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 (RL, 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 (RL, 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 (Rn, l) can then be obtained by differing the RL, D and the RL, U. The results showed that the RMSEs of the estimated RL, D and measured RL, D with the first method are smaller than those of with the ANN method for the sites over the Tibetan plateau region.