亚洲冬夏季风对ENSO事件的响应

Response of the Asian Winter and Summer Monsoon to ENSO Events

根据ＮＣＥＰ／ＮＣＡＲ１９８０～１９９５年的再分析资料，分析了１９８０年以来５个ＥｌＮｉｎｏ和ＬａＮｉｎａ年冬、春和夏季２００、５００和８５０ｈＰａ合成高度场、风场、流函数场及温度场。发现在冬季ＥｌＮｉｎｏ（ＬａＮｉｎａ）年亚洲上空的环流型不利（有利）于寒潮向南爆发，导致亚洲冬季风和大洋洲夏季风弱（强）。在ＥｌＮｉｎｏ（ＬａＮｉｎａ）年冬季华南和青藏高原降水或降雪量为正（负）距平，这使得在晚春和初夏南亚的加热慢（快），导致夏季海陆的热力对比小（大），因而出现弱（强）夏季风。我们还发现强ＥｌＮｉｎｏ年冬季，在印度洋－亚洲上空出现类似于东太平洋－北美上空的ＰＮＡ遥相关，我们称之为印度洋－亚洲遥相关型（ＩＡ），引起亚洲冬夏季风年际变化的物理过程都是由ＩＡ遥相关型引起的。

Based on the monthly mean geopotential height, temperature and wind data at 200, 500 and 850 hPa level from the NCEP/NCAR reanalyze data sets for 1980～1995, the response of the Asian winter and summer monsoon to ENSO events is studied. By composing seasonal mean anomalies patterns for five El Nio (La Nia) years, it is found that during winter in El Nio (La Nia) years the follow pattern in East Asia is not favorable (favorable) for the outbreaks of cold air southward leading to weak (strong) winter monsoons; and that during winter in El Nio (La Nia) years there is above normal (below normal) precipitation in South China (including the Tibetan Plateau) leading to above normal (below normal) soil moisture content in there areas which could delay (quicken) and weaken (strengthen) the spring and summer heating of the land masses those results in weak (strong) summer monsoons. We also found that during winter in strong El Nio years there is a teleconnection pattern in Indian Ocean and Asia called IA pattern which is similar to PNA pattern in the eastern Pacific and North America. The IA pattern is responsible for the processes bring about interannual variability of Asian winter and summer monsoons.