摘要
利用ＡｔｕｏｎａＭａｒｑｕｅｓａｓＩｓ（９．４８°Ｓ，１３９．２°Ｗ）站对流层最大西风层（１５０ｈＰａ）和最大东风层（８５０ｈＰａ）纬向风异常值的差值，构造了赤道中、东太平洋Ｗａｌｋｅｒ环流强度指数Ｉｄ。并对Ｉｄ、平流层下部ＱＢＯ西风位相的长度和起始季节与ＥＮＳＯ事件的联系进行了研究。分析发现：Ｉｄ指数与南方涛动指数（ＳＯＩ）具有显著的正相关关系；Ｗａｌｋｅｒ环流圈在ＥｌＮｉｎｏ（ＬａＮｉｎａ）事件期间减速（加速）；ＥｌＮｉｎｏ事件前２０个月Ｗａｌｋｅｒ环流圈开始加速、上层西风加速早且稳定；强ＥｌＮｉｎｏ事件均出现在３０ｈＰａＱＢＯ西风位相持续期在５个季节以上，起始月在１１～１月（北半球冬季）的过程结束之后。从而进一步提出西风动量自平流层中部向下传播，诱发赤道中、东太平洋Ｗａｌｋｅｒ环流圈加速，导致海洋异变ＥＮＳＯ循环起始过程的“高层影响”
Constructed in the context of the difference in zonal wind anomaly (150 maximum westerly minus 850 hPa maximum easterly) over Atuona Marquesas Is. (9 48°S,139 2°W) is the equatorial central/eastern Pacific Walker circulation intensity index I d , alongside the study of the relation of I d and the length and starting season of lower stratospheric QBO westerly phase to an ENSO event. It turns out that I d is positively correlated, to high degree, with Southern Oscillation Index ( SOI ); the Walker circulation cell decelerates (accelerates) during the El Nio (La Nina) episode; the acceleration begins 20 months prior to the El Nio occurrence with upper westerly accelerated earlier and steadily; intense El Nio events happen when 30 hPa QBO westerly phase is maintained for more than 5 seasons and after the starting season (November to January, for northern winter) ends. Accordingly, we propose the “upper level influence” concept stating that westerly momentum propagates downward from the mid stratosphere, inducing the acceleration of the Walker circulation cell over the central/eastern Pacific equatorially, thus leading to the beginning of the SSTA related ENSO cycle.
出处
《南京气象学院学报》
CSCD
1996年第3期290-296,共7页
Journal of Nanjing Institute of Meteorology
基金
国家气象局<长期天气预报理论和方法>项目
关键词
赤道地区
环流
纬向风系
厄尔尼诺事件
equatorial region, Walker circulation, QBO westerly pahse, ENSO
