ESTIMATION OF DAILY NET SURFACE SHORTWAVE RADIATION FROM MODIS DATA

This work estimated firstly net surface shortwave radiation (NSSR) from MODIS/Aqua data with six visible and near infrared channels by re-parameterizing the methodology proposed by Tang et al. (2006). Comparison of the estimated NSSR with those simulated actual one showed that the root mean square error (RMSE) is 34.1 W/m(2). To validate the proposed parameterization scheme, some field measurements made at seven sites of the Surface Radiation Budget Network (SURFRAD) in October, 2008 were used. The result showed that the RMSE is 53.33 W/m(2). To accurately capture the diurnal variation of NSSR for cloudy skies, a simple and practical linear regression model by combing the instantaneous NSSRs estimated from MODIS/Terra at local solar time 10: 30 AM and MODIS/Aqua at 13: 30 PM has been proposed to estimate the daily average net surface shortwave radiation (DANSSR). The results showed that the RMSE between the estimated DANSSR and those calculated from the seven SURFRAD measurements for cloudy days in 2008 is 42.59 W/m(2).