中国干湿变化的高分辨率区域气候模式预估

Dry/Wet Climate Projections over China Using a High-Resolution Regional Climate Model

本文使用三个全球气候模式驱动下的高分辨率区域气候模式RegCM4的试验数据,首先评估了RegCM4对参考时段(1986~2005年)中国干燥度指数(AI)的模拟能力,而后根据典型浓度路径中等排放(RCP4.5)情景下RegCM4试验对中国未来干湿变化进行了预估研究。结果表明,RegCM4能够合理模拟中国区域AI的空间分布。两种潜在蒸散发计算方法得到的参考时段AI在空间分布和数值上存在一定差异,尤其是在中国西部高海拔地区和北方地区。在三个全球气候模式驱动场作用下的RegCM4预估试验中,21世纪中期(2046~2065年)和末期(2081~2098年)中国区域平均AI较参考时段分别减小2%~4%和2%~5%,其中西北中部变湿,其他地区均变干。不同地区未来干湿变化的主要影响因素存在差异,西北中部降水变化为主导因素,其他地区主要受控于升温所引起的潜在蒸散发变化。

We evaluate the ability of models to simulate the aridity index(AI) and project the dry/wet climate changes in China under ther epresentative concentration pathway(RCP) 4.5 scenario using experimental data of a high-resolution regional climate model(RegCM4) nested within three global climate models. For the reference period of 1986–2005,RegCM4 can reasonably simulate the spatial pattern of AI in China, and the results of the simulated AI slightly differ between the two methods for calculating potential evapotranspiration, especially in the western high-altitude and northern regions over the country. Based on the projections of RegCM4, the AI averaged over China would decrease by 2%–4%and 2%–5% in the middle(2046–2065) and end(2081–2098) of the 21 st century relative to the reference period,respectively, with central Northwest China becoming wetter and other regions becoming drier. The predominant factor influencing the future dry/wet climate changes in China varies with regions. Precipitation is the leading factor in central Northwest China, while in the other regions, temperature increase plays the dominant role via potential evapotranspiration changes.