基于CMIP5资料的热带太平洋和印度洋海温变化与降水变化的关系及其成因分析

Relationship between sea surface temperature variation and precipitation variation over tropical Pacific and Indian Ocean and its cause analysis based on CMIP5 data

利用第五次耦合模式比较计划(Coupled Model Intercomparison Project Phase 5,简称CMIP5)月平均资料,从季节变化角度,对热带太平洋、印度洋海温变化与降水变化的关系及其成因进行了初步分析。20个模式集合平均结果表明:在全球增暖背景下,热带太平洋年平均的海温变化与降水变化符合"warmer-get-wetter"型特征,而季节平均与年平均存在明显的差异;冬季和春季,海温增暖最大区和降水增加区之间存在东西向和南北向的位置偏差;夏季和秋季,二者只存在明显的南北位置偏差,且与冬季和春季的情况相反。热带印度洋的冬季和春季海温变化与降水变化也存在位置偏差。两个热带大洋季节平均的降水变化均是"warmer-get-wetter"和"wet-get-wetter"两个机制共同作用的结果。

Based on the monthly mean global data from CMIP5（ Coupled Model Intercomparison Project Phase 5）,this paper studies relationship between sea surface temperature（ SST） variation and precipitation variation over tropical Pacific and Indian Ocean along with its possible causes from the point of seasonal variation. The ensemble mean results of 20 models show that,under the background of global warming,annual spatial distributions of SST and precipitation variations over tropical Pacific Ocean accord with the＂warmer-get-wetter＂mechanism. However,the differences between seasonal mean and annual mean are obvious. Both zonal and meridional positional deviations between the local maximum enhanced SST and increased precipitation are detected in winter and spring,but only opposite meridional deviation is detected in summer and autumn. Meanwhile,the similar positional deviation between SST and precipitation exits over tropical Indian Ocean in winter and spring as well. Moreover,seasonal changes of precipitation over two tropical oceans accord with both the ＂warmer-get-wetter＂mechanism and the ＂wet-get-wetter＂mechanism.