THE CHARACTERISTICS OF TROPICAL CYCLONE INTENSITY CHANGE IN WESTERN NORTH PACIFIC

YANG Shi-qi; LI Ying; CHEN Lian-shou

doi:10.16032/j.issn.1004-4965.2017.05.010

Abstract：Based on the National Oceanic and Atmospheric Administration (NOAA) optimum interpolation sea surface temperature analysis data,European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis data and Joint Typhoon Waming Center (JTWC) best track data from 1984 to 2013,statistical methods are employed to analyze the intensity change of tropical cyclone (TC) in western North Pacific (100 °E～180 °,0～60 °N) and its relationship with environmental vertical wind shear (VWS),sea surface temperature (SST) and radius of maximum winds (RMW),especially for TC with rapid intensity change phenomenon.Results indicated that:(1) 35.2％ of the TC intensity stay neutral,and 52.8％ change slowly,while only 12.0％ come with rapid intensity changing,including rapid intensification (RI) and rapid weakening (RW).About 92.7％ of the RI phenomenon occur in typhoon (TY),strong typhoon (STY) and super Typhoon (SuperTY) intensity categories;(2) Since 2000,samples of neutral TC decrease,while those of RI increase,and the highest frequency mainly takes place in May,September and October;(3) TCs with VWS over 12 m/s have difficulty in intensifying or RI,except for the strong TCs;beyond Typhoon intensity category;(4) SST between 28.5～30 ℃ is favorable for TC intensifying and RI.While only strong TCs can still intensify rapidly with lower SST;(5) TCs tend to have a RMW smaller than 100 km.TCs with rapid changing intensity tend to be in 20～40 km RMW;(6) 24-hour variation of RMW is reduced for the intensifying TCs and enlarged for the weakening TCs,especially for TCs with RI.84.6％ of the RMW in SuperTY with RI phenomenon is reduced,but 15.4％ with the RI phenomenon is still enlarged.