How does the Weather Generator calculate potential evapotranspiration?

Potential evapotransipration (PET) was calculated using a FAO-modified version of the Penman method.

In detail

The Weather Generator calculates potential evapotranspiration using a FAO-modified version of the Penman method. This defines PET as the potential evapotranspiration from a clipped grass surface 0.12 m in height with a bulk surface resistance of 70 s m-1 and an assumed surface albedo of 0.23. All variables are assumed to be measured at a height of 2 m, apart from wind which was measured at 10 m. In order to convert the wind measurements to
2 m, a conversion factor was applied based on the logarithmic wind profile.

The formula used to calculate the PET can be found in the paper by Ekstrom et al.

Find out more

• Ekstrom et al, Regional climate model data used within the SWURVE project. 1: Projected changes in seasonal patterns and estimation of PET. Hydrol. Earth Syst. Sci., 11(3), 1069-1083, 2007.