Hello, for some calculation with r.sun i need to know if this method is possible:
I've got the Cloud-Index n from satel-light.com aggergated in daily values. To calculate the Clear-Sky-Index Kc against the Cloud-Index I use the formulars on the basis of Fontoynont et al. n =< -0,2, Kc=1,2 0,2 =< n =< 0,8 Kc=1-n 0,8 =< n =< 1,1 Kc=2,066-3,6667n+1,6667n^2 n >= 1,1 Kc=0,05 Now r.sun calculates the beam and diffuse irradiation unter cloudless (clear) conditions. I want to sum these two values in order received the global horizontal solar irradiation Ghc. To get the global horizontal solar irradiation for Clear-Sky-Situation, i convert the Kc=Gh/Ghc into Gh=Ghc*Kc with values of the calculated Kc above. The reason for this computation: I want to declare how much energy (only global irradiation) with and wihtout cloudiness exists on a predfined area. I choose this way because we have no other data excepting the Cloud-Index. Now the question: is this calculation possible AND valid or are there some other parameters which have to be mentioned (and incorporate)? Thanks a lot, Diana _______________________________________________ grassuser mailing list [email protected] http://grass.itc.it/mailman/listinfo/grassuser
