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| 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.
 +|-
 +|-
 +| '''Optional: relative humidity (%)'''
 +| Maximum and minimum relative humidity during the day.
 +| Although this parameter is not essential it improves the ET<sub>0</sub> calculations substantially.
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|} |}
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-* 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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Revision as of 08:34, 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.
Optional: relative humidity (%) Maximum and minimum relative humidity during the day. Although this parameter is not essential it improves the ET0 calculations substantially.



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