西北太平洋热带气旋群发与MJO的联系

On the Relationship between MJO and Clustering of Tropical Cyclone Activities over the Western North Pacific

利用客观MJO指数及定义西北太平洋热带气旋(TC)群发标准,初步研究了西北太平洋TC群发特征及其与MJO的相互作用,结果表明:(1)30°N以南的西北太平洋海域平均每年发生3.6次TC群发过程,在1978—2009年间TC群发呈现出减少的变化趋势,但群发强度无明显变化;(2)当MJO强对流位于印尼群岛东部(即位相5)和西太平洋东部(即位相7)时西北太平洋TC最易群发;而当MJO对流主要位于非洲(即位相1)和印度洋西部时(即位相2)时,TC群发受到抑制;(3)TC群发活动后MJO的传播发生变化,这种变化与TC群发活动本身及其引起的海气相互作用通量的改变有关。

By using the object MJO index and defining the clustering of tropical cyclone (TC) activities over the Western North Pacific (WNP), the clustering characteristics of tropical cyclones and their associations with MJO are discussed. The results show that 1) the frequency of the clustering of TCs is 3.6 per year in the south of 30°N over the WNP. There was a decreasing trend of the frequency of the clustering TC activities during 1978 to 2009, while there was not any trend of the intensity. 2) The clustering of TC activities favor occurring in MJO phase 5 and 7, when the strong MJO convection locates in the east of Indonesia and the east of western Pacific, while they seldom occur in MJO phase 1 and 2, when the strong MJO convection locates in Africa and the west of Indian Ocean.3) The characteristics of MJO propagation change after the clustering TC activities, such changes may possibly be related to the cluster activities themselves and the changes of the air-sea variables which they have brought about.