Evapotranspiration (Table)

Author(s)	O.Conrad (c) 2011
Library ID	climate_tools
Tool ID	6
Version	1.0
Menu	Climate and Weather \| Evapotranspiration

Description

Estimation of daily potential evapotranspiration from weather data with different methods. Besides mean daily temperature it depends on the chosen method which additional data has to be provided. In order to estimate extraterrestrial net radiation some of the methods need to know the location's geographic latitude and the date's Julian day number.

References

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. Link

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. Link

DVWK (1996): Ermittlung der Verdunstung von Land- u. Wasserflaechen. Merkblaetter 238/1996.

Hargreaves, G.H., Samani, Z.A. (1985): Reference crop evapotranspiration from ambient air temperatures. Paper presented in ASAE Regional Meeting, Grand Junction, Colorado. Link

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Data	table, input	`TABLE`	-	-
Output	Results	table, output, optional	`RESULT`	-	-
Options	Mean Temperature	table field	`T`	[°C]	-
	Minimum Temperature	table field	`T_MIN`	[°C]	-
	Maximum Temperature	table field	`T_MAX`	[°C]	-
	Relative Humidity	table field	`RH`	[%]	-
	Solar Radiation	table field	`SR`	daily sum of global horizontal irradiance [J/cm²]	-
	Wind Speed	table field	`WS`	daily mean of wind speed at 2m above ground [m/s]	-
	Air Pressure	table field	`P`	[kPa]	-
	Date	table field	`DATE`	-	-
	Evapotranspiration	table field	`ET`	-	-
	Latitude	floating point number	`LAT`	-	Minimum: -90.000000 Maximum: 90.000000 Default: 53.000000
	Method	choice	`METHOD`	-	Available Choices: [0] Turc [1] Hargreave [2] Penman (simplified) [3] Penman-Monteith Default: 0

Command Line


Usage: saga_cmd climate_tools 6 [-TABLE ] [-RESULT ] [-T ] [-T_MIN ] [-T_MAX ] [-RH ] [-SR ] [-WS ] [-P ] [-DATE ] [-ET ] [-LAT ] [-METHOD ]
  -TABLE:    Data
	table, input
  -RESULT:   Results
	table, output, optional
  -T:        Mean Temperature
	table field
  -T_MIN:    Minimum Temperature
	table field
  -T_MAX:    Maximum Temperature
	table field
  -RH:       Relative Humidity
	table field
  -SR:       Solar Radiation
	table field
  -WS:       Wind Speed
	table field
  -P:        Air Pressure
	table field
  -DATE:     Date
	table field
  -ET:       Evapotranspiration
	table field
  -LAT:   Latitude
	floating point number
	Minimum: -90.000000
	Maximum: 90.000000
	Default: 53.000000
  -METHOD:
                  Method
                  	choice
                  	Available Choices:
                  	[0] Turc
                  	[1] Hargreave
                  	[2] Penman (simplified)
                  	[3] Penman-Monteith
                  	Default: 0