taylor formulation, 1972.
KEYWORDS¶
imagery, evapotranspiration
SYNOPSIS¶
i.evapo.pt
i.evapo.pt --help
i.evapo.pt [-z] net_radiation=name
soil_heatflux=name air_temperature=name
atmospheric_pressure=name
priestley_taylor_coeff=float output=name
[--overwrite] [--help] [--verbose] [--quiet]
[--ui]
Flags:¶
Parameters:¶
- net_radiation=name [required]
-
Name of input net radiation raster map [W/m2] - soil_heatflux=name [required]
-
Name of input soil heat flux raster map [W/m2] - air_temperature=name [required]
-
Name of input air temperature raster map [K] - atmospheric_pressure=name [required]
-
Name of input atmospheric pressure raster map [millibars] - priestley_taylor_coeff=float [required]
-
Priestley-Taylor coefficient
Default: 1.26 - output=name [required]
-
Name of output evapotranspiration raster map [mm/d]
DESCRIPTION¶
i.evapo.pt Calculates the diurnal evapotranspiration after Prestley and Taylor (1972). The Priestley-Taylor model (Priestley and Taylor, 1972) is a modification of Penman’s more theoretical equation.
NOTES¶
RNETD optional output from i.evapo.potrad is giving good results as input for net radiation in this module.
Alpha values:
- 1.32 for estimates from vegetated areas as a result of the increase in surface roughness (Morton, 1983; Brutsaert and Stricker, 1979)
- 1.26 is applicable in humid climates (De Bruin and Keijman, 1979; Stewart and Rouse, 1976; Shuttleworth and Calder, 1979), and temperate hardwood swamps (Munro, 1979)
- 1.74 has been recommended for estimating potential evapotranspiration in more arid regions (ASCE, 1990). This worked well in Greece with University of Thessaloniki.
SEE ALSO¶
i.evapo.mh, i.evapo.pm, i.evapo.time, i.eb.netrad, r.sun
AUTHOR¶
Yann Chemin, GRASS Development Team, 2007-08
SOURCE CODE¶
Available at: i.evapo.pt source code (history)
Accessed: Saturday Jul 27 17:09:00 2024
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