THE RELATIONSHIP BETWEEN THE OFFSHORE INTENSIFICATION OF SUPER TYPHOON RAMMASUN AND LOW-FREQUENCY VAPOR TRANSPORTATION AND ITS PRECEDENT SIGNAL
WEI Xiao-wen
WU Kun-di
CHEN Ming
WU Hui
LI Xin-hao
Abstract：Using NCEP/NCAR reanalysis data and tropical cyclone yearbooks compiled by Shanghai Typhoon Institute of CMA,we analyzed the variation characteristics of vapor transportation when the super typhoon Rammasun intensified in the South China Sea (SCS),mainly discussed the effect of 10 ～30 d low-frequency vapor transportation on Rammasun intensification,and identified the precedent low-frequency signal of typhoon variation from low-frequency circulation field:(1) Rammasun has two main vapor transportation channels,one in the Bay of Bengal (BOB) and the other in the SCS,and the intensity of the BOB channel is greater than that of the SCS channel;(2) The offshore intensification of Rammasun has close relationship with 10～30 d low-frequency vapor transportation.Under the effect of tropical low-frequency system,low-frequency west vapor transported from the BOB channel and southward transported vapor from the SCS channel converge over the SCS,providing favorable conditions for the intensification of Rammasun;(3) For the typhoons landing on the east of Hainan Island,their landing intensity has significantly negative correlation with low-frequency vapor transportation from the BOB channel,and relatively weak negative correlation with the vapor transportation from the SCS channel 5～7 d in advance.If the low-frequency vapor transportation flux inflowing from the cross sections of the two channel is at the low-value phase of the low-frequency oscillation,it is good for the typhoon to intensify over the SCS 5～7 d later,otherwise weakening.
Keywords：typhoon Rammasunvapor transportationlow-frequency oscillation10～30 dprecedent signal
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：6( 267-272 )