Daily extraterrestrial radiation (Ra) for different latitudes

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.
But after I downloaded the PDF file, I found that the 2.6 and 2.7 tables in Annex 2 are blank. So could you please provide me a table named Daily extraterrestrial radiation (Ra) for different latitudes?
Thank you very much!

Hi @sunsiqi -

Strange that those tables are blank, but you can just search the web and find those tables. For example, I just found them here on the FAO site.

~ Stacie

1 Like

That helped me a lot,

Thank you very much!

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