Numerical Simulation Of Regional Climate Change In China By RegCM4

This study analyses the regional climate change in China for2041-2060under IPCC A1B scenario by a high resolution regional model, RegCM4. Compared with the global general circulation model (GCM), regional climate model can describe the small and medium scale topography、 landscape and hydrological conditions better. It can get more reliable simulation and prediction results than that simulated alone by GCM, so it has been widely applied in climate change research. In this study, the RegCM4is nested in one-way mode within the EH50M. Two sets of multi-decadal simulations at50-km grid spacing for contemporary climate(1980-1999) and future climate(2041-2060) are conducted. According to the results of numerical simulation experiments to get the climate simulation performance of China area and then discuss the climate change in the future over China area under the A1B scenario. The main conclusions of this study are summarized as follow:1. It is important to do some performance tests for the latest regional climate model RegCM4with a lot of improvement. The sensitivity experiments for parameterized scheme of physical and the lateral boundary condition are done. The results show that the exponential relaxation lateral boundary and the Emanuel connective precipitation scheme are suitable for the simulation in China by the regional climate model RegCM4.2. The contemporary climate is simulated over China from1980-1999by the RegCM4based on the parameters established in the sensitive test it aims to examine the simulation performance compared with the observational data. The results show that the simulation of the temperature is close to the observation, especially in the spatial distribution and the seasonal variation of the temperature. It also successfully simulates the temperature distribution area of high value and low value; the temperature reduces with increasing latitude in the Eastern region; there is a good simulation about the temperature caused by terrain but a1-3℃cold deviation in the value. But the simulation performance of precipitation is not as good as temperature. The rain belt location simulated is different from the observation and the simulated precipitation is greater than the observed value. The bias is higher in the northern region and small high in the southern. There is virtual precipitation in the area with a large terrain gradient, especially in the southeast region of the Qinghai-Tibet Plateau.3. Under the AlB scenario the RegCM4is nested within EH50M to simulate the future climate over China from2041-2060year. The results show that: the regional temperature would increase in mid-2000s century under the A1B scenario. The magnitude of the temperature increase is larger in the northern than that in the southern and the western temperature would increase higher than that in the eastern. The rate of warming would be from1.5℃in the southeast coast to the2.4℃in the northwest region and reach3℃in some areas. The warming rate of the Qinghai-Tibet Plateau is the highest. The change of precipitation is different from the temperature. The precipitation in the northern and the western region would increase, but its decrease in the southern particularly in the southeast region. In addition, the precipitation of southwest would be reduced.