环境引导气流两类典型年际模态与西北太平洋热带气旋活动的联系

本文基于中国气象局上海台风研究所整编的热带气旋（Tropical Cyclone, TC）最佳路径资料及美国NCEP/NCAR月平均再分析资料，采用经验正交函数分解、合成分析、相关分析等统计方法，分析了1979-2016年7-9月西北太平洋地区海盆尺度大尺度环境引导气流的年际变化与热带气旋活动之间的联系。结果表明：（1）西北太平洋地区夏季大尺度环境引导气流在年际尺度上存在两个典型模态。其中第一典型模态大尺度环境引导气流呈现经向分布的偶极型环流型，该模态与东部型ENSO密切相关；第二典型模态大尺度环境引导气流呈明显的局地反气旋环流形态，其与中部型ENSO和热带大西洋海温异常紧密关联。（2）大尺度环境引导气流第一典型模态异常年份之间TC活动（生成位置、路径、强度和持续时间）具有显著差异，TC生成空间分布南北差异显著；TC路径尤其西北行和西行盛行路径也具有显著差异。（3）第二典型模态异常年份之间，TC生成位置和路径差异与第一模态呈现显著不同，TC生成位置呈现较为明显的东西向分布，在东南象限TC生成差异尤为显著，TC路径的差异主要体现在西北行和近海转向两类盛行路径。

Contents

Using the tropical cyclone (TC) best track data from the Shanghai Typhoon Research Institute of the China Meteorological Administration (CMA-STI) and the monthly mean reanalysis data of NCEP/NCAR, the interannual variability of the basin-scale large-scale environmental steering flow and the tropical cyclone activity in the western North Pacific (WNP) during peak season from July to September from 1979?2016 are investigated. The results show that: (1) There are two typical modes of summer large-scale environmental steering flow in the WNP at the inter-annual scale. The first typical mode is a dipole circulation with a meridional distribution, which is closely related to the eastern ENSO and the sea-air coupling mode in the WNP region. (2) The TC activity (generation location, tracks, intensity and duration) differs significantly between the two typical interannual mode anomaly years of the large-scale environment steering flow, but the differences have distinctly different characteristics for the two typical inter-annual modes. (3) The spatial distribution of TC generation location shows significant differences from north to south between the years of the first typical interannual mode anomalies of large-scale environment steering flow; the TC tracks, especially the northwestward and westward prevailing tracks, also have significant differences, and their average duration and intensity also show their corresponding significant differences. In the second major interannual mode anomaly years, the TC generation locations show significant east-west distribution especially in the southeast quadrant, and the differences in TC tracks are mainly in the northwestward and offshore steering prevailing tracks, and their mean durations and intensities also show significant differences.