Double-Nested Dynamical Downscaling Experiments over the Tibetan Plateau and Their Projection of Climate Change under Two RCP Scenarios

Abstract

AbstractA high-resolution regional climate model is used to simulate climate change over the Tibetan Plateau (TP). The model is driven at the grid spacing of 10 km by nesting the outputs of 50-km-resolution simulations. The results show that the models can capture the spatial and temporal distributions of the surface air temperature over the TP. The so-called double-nested method has a higher horizontal resolution and represents more spatial details. For example, the temperature simulations from the double-nested method reflect the observations better compared to the 50-km-resolution models. This is mainly due to the fact that topographical effects of complex terrains are detected better at higher resolution. Although both models can represent the basic patterns of precipitation, the simulated results are not as good as those of temperature. In the future, significant warming seems to develop over the TP under two representative concentration pathway (RCP) scenarios. Greater increases occur in December–February (DJF) compared with June–August (JJA). The increasing temperature trend is more pronounced over the Gangdese Mountains and over the Himalayas than in the central TP. The projection of precipitation shows the main increases in DJF. In JJA, it predicts decreases or slight changes in the southern TP. The comparison between RCP8.5 and RCP4.5 scenarios shows a similar spatial distributions of temperature and precipitation, whereas the respective values of RCP8.5 are enhanced compared with those under RCP4.5.