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('''Chapter 11. Development of ET<sub>0</sub> computation procedure.''')
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('''Chapter 11. Development of ET<sub>0</sub> computation procedure.''')
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Line 10: Line 10:
| '''Remarks''' | '''Remarks'''
|- |-
-| Temperature+| '''Temperature'''
| Maximum and minimum temperature | Maximum and minimum temperature
| Some ET<sub>0</sub> calculation methods use average temperature only. AgrometShell needs both minimum and maximum temperatures. | Some ET<sub>0</sub> calculation methods use average temperature only. AgrometShell needs both minimum and maximum temperatures.
|- |-
|- |-
-| Radiation (MJ/m<sup>2</sup>+| '''Radiation (MJ/m<sup>2</sup>)'''
| Global radiation | Global radiation
| Global radiation can be calculated from sunshine hours or sunshine fraction accompanied by latitude and day in the year (Julian Date). | Global radiation can be calculated from sunshine hours or sunshine fraction accompanied by latitude and day in the year (Julian Date).
|- |-
-| Wind Speed (m/sec>+| '''Wind Speed (m/sec)'''
| Wind speed at 2 meters | Wind speed at 2 meters
| Formulas are available to convert wind speed for other heights (e.g. 10 meters) into a 2 meter value. | Formulas are available to convert wind speed for other heights (e.g. 10 meters) into a 2 meter value.

Revision as of 08:32, 4 August 2006

Chapter 11. Development of ET0 computation procedure.

Potential evapotranspiration (ET0) is a vital input to Water Balance calculations, which in turn are a vital part in Crop forecasting. The parameters needed to calculate ET0 are the following:

Parameter group Parameters Remarks
Temperature Maximum and minimum temperature Some ET0 calculation methods use average temperature only. AgrometShell needs both minimum and maximum temperatures.
Radiation (MJ/m2) Global radiation Global radiation can be calculated from sunshine hours or sunshine fraction accompanied by latitude and day in the year (Julian Date).
Wind Speed (m/sec) Wind speed at 2 meters Formulas are available to convert wind speed for other heights (e.g. 10 meters) into a 2 meter value.


  • Temperatures : minimum and maximum in degrees celcius
  • Radiation. Radiation can be calculated quite accurately from the number of sunshine hours (or sunshine fraction) accompanied by Day number in the year





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