ESTIMATION OF NET SURFACE LONGWAVE RADIATION FOR THE TIBETAN PLATEAU REGION USING MODIS DATA

摘要

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 (MOD11L2). 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 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.