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
- Author: O.Conrad (c) 2015
- Specification: grid
- Menu: Climate|Evapotranspiration
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Mean Temperature | Grid (input) | T | - | - |
| Minimum Temperature | Grid (input) | T_MIN | - | - |
| Maximum Temperature | Grid (input) | T_MAX | - | - |
| Output | Potential Evapotranspiration | Grid (output) | PET | - | - |
| Options | Latitude [Degree] | Floating point | LAT | - | Minimum: -90.000000
Maximum: 90.000000
Default: 53.000000 |
| 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: 2 |
| Day of Month | Integer | DAY | - | Minimum: 1
Maximum: 31
Default: 21 |
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: 2
-DAY:<num> Day of Month
Integer
Minimum: 1
Maximum: 31
Default: 21