全球变暖对中国区域积雪变化影响的数值模拟

Simulation of the Changes in Snow Cover over China under Global Warming by a High Resolution RCM

对20km高水平分辨率区域气候模式(RegCM3)所模拟的全球变暖背景下,中国区域未来积雪变化进行了分析.检验了模式对当代(1961-1990年)积雪日数、积雪量、积雪开始和结束时间的模拟,结果表明:与观测相比,模式对这些变量均有较好的模拟能力,但模拟的积雪日数和积雪量偏多,积雪开始时间偏早,结束日期偏晚.21世纪末(2071-2100年)在IPCC SRES A2温室气体排放情景下,中国大部分地区积雪日数和积雪量将减少;积雪开始时间推后,结束时间提前,但在各个地区表现也有所不同,并在个别地区出现相反的变化.将中国区域分为东北、西北、青藏高原3个分区,结果显示:各分区平均积雪量均为减少,积雪开始时间推后,而积雪结束时间则都将提前,其中,青藏高原地区的变化最为显著.

Based on the multi-decadal climate change simulations conducted by a high resolution regional climate model （RegCM3） at 20 km grid spacing,changes in snow cover under global warming are analyzed. Validation of the model performance in simulating snow cover days,snow amount,snow cover starting and ending dates during 1961-1990 are firstly carried out. Results show that the distributions of these variables are well reproduced by the model as compared to observation. The model overestimated the snow cover days and snow amount,while an earlier starting date and delayed ending date of snow cover were simulated. Under the IPCC SRES A2 emission scenario in the end of the 21st century （2071-2100）,less snow cover days and less snow amount,together with postponed starting date and advanced ending date of snow cover are simulated in general over China. This is reflected in the area-mean values over the three major sub-regions：Northeast China,Northwest China,and the Tibetan Plateau,where the snow cover is the deepest. The changes in the Tibetan Plateau are of the most pronounced among the three. While the amount of the changes show differences across different areas. It is also noted that change in the direction opposite to the above is also found in some places.