Overview and Genesis Analysis of the Intense Tropical Cyclone IDAI in the South-West Indian Ocean

In this paper, the NCEP reanalysis data and the sea surface temperature data are used to diagnose the development process of the intense tropical cyclone “IDAI” generated in the SouthWest Indian Ocean. The results show that the presence of the high pressure ridge in the northeast and the weak high pressure in the south makes “IDAI” moving slowly or even stagnantly. According to the intensity, the development of “IDAI” can be divided into three processes: the rapid strengthening process, the weakening maintenance process and the secondary strengthening process. Then it eventually developed into an intense tropical cyclone. The high sea temperature, the relatively small vertical wind shear and the favorable high-level divergence conditions are benifit environmental conditions for its rapid strengthening; during its development process, the external water vapor transport is weak, the water vapor and heat mainly come from the ocean; the eye wall replacement process causes the second strengthening of its intensity. Finally it landed in Mozambique with an intensity of intense tropical cyclone. Keyword—South-West Indian Ocean, Tropical cyclone, Genesis analysis 摘要—本文利用 NCEP 再分析资料、海温资料等对西南印度洋 生成的强热带气旋 “伊代”(Idai)的发展过程进行了诊断 分析,结果表明:其东北侧的高压脊及西南侧弱高压的存在 使得“伊代”移动缓慢甚至停滞不前;“伊代”经历了快速 加强阶段、减弱维持阶段以及二次加强阶段,最终发展成为 强热带气旋,较高的海温、相对较小的垂直风切变以及良好 的高层辐散条件是其发展加强的有利环境条件,使其强度能 够迅速发展;其发展过程中外部水汽输送较弱,水汽和热量 主要来自海洋;眼墙置换过程促使其强度二次爆发,最终以 强热带气旋级登陆莫桑比克。