赤道中东太平洋海温和北极海冰与夏季长江流域旱涝的相关

夏季长江流域旱涝形成不仅归因于大尺度夏季风环流(包括西太平洋副高)系统和热带海温的异常,而且极地热汇作用造成的冷空气活动异常也必须同时引起注意。事实上,许多研究已经表明,El Nino(或La Nina)事件和夏季长江流域旱涝关系并不简单,例如,El Nino年常对应于干旱,但是La Nina年长江流域夏季也可能干旱。显然,试图用海温这一单因子来解释旱涝成因存在着明显的因难。 就大气环流异常而言,近年来的一些研究已经指出和热带热源相对应的高纬热汇(如极冰)异常对大气环流的作用和热带海温同等重要,观测分析和数值模拟结果均表明:赤道海温和北极海冰任何—方的变动均可以引起大气环流显著的响应,大气环流形成和异常变化根本上取决于赤道和极地之间的热力差异。

CORRELATIONS BETWEEN DROUGHT/FLOOD IN YANGTSE RIVER VALLEY AND ANOMALIES OF CENTRAL-EASTERN EQUATORIAL PACIFIC SST AND ARCTIC SEA ICE EXTENT

Correlations between the drought/flood in the Yangtse River valley and anomalies of central-eastern equatorial Pacific sea surface temperature (CEPSST) and Arctic sea ice extent are examined by using observational data. The leading results show that,the drought and/or flood in June is noticeably associated with the anomalies of CEPSST in April-June and Arctic sea ice extent over the northern Pacific in January-March, but the drought/flood in July only with anomalies of Arctic sea ice extent over the northern tlantic rather than with those of CEPSST. Therefore, it may come to a conclusion that polar sea ice is also an important factor inducing the short-term climatic changes in comparison with the equatorial SST.