SAGA-GIS Module Library Documentation (v2.2.3)

Module PET (after Hargreaves, Grid)

Estimation of daily potential evapotranspiration from daily average, minimum and maximum temperatures using Hargreave's empirical equation. In order to estimate extraterrestrial net radiation geographic latitude of observation and Julian day have to be supplied too.
References:
- Ambikadevi, K.M. (2004): Simulation of Evapotranspiration and Rainfall-runoff for the Stillwater River Watershed in Central Massachusetts. Environmental & Water Resources Engineering Masters Projects, University of Massachusetts, Amherst online
- Hargraeves, G.H., Samani, Z.A. (1985): Reference crop evapotranspiration from ambient air temperatures. Paper presented in ASAE Regional Meeting, Grand Junction, Colorado. online
Allen, R.G., Pereira, L.S., Raes, D., Smith, M. (1998): Crop evapotranspiration - Guidelines for computing crop water requirements. FAO Irrigation and drainage paper 56. online

Parameters

 NameTypeIdentifierDescriptionConstraints
InputMean TemperatureGrid (input)T--
Minimum TemperatureGrid (input)T_MIN--
Maximum TemperatureGrid (input)T_MAX--
OutputPotential EvapotranspirationGrid (output)PET--
OptionsLatitude [Degree]Floating pointLAT-Minimum: -90.000000
Maximum: 90.000000
Default: 53.000000
TimeChoiceTIME-Available Choices:
[0] day
[1] month
Default: 0
MonthChoiceMONTH-Available Choices:
[0] January
[1] February
[2] March
[3] April
[4] May
[5] June
[6] July
[7] August
[8] September
[9] October
[10] November
[11] December
Default: 11
Day of MonthIntegerDAY-Minimum: 1
Maximum: 31
Default: 17

Command-line

Usage: saga_cmd climate_tools 8 [-T <str>] [-T_MIN <str>] [-T_MAX <str>] [-PET <str>] [-LAT <str>] [-TIME <str>] [-MONTH <str>] [-DAY <num>]
  -T:<str>    	Mean Temperature
	Grid (input)
  -T_MIN:<str>	Minimum Temperature
	Grid (input)
  -T_MAX:<str>	Maximum Temperature
	Grid (input)
  -PET:<str>  	Potential Evapotranspiration
	Grid (output)
  -LAT:<str>  	Latitude [Degree]
	Floating point
	Minimum: -90.000000
	Maximum: 90.000000
	Default: 53.000000
  -TIME:<str> 	Time
	Choice
	Available Choices:
	[0] day
	[1] month
	Default: 0
  -MONTH:<str>	Month
	Choice
	Available Choices:
	[0] January
	[1] February
	[2] March
	[3] April
	[4] May
	[5] June
	[6] July
	[7] August
	[8] September
	[9] October
	[10] November
	[11] December
	Default: 11
  -DAY:<num>  	Day of Month
	Integer
	Minimum: 1
	Maximum: 31
	Default: 17