i.evapo.time(1grass) | GRASS GIS User's Manual | i.evapo.time(1grass) |
i.evapo.time - Computes temporal integration of satellite ET actual (ETa) following the daily ET reference (ETo) from meteorological station(s).
imagery, evapotranspiration
i.evapo.time
i.evapo.time --help
i.evapo.time eta=name[,name,...]
eta_doy=name[,name,...]
eto=name[,name,...] eto_doy_min=float
start_period=float end_period=float
output=name [--overwrite] [--help]
[--verbose] [--quiet] [--ui]
i.evapo.time (i.evapo.time_integration) integrates ETa in time following a reference ET (typically) from a set of meteorological stations dataset. Inputs:
representative days calculation: let assume i belongs to range
[DOYmin;DOYmax]
DOYbeforeETa[i] = ( DOYofETa[i] - DOYofETa[i-1] ) / 2 DOYafterETa[i] = ( DOYofETa[i+1] - DOYofETa[i] ) / 2
ETo images preparation: If you only have one meteorological
station data set, the easiest way is:
n=0 for ETo_val in Eto[1] Eto[2] ... do r.mapcalc "eto$n = $ETo_val" `expr n = n + 1` done
with Eto[1], Eto[2], etc being a simple copy and paste from your data file of all ETo values separated by an empty space from each other.
If you have several meteorological stations data, then you need to grid them by generating Thiessen polygons or using different interpolation methods for each day.
For multi-year calculations, just continue incrementing DOY values above 366, it will continue working, up to maximum input of 400 satellite images.
i.eb.eta, i.evapo.mh, i.evapo.pt, i.evapo.pm, r.sun
Yann Chemin, International Rice Research Institute, The Philippines
Available at: i.evapo.time source code (history)
Accessed: Sunday Jan 22 07:37:26 2023
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