Estimation of net surface longwave radiation for the Tibetan plateau region using MODIS data

This paper proposed two methods to estimate the instantaneous downwelling surface longwave radiation (R_{L, D}) using the MODIS measurements observed at the top of the atmosphere (TOA) over the Tibetan plateau region for clear-sky conditions. One is the method proposed by [2] and refined in this work, and the other is an artificial neural network (ANN) method. The upwelling surface longwave radiation (R_{L, U}) was estimated using the Stefan-Boltzmann law with MODIS surface temperature/emissivity products (MOD11_L2). The two methods are all based on the atmospheric transfer simulation. The net surface longwave radiation (R_{n, l}) can then be obtained by differing the R_{L, D} and the R_{L, U}. The results showed that the RMSEs of the estimated R_{L, D} and measured R_{L, D} with the first method are smaller than those of with the ANN method for the sites over the Tibetan plateau region.