西北太平洋热带气旋在ENSO发展和衰减年的路径变化

本文运用有限混合模型算法对1979~2015年夏、秋季（6~11月）中国气象局（CMA）上海台风研究所（STI）的最佳路径数据集热带气旋（TC）路径进行聚类，将其路径分为七类，分别为第一类（西太西移型）、第二类（南海西移型）、第三类（沿海转折型）、第四类（低纬转折型）、第五类（洋面转折型）、第六类（近海转折型）、第七类（日本海转折型）；并利用S-EOF（季节EOF，Seasonal Empirical Orthogonal Function）方法确定ENSO四个位相（El Ni?o发展年、El Ni?o衰减年、La Ni?a发展年、La Ni?a衰减年），分析在不同ENSO位相下TC路径的年际变化以及相应的流场，得到一些有意义的结论:El Ni?o发展年，TC在西北太平洋东南海域活动频繁，以第六类（近海转折型）路径为主；El Ni?o衰减年以第二类（南海西移型）路径居多，第七类（日本海转折型）路径也较为活跃；La Ni?a发展年，TC集中在西北象限海域，以第七类（日本海转折型）路径为主；La Ni?a衰减年，TC源地多位于我国沿海地区与台湾岛附近洋面上，以第三类（沿海转折型）路径为主。

Variation of Tropical Cyclone Track in the Western North Pacific during ENSO Developing and Decaying Years

This paper aims to further explore the influence of various ENSO (El Niño-Southern Oscillation) phases on the tropical cyclone (TC) track over the western North Pacific (WNP). Based on the best-track TC data for the period 1979-2015 from the Shanghai Typhoon Institute (STI) of China Meteorological Administration (CMA), the present study applies the Finite Mixed Model algorithm to cluster the TC tracks. TC tracks from the best-track 1979-2015 dataset are classified into seven distinct clusters, i.e., Cluster-1 (WNP westward cluster), Cluster-2 (South China Sea westward cluster), Cluster-3 (coastal recurving cluster), Cluster-4 (low latitude recurving cluster), Cluster-5 (ocean recurving cluster), Cluster-6 (offshore recurving cluster) and Cluster-7 (Japan Sea recurving cluster). Besides, the four phases (El Niño developing years, El Niño decaying, La Niña developing years and La Niña decaying year) of ENSO are determined by S-EOF (Seasonal-Empirical Orthogonal Function) method. After that, the study analyzes the impacts of different ENSO phases on TC activities and circulation situations. The results show that Cluster-6 is the main path in El Niño developing years and TCs are active in the southeastern quadrant of the WNP. Cluster-2 and Cluster-7 are the two major tracks in El Niño decaying years. In La Niña developing years, TCs are active over the western part of the WNP and Cluster-7 accounts for most of the TC tracks. In La Niña decaying years, TCs are active over the southwestern quadrant of the WNP and Cluster-3 is the major TC path.