IPCC AR4气候模式对长江流域气温和降水的模拟性能评估及未来情景预估

EVALUATION OF THE SIMULATION PERFORMANCE AND SCENARIO ANALYSIS FOR TEMPERATURE AND PRECIPITATION BY IPCC AR4 GLOBAL CLIMATE MODELS ON YANGTZE RIVER BASIN

利用政府间气候变化专门委员会第四次评估报告的22个新一代全球气候模式基准期(1961～1990年)模拟结果,从时空尺度分别讨论了与观测过程的差异,评估了模式对长江流域气温和降水的模拟性能。结果表明22个气候模式对长江流域具有一定的模拟能力,地面气温的模拟值都偏低,部分降水的模拟值局部偏高。不同的气候模式的模拟能力差异显著,大部分模式对长江流域的模拟精度有待进一步改进,只有少数几个模式(降水有6个模式,气温有5个模式)的年变化趋势与实况基本一致。综合比较,UKMO_HadCM3和NCAR_PCM两个模式基本能再现长江流域降水和气温的年变化特征。长江流域降水和气温未来情景预估表明各个模式和情景结果虽然存在差异,但对未来90年气候变化的模拟趋势基本一致,将持续增温、降水出现区域性增加,并着重讨论了UKMO_HadCM3模式在2020s(2010～2039年)、2050s(2040～2069年)和2080s(2070～2099年)3个时段的降水和气温时空变化特征,研究结果表明3个时段气温和降水在不同情景下都是逐渐增加的,A2情景下未来降水增幅最显著,B1情景增幅最小。

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change（ IPCC AR4）presents twenty- two global climate models （GCMs）. In this paper, we evaluate the performance of the 22 GCMs in simulating temperature and precipitation over the Yangtze River Basin by comparing with ground observations for 1961 - 1990. The results suggest that all the GCMs underestimate surface air temperature and some models overestimate precipitation in most regions in the Yangtze River Basin. Only a few models （6 models for precipitation and 5 models for temperature）show roughly consistent with the observations in annual temperature and precipitation variations. Comparatively, UKMO_HadCM3 and NCAR_PCM are able to better reproduce the observed annual temperature and precipitation variability over the Yangtze River Basin. Although the scenarios predicted by the GCMs vary greatly, all the models predict consistent increasing trends in temperature and precipitation in most regions in the Yangtze River Basin in the next 90 years. The paper emphasizes the predictions of UKMO_HadCM3 for temperature and precipitation in 2020s （ 2010 - 2039 ）, 2050s （ 2040 - 2069 ） and 2080s （ 2070 - 2099 ）. The results suggest that the temperature and precipitation will both increase in all three periods under different scenarios,with scenario A1 increasing the most and scenario B1 the smallest.