Hi, After consulting with an atmospheric scientist, I have decided that it might be simpler to estimate 'real-sky' radiance as opposed to trying to estimate the Linke turbidity for the estimation of 'clear-sky' conditions.
It looks like r.sun can use input maps: coefbh and coefdh to compute real-sky radiance values. I would like to be sure that I am interpreting these inputs correctly: 1. does (1- coefbh) = coefdh ? 2. does coefdh correspond to the notion of the 'diffuse fraction' which is commonly calculated via something called the 'clearness index' ? If this is the case, then it is not all that difficult to compute coefdh from pyranometer data and the output from r.sun (mode 1) I will update the man page with my approach, if these assumptions are correct. cheers, PS: a relevent references is: Jacovides, C.; Tymvios, F.; Assimakopoulos, V. & Kaltsounides, N. Comparative study of various correlations in estimating hourly diffuse fraction of global solar radiation. Renewable Energy, 2006, 31, 2492 - 2504 -- Dylan Beaudette Soils and Biogeochemistry Graduate Group University of California at Davis 530.754.7341 _______________________________________________ grassuser mailing list [email protected] http://grass.itc.it/mailman/listinfo/grassuser
