Evapotranspiration (Grid)

Author(s)	O.Conrad (c) 2015
Library ID	climate_tools
Tool ID	8
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

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	Mean Temperature	grid, input, optional	`T`	[°C]	-
	Minimum Temperature	grid, input, optional	`T_MIN`	[°C]	-
	Maximum Temperature	grid, input, optional	`T_MAX`	[°C]	-
	Relative Humidity	grid, input, optional	`RH`	[%]	-
	Solar Radiation	grid, input, optional	`SR`	[J/cm²]	-
	Wind Speed	grid, input, optional	`WS`	[m/s]	-
	Air Pressure	grid, input, optional	`P`	[kPa]	-
Output	Potential Evapotranspiration	grid, output	`ET`	-	-
Options	Grid System	grid system	`PARAMETERS_GRID_SYSTEM`	-	-
	Default	floating point number	`T_DEFAULT`	default value if no grid has been selected	Minimum: -273.150000 Default: 10.000000
	Default	floating point number	`T_MIN_DEFAULT`	default value if no grid has been selected	Minimum: -273.150000 Default: 0.000000
	Default	floating point number	`T_MAX_DEFAULT`	default value if no grid has been selected	Minimum: -273.150000 Default: 20.000000
	Default	floating point number	`RH_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Maximum: 100.000000 Default: 50.000000
	Default	floating point number	`SR_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Default: 2.000000
	Default	floating point number	`WS_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Default: 5.000000
	Default	floating point number	`P_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Default: 101.300000
	Method	choice	`METHOD`	-	Available Choices: [0] Turc [1] Hargreave [2] Penman (simplified) [3] Penman-Monteith Default: 0
	Estimate Solar Radiation	boolean	`SR_EST`	Estimate solar radiation from date, latitudinal position and sunshine duration as percentage of its potential maximum.	Default: 0
	Sunshine Duration	floating point number	`SUNSHINE`	Daily sunshine duration as percentage of its potential maximum.	Minimum: 0.000000 Maximum: 100.000000 Default: 50.000000
	Time	choice	`TIME`	-	Available Choices: [0] day [1] month Default: 0
	Month	choice	`MONTH`	-	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: 4
	Day of Month	integer number	`DAY`	-	Minimum: 1 Maximum: 31 Default: 11
	Latitude	floating point number	`LAT`	[Degree]	Minimum: -90.000000 Maximum: 90.000000 Default: 53.000000

Command Line


Usage: saga_cmd climate_tools 8 [-T ] [-T_DEFAULT ] [-T_MIN ] [-T_MIN_DEFAULT ] [-T_MAX ] [-T_MAX_DEFAULT ] [-RH ] [-RH_DEFAULT ] [-SR ] [-SR_DEFAULT ] [-WS ] [-WS_DEFAULT ] [-P ] [-P_DEFAULT ] [-ET ] [-METHOD ] [-SR_EST ] [-SUNSHINE ] [-TIME ] [-MONTH ] [-DAY ] [-LAT ]
  -T:                  Mean Temperature
	grid, input, optional
  -T_DEFAULT:       Default
	floating point number
	Minimum: -273.150000
	Default: 10.000000
  -T_MIN:              Minimum Temperature
	grid, input, optional
  -T_MIN_DEFAULT:   Default
	floating point number
	Minimum: -273.150000
	Default: 0.000000
  -T_MAX:              Maximum Temperature
	grid, input, optional
  -T_MAX_DEFAULT:   Default
	floating point number
	Minimum: -273.150000
	Default: 20.000000
  -RH:                 Relative Humidity
	grid, input, optional
  -RH_DEFAULT:      Default
	floating point number
	Minimum: 0.000000
	Maximum: 100.000000
	Default: 50.000000
  -SR:                 Solar Radiation
	grid, input, optional
  -SR_DEFAULT:      Default
	floating point number
	Minimum: 0.000000
	Default: 2.000000
  -WS:                 Wind Speed
	grid, input, optional
  -WS_DEFAULT:      Default
	floating point number
	Minimum: 0.000000
	Default: 5.000000
  -P:                  Air Pressure
	grid, input, optional
  -P_DEFAULT:       Default
	floating point number
	Minimum: 0.000000
	Default: 101.300000
  -ET:                 Potential Evapotranspiration
	grid, output
  -METHOD:
                            Method
                            	choice
                            	Available Choices:
                            	[0] Turc
                            	[1] Hargreave
                            	[2] Penman (simplified)
                            	[3] Penman-Monteith
                            	Default: 0
  -SR_EST:             Estimate Solar Radiation
	boolean
	Default: 0
  -SUNSHINE:
                            Sunshine Duration
                            	floating point number
                            	Minimum: 0.000000
                            	Maximum: 100.000000
                            	Default: 50.000000
  -TIME:               Time
	choice
	Available Choices:
	[0] day
	[1] month
	Default: 0
  -MONTH:
                            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: 4
  -DAY:                Day of Month
	integer number
	Minimum: 1
	Maximum: 31
	Default: 11
  -LAT:             Latitude
	floating point number
	Minimum: -90.000000
	Maximum: 90.000000
	Default: 53.000000