人类活动排放的CO_2及气溶胶对20世纪70年代末中国东部夏季降水年代际转折的影响  

Effects of anthropogenic emissions of CO_2 and aerosols on decadal transition of summer precipitation over eastern China in the late 1970s

作　　者：王欢 李栋梁 WANG Huan;LI Dongliang

机构地区：[1]南京信息工程大学大气科学学院/气象灾害预报预警与评估协同创新中心/气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室,南京210044

出　　处：《气象学报》2019年第2期327-345,共19页Acta Meteorologica Sinica

基　　金：国家重点基础研究发展计划(973计划)项目(2013CB430202);公益性行业(气象)科研专项(GYHY201506001-1);国家自然科学基金项目(41305080;91337109);江苏省普通高校学术学位研究生科研创新计划项目(1354051401003);江苏高校优势学科建设工程项目(PAPD)

摘　　要：全球变暖背景下,中国东部夏季降水在20世纪70年代末开始较19世纪呈现东北及长江中、下游地区多雨,华北及华南少雨的特征。与此同时,人类活动排放的CO_2及气溶胶量也发生了明显的年代际变化。文中利用地球系统耦合模式(CESM)诊断了中国东部夏季的水分收支对人类活动排放的CO_2及气溶胶年代际变化的响应。发现CO_2排放量增加后,江淮流域的水汽辐合以及中国南方的水汽辐散主要是与质量辐散有关的动力项及与湿度梯度相关的热力项共同作用的结果,但动力作用更显著。气溶胶效应则主要通过动力作用使得江淮流域水汽辐合,而中国南方地区水汽辐散。虽然CO2和气溶胶对辐射量及温度的影响差别很大,但通过改变温度梯度,热成风效应产生的动力作用都会导致江淮流域上升运动增强,降水增多;而中国南方下沉运动显著,降水减少,与观测结果一致,且CO2相较于气溶胶的影响更为显著,证实了20世纪70年代末人类活动对中国东部夏季降水年代际转折的影响。In the background of global warming, summer precipitation over eastern China(ECSP) experienced a significant decadal change at the end of the 1970 s with positive rainfall anomalies over northeastern China and the middle and lower reaches of the Yangtze River and negative rainfall anomalies over northern and southern China. We examined anthropogenic emissions of CO2 and aerosols which had discernible decadal transitions around the mid to late 1970 s and contributed to the ECSP change, and elucidated the underlying mechanism. Moisture budget over eastern China was calculated using the Community Earth System Model(CESM). The water vapor convergence over the Yangtze-Huai River valley and moisture divergence over southern China in the CO2 simulation are dominated by the combined effects of the dynamic contribution related to mass divergence and the thermodynamic contribution related to moisture gradients, which have greater effect on the ECSP than that of aerosols. Aerosols forcing contributed to the rainfall increase over the Yangtze-Huai River valley and decrease over southern China primarily by the dynamic effect. The enhanced upward and downward motions caused by changes in temperature gradient led to similar rainfall anomalies over eastern China under the effects of CO2 and aerosols, although their impacts on radiation and temperature were different. These results confirm that CO2 and aerosols did have some effect on the decadal transition of ECSP at the end of the 1970 s.

关 键 词：中国东部夏季降水 年代际转折 人类活动 地球系统耦合模式 水分收支 

分 类 号：P426.6[天文地球—大气科学及气象学]