1i.evapo.pt(1) GRASS GIS User's Manual i.evapo.pt(1)
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6 i.evapo.pt - Computes evapotranspiration calculation Priestley and
7 Taylor formulation, 1972.
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10 imagery, evapotranspiration
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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]
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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
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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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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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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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83 i.evapo.mh, i.evapo.pm, i.evapo.time, i.eb.netrad, r.sun
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86 Yann Chemin, GRASS Development Team, 2007-08
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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)