Can you help me to calculate solar radiation from GTOPO30 DEM image at the 30 m spatial resolution. I'm trying to do this many times using spatial analysis-solar radiation calculation tool in arcgis. But there always appeared error message saying unknown problem. what does it mean? Is there anyone who has a experince with this. your suggestion will help me a lot.
The solar radiation calculation is computationally expensive, and it isn't something that can be run on extremely large regions. I've run it on a 250 km^2 area which took three days at a low resolution, so it may not be feasible to do for all of Mongolia. See this thread and the help page for further background on the constraints. If you are set on performing the analysis, divide up your raster into small regions, and run it independently on each. With a little experimentation, you should be able to determine the size at which it runs reliably.