Estimation of net shortwave radiation flux of western Himalayan snow cover during clear sky days using remote sensing and meteorological data

The aim of this letter is to estimate incoming and net shortwave radiation fluxes of large snow-covered area of western Himalaya and to evaluate the results with in situ observations. Radiation fluxes are estimated at spatial levels using remote sensing data from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor and Shuttle Radar Topographic Mission (SRTM) digital elevation model (DEM), supplemented with sparse field data obtained from automatic weather stations (AWSs). Snow cover albedo has been estimated from MODIS data using narrowband to broadband conversion method for clear sky days. Geospatial maps of air temperature (T-a) and relative humidity (RH) have been generated for the study area using AWS recorded T-a/RH and DEM. Parameterization techniques have been used for estimating incoming and net shortwave radiation fluxes, which have been validated from in situ AWS observations. The root mean square error (RMSE) in estimation of incoming shortwave radiation flux and net shortwave radiation flux has been found to be 75 and 84.9Wm(-2), respectively. Further, the higher radiation fluxes have been observed on south aspect slopes than those observed on north aspect slopes.