The Research on Abnormal Features and Formation Causes of Tropical Cyclones Landing Southeastern Coastal Zone in 2005

Abstract

AbstractUsing 1949~2005 data from the Tropical Cyclone (Typhoon) Year‐Book of CMA, this paper investigates the features of the TC (tropical cyclone) activities in the western Pacific as well as TCs landing on the coastal areas of southeastern China, indicating that the numbers have dropped slightly, while the intensity of the landing TCs increased significantly. In 2005, the number of TCs of the western Pacific origin was fewer than normal but the landing typhoons were greatly stronger than the mean. Analysis of the abnormal phenomena resulting from the large‐scale circulation background shows that prior to the generation, the south‐Asian high (SAH) and the western Pacific subtropical high (sub‐high) are stronger than the mean, together with the weaker sub‐high and East Asian summer monsoon, vertical shear of zonal wind etc. in the TC season all working together prevent TCs from formation. On the other hand, the onland TCs are stronger than normal, which may be the result of abnormal vapor transport in the west part of the western Pacific, weak vertical wind shear, SSTA and the interaction between weather systems at mid‐ and low‐ latitudes.