FORMATION AND STRUCTURAL EVOLUTION OF INITIAL DISTURBANCE OF TYPHOON FUNG-WONG (2008)

• 来源期刊: 热带气象学报（英文版）
• 学科: 地球科学
• 年，卷（期）: 2016,（1）
• 页码范围: 1-10
• 页数: 10页
• 分类号: P444
• 语种: 英文
• DOI: 10.16555/j.1006-8775.2016.01.001

摘要

The formation of a tropical cyclone is the result of a process in which an initial disturbance evolves into a warm-core low-pressure system;however,the origin of the initial disturbance and the features of the initial fields are overlooked in most existing theories.In this study,based on FY-2C brightness temperature data and the Japan reanalysis dataset,the origin and evolution of the tropical disturbance that became Typhoon Fung-Wong (2008) were examined.The results demonstrated that the initial disturbance emerged within a saddle-type field with large vertical tropospheric wind shear.The vertical wind shear decreased with the adjustment of the upper circulation;moreover,accompanied by convection over the warm section around the upper cold vortex,it provided favorable thermal and dynamic conditions for the development of a tropical vortex.During its development,the zone of associated positive relative vorticity strengthened and descended from the mid-troposphere to lower levels.This rapid strengthening of lower-level vorticity was due to increasing convergence related to the intensification of the pressure gradient southwest of the subtropical high.This indicated that the upper cold vortex and West Pacific subtropical high played very important roles in this case.