.TH i.evapo.pt 1grass "" "GRASS 7.8.5" "GRASS GIS User's Manual"
.SH NAME
\fI\fBi.evapo.pt\fR\fR  \- Computes evapotranspiration calculation Priestley and Taylor formulation, 1972.
.SH KEYWORDS
imagery, evapotranspiration
.SH SYNOPSIS
\fBi.evapo.pt\fR
.br
\fBi.evapo.pt \-\-help\fR
.br
\fBi.evapo.pt\fR [\-\fBz\fR] \fBnet_radiation\fR=\fIname\fR \fBsoil_heatflux\fR=\fIname\fR \fBair_temperature\fR=\fIname\fR \fBatmospheric_pressure\fR=\fIname\fR \fBpriestley_taylor_coeff\fR=\fIfloat\fR \fBoutput\fR=\fIname\fR  [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-z\fR" 4m
.br
Set negative ETa to zero
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBnet_radiation\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of input net radiation raster map [W/m2]
.IP "\fBsoil_heatflux\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of input soil heat flux raster map [W/m2]
.IP "\fBair_temperature\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of input air temperature raster map [K]
.IP "\fBatmospheric_pressure\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of input atmospheric pressure raster map [millibars]
.IP "\fBpriestley_taylor_coeff\fR=\fIfloat\fR \fB[required]\fR" 4m
.br
Priestley\-Taylor coefficient
.br
Default: \fI1.26\fR
.IP "\fBoutput\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of output evapotranspiration raster map [mm/d]
.SH DESCRIPTION
\fIi.evapo.pt\fR Calculates the diurnal evapotranspiration after Prestley
and Taylor (1972). The Priestley\-Taylor model (Priestley and Taylor, 1972)
is a modification of Penman\(cqs more theoretical equation.
.SH NOTES
RNETD optional output from \fIi.evapo.potrad\fR is giving good results as input
for net radiation in this module.
.PP
Alpha values:
.RS 4n
.IP \(bu 4n
1.32 for estimates from vegetated areas as a result of the increase in
surface roughness (Morton, 1983; Brutsaert and Stricker, 1979)
.IP \(bu 4n
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)
.IP \(bu 4n
1.74 has been recommended for estimating potential evapotranspiration
in more arid regions (ASCE, 1990). This worked well in Greece with University
of Thessaloniki.
.RE
Alpha values extracted from:
Watflood manual.
.SH SEE ALSO
\fI
i.evapo.mh,
i.evapo.pm,
i.evapo.time,
i.eb.netrad,
r.sun
\fR
.SH AUTHORS
Yann Chemin, GRASS Development Team, 2007\-08
.SH SOURCE CODE
.PP
Available at: i.evapo.pt source code (history)
.PP
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.PP
© 2003\-2020
GRASS Development Team,
GRASS GIS 7.8.5 Reference Manual