For long term simulation in GSSHA, where can we download direct and global radiation? I downloaded other hydrometeorology parameters (Pressure, Sky Cover, Wind Speed and Temperature) from NCDC website (http://gis.ncdc.noaa.gov/map/viewer/#app=cdo). Relative Humidity was estimated based on dew point and average temperature using this formula: RH: =100*(EXP((17.625*TD)/(243.04+TD))/EXP((17.625*T)/(243.04+T))) Is there any other recommended method for Relative Humidity estimation?