1i.evapo.pt(1)               GRASS GIS User's Manual              i.evapo.pt(1)
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NAME

6       i.evapo.pt   -  Computes  evapotranspiration  calculation Priestley and
7       Taylor formulation, 1972.
8

KEYWORDS

10       imagery, evapotranspiration
11

SYNOPSIS

13       i.evapo.pt
14       i.evapo.pt --help
15       i.evapo.pt  [-z]  net_radiation=name  soil_heatflux=name   air_tempera‐
16       ture=name  atmospheric_pressure=name  priestley_taylor_coeff=float out‐
17       put=name  [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]
18
19   Flags:
20       -z
21           Set negative ETa to zero
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23       --overwrite
24           Allow output files to overwrite existing files
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26       --help
27           Print usage summary
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29       --verbose
30           Verbose module output
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32       --quiet
33           Quiet module output
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35       --ui
36           Force launching GUI dialog
37
38   Parameters:
39       net_radiation=name [required]
40           Name of input net radiation raster map [W/m2]
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42       soil_heatflux=name [required]
43           Name of input soil heat flux raster map [W/m2]
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45       air_temperature=name [required]
46           Name of input air temperature raster map [K]
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48       atmospheric_pressure=name [required]
49           Name of input atmospheric pressure raster map [millibars]
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51       priestley_taylor_coeff=float [required]
52           Priestley-Taylor coefficient
53           Default: 1.26
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55       output=name [required]
56           Name of output evapotranspiration raster map [mm/d]
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DESCRIPTION

59       i.evapo.pt Calculates the diurnal evapotranspiration after Prestley and
60       Taylor  (1972). The Priestley-Taylor model (Priestley and Taylor, 1972)
61       is a modification of Penman’s more theoretical equation.
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NOTES

64       RNETD optional output from i.evapo.potrad is giving good results as in‐
65       put for net radiation in this module.
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67       Alpha values:
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69           •   1.32  for estimates from vegetated areas as a result of the in‐
70               crease  in  surface  roughness  (Morton,  1983;  Brutsaert  and
71               Stricker, 1979)
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73           •   1.26  is  applicable  in  humid climates (De Bruin and Keijman,
74               1979; Stewart and Rouse, 1976; Shuttleworth and Calder,  1979),
75               and temperate hardwood swamps (Munro, 1979)
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77           •   1.74  has  been recommended for estimating potential evapotran‐
78               spiration in more arid regions (ASCE, 1990). This  worked  well
79               in Greece with University of Thessaloniki.
80       Alpha values extracted from: Watflood manual.
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SEE ALSO

83        i.evapo.mh, i.evapo.pm, i.evapo.time, i.eb.netrad, r.sun
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AUTHOR

86       Yann Chemin, GRASS Development Team, 2007-08
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SOURCE CODE

89       Available at: i.evapo.pt source code (history)
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91       Accessed: Saturday Jan 21 21:16:37 2023
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93       Main  index | Imagery index | Topics index | Keywords index | Graphical
94       index | Full index
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96       © 2003-2023 GRASS Development Team, GRASS GIS 8.2.1 Reference Manual
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100GRASS 8.2.1                                                      i.evapo.pt(1)
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