作　　者： ; ; ;

机构地区： 广州市气象局

出　　处： 《大气科学》 2008年第2期335-344,共10页

摘　　要： 基于美国NOAA在ENSO诊断分析中使用的海洋Nino指数（Oceanic Nino Index,简称ONI）,将1950～2005年冬季分成强El Nino、强La Nina、弱El Nino、弱La Nina和没有发生ENSO事件5类,用分类合成方法研究了冬季东亚大气环流对ENSO事件的响应。结果表明,在低纬度,大气环流对ENSO事件的响应具有较明显的准线性特征,即大气对海洋暖事件与冷事件的响应大致是反位相的,对弱ENSO事件的响应与强ENSO事件相似但强度较弱。中高纬度大气环流与ENSO事件也有一定的联系,但同等强度暖事件与冷事件下大气环流距平场上的系统分布没有呈现明显的反位相,表明大气对海温异常的响应是复杂的。强El Nino事件时大气的响应信号显著,主要表现在东亚中高纬西风气流增强,亚洲北部地区气温偏高,距平风场上的切变线从长江中下游向东伸展,菲律宾海距平反气旋西北侧的偏南气流和南支槽前西南气流加强,其共同作用使南海和中国东南沿海出现显著的偏南风距平;强La Nina事件时,长江中下游向东伸展的脊线不明显,中国南方至南海处于偏北风距平区,但通过统计检验的范围减小;弱El Nino事件时,菲律宾海距平反气旋西北侧的西南气流偏东,与南支槽前西南气流分开,使得华南和南海的偏南风距平没有强El Nino时显著;弱La Nina事件时,西风带纬向气流减弱,亚洲北部地区气温偏低。对ONI指数与亚洲北部温度指数（NTI）的散点图的分析显示,9个强El Nino冬季中有8年亚洲北部温度距平偏高,7个弱El Nino冬季中只有1年温度偏高;8个强La Nina冬季有4年温度偏低,12个弱La Nina冬季中有11年温度偏低;亚洲强暖冬和强冷冬的发生与ENSO事件的联系不紧密。 The ENSO phenomenon, which is known to be the most prominent signal in air- sea interactions, plays an important role in the interannual variability of East Asian winter monsoon. In this paper, the responses of East Asian winter monsoon to ENSO events are analyzed using the composite method based on the Oceanic Nino Index （ONI） and NCEP/NCAR reanalysis data with classification of the winters from 1950 - 2005 into 5 categories of strong E1 Nifio, strong La Nina, weak El Nino, weak La Nina and non-ENSO event. The results show that response of the East Asian circulation in low latitudes to ENSO events has quasi-linear characteristics, i.e. response of the tropical atmosphere to the warm events is reverse to that of cold events, and that to weak ENSO events is similar to strong ENSO events except for weakened intensity. However, distribution of circulation anomalies in middle and high latitudes does not show obvious phase reversal for warm and cold ENSO events, indicating that response of the atmosphere to SST anomaly is complex. The signals of significant response of the extratropical atmosphere to strong El Nino events are represented mainly by enhancement of the westerly flow in middle and high latitudes in East Asia, positive anomalous temperature in northern Asia, eastward extension of anomalous wind shear in the middle and lower reaches of the Yangtze River. The anomalous Philippine Sea anticyclone, working together with intensified trough in south branch of westerlies, is favorable for the southerly flow in the South China Sea and along the southeast coast of China. But, during the strong La Nina events, the ridge in the middle and lower reaches of the Yangtze River is not evident, and the southern part of China and the South China Sea are covered by northerly anomaly, with shrinked area that passes significance test. Under weak El Nino events, the southwesterly flow in the northwest of the anticyclonic anomaly in the Philippine Sea is shifted eastward, and separated with southwesterly flow ahead of the tr

关 键 词： 冬季风 事件 统计分析

领　　域： [天文地球]