温室效应引起的中国区域气候变化的数值模拟Ⅰ:模式对中国气候模拟能力的检验

CLIMATE CHANGE DUE TO GREENHOUSE EFFECTS IN CHINA AS SIMULATED BY A REGIONAL CLIMATE MODEL PART I: EVALUATION OF THE MODEL SIMULATIONS

使用RegCM2区域气候模式单向嵌套澳大利亚CSIRO R21L9全球海-气耦合模式,进行了CO2加倍对中国区域气候变化影响的数值试验研究,分析了控制试验(1×CO2)即模式对中国当代气候的模拟情况。首先给出了全球模式控制试验在中国地区的结果,分析表明它对中国区域的地面气温和降水具有一定的模拟能力,其结果可以用来制作驱动区域气候模式的初始场和侧边界。对RegCM2 5 a时间长度控制试验积分结果的分析与检验表明,区域气候模式由于具有较高的分辨率和较完善的物理过程,它对中国区域地面气温和降水的模拟效果较全球模式有了较大提高,如它模拟的各月气温与实况的相关系数全年12个月的平均由全球模式的0.83提高到0.92,降水由0.48提高到0.65。

Impacts of greenhouse effects (2 × CO2) on climate change over China as simulated by a regional climate model have been investigated. The model was based on RegCM2 and is nested in one- way mode within a global coupled atmosphere - ocean model (CSIRO R21L9 AOGCM). Two multi - year simulations, the control run with normal CC>2 concentration and sensitive run with doubled CO2 concentration are conducted. As Part I of the publications, results of control run of the CSIRO, i.e. its simulations of present climate in China, are analyzed briefly. It shows that the model has a certain ability in the simulations of surface air temperature and precipitation over China. Therefore, its results can be used as initial and boundary conditions to drive the regional model. Analysis of control run of RegCM2 shows that with a high resolution, the model improves the simulations of surface air temperature and precipitation in China compared to the CSIRO model, especially for the precipitation. The spatial correlation coefficient between simulated and observed annual temperature increased from 0.83 in the CSIRO to 0.92 in the RegCM2 and for annual precipitation from 0.48 in the CSIRO to 0. 65 in the RegCM2. A similar improvement in the RegCM2 compared to the CSIRO was found in all simulated months. The main improvement for surface temperature is that RegCM2 can simulate the fine scale structure of temperature caused by topography. RegCM2 greatly improved the spatial distribution of precipitation by eliminating the virtual precipitation center in mid - west China, which was simulated by many other GCMs. The precipitation simulated by RegCM2 in north and northwest part of China is smaller than that by CSIRO which makes it closer to the observation. It suggests that with the good performances of climate simulations, RegCM2 can be widely used in the regional climate study of China, e.g. climate change scenario simulations.