西北太平洋台风“海棠”结构的GPS下投式探空仪观测分析

Observational analysis of the structure of Typhoon Haitang (0505) over the western North Pacific by using the GPS Dropsonde data.

中文关键词:  台风“海棠”，下投式探空仪，台风结构，垂直风切变

英文关键词:Typhoon Haitang, Dropsonde, Structure of typhoon, Vertical wind shear

中文摘要:

      以0505号强台风“海棠”为例，利用“侵台台风之飞机侦察及下投式探空仪观测实验” (Dropsonde Observations for Typhoon Surveillance near the Taiwan Region, DOTSTAR)提供的高垂直分辨率GPS下投式探空仪（Dropsonde）观测资料，研究和比较了2次观测时段“海棠”的动力及热力结构差异，结果表明，第2次观测时的“海棠”在气旋式入流的强度和范围、高层暖区的强度和范围等方面均较第1次明显增强和扩大，且“海棠”环流的顶层发展出了一定强度和厚度的反气旋出流，加上“海棠”逐步移入高海温区和处于有利的弱垂直风切变环境中，“海棠”进一步增强；其次，用该观测资料对Frank等1999和2001年的数值模拟结果(垂直风切变通过激发热带气旋眼墙内部垂直运动的一波不对称结构而导致热带气旋结构的不对称分布)进行了验证。结果表明，观测分析结果与Frank等的数值模拟结果能较好地吻合，解释了环境垂直风切变对台风不对称结构的可能影响。

英文摘要:

      On the basis of the global positioning system (GPS) dropsondes data collected in the Dropsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR), the vertical kinetic and thermodynamic structures of the strong typhoon named Haitang (0505) over the western North Pacific are analyzed and compared for its different development stages. The results show that not only the kinetic structure but also the thermodynamic structure of Haitang’s is more robust in the second surveillance than the first surveillance, which is manifested by the stronger and larger scope of cyclonic inflow and the upper level warm core, as well as the developed anticyclonic outflow. Besides, Haitang was moving to the high SST region and situated in a favorable environment with weak vertical wind shear, and it therefore intensified during the second stage. The same data are also used to validate the published related numerical simulation results (Frank and Ritchie 1999， 2001), which show that the vertical wind shear can induce a wavenumber one asymmetry in the eyewall structure and has strong effect on the asymmetric structure of the tropical cyclone. The presented observational results are well consistent with their modeling results and explain how the vertical wind shear possibly produces a pronounced asymmetric structure in Haitang.