Tool Name	Evapotranspiration (Grid)
Tool ID	8
Library ID	climate_tools
Version	1.0
Author(s)	O.Conrad (c) 2015

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
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: 6
Day of Month	integer number	DAY		Minimum: 1 Maximum: 31 Default: 16
Latitude	floating point number	LAT	[Degree]	Minimum: -90.000000 Maximum: 90.000000 Default: 53.000000