Dear Nat Cap Team.

For the Water Yield model, I need to compute reference evapotranspiration. I am using a modified Hargreaves Equation for the computation of reference evapotranspiration. For the equation, we need a value of RA which is extraterrestrial radiation. As mentioned on InVEST user guidelines, I checked FAO irrigation drainage paper 56 which has values for radiation in its Annex 2.

The values are for integer latitude degrees. As my stations are on decimal latitude degrees, can I interpolate it from two values? For a clear illustration, for Feb month on 34-degree latitude, RA value is 39.2 and for 36-degree latitude, RA value is 38.9. My station is on latitude 34.5 degrees. So I basically interpolate it between 34 and 36 degree or is there any other way to find value for 34.5 degree Lat?

Hoping for your response.