COMPARATIVE ANALYSIS OF MOISTURE AND HELICITY DURING EXTRAORDINARY STORMS CAUSED BY TWO TYPHOONS IN DIFFERENT SEASONS
LU Xiao-dan
WANG Li-juan
LIU Guo-zhong
YAO Xue-min
Abstract：By using the dataset of CM A-STI Tropical Cyclone Optimal Tracks,the NCEP/NCAR reanalysis data,Guangxi regional automatic weather stations observation data and precipitation data provided by China Meteorological Data Sharing Service,typhoons Haiyan(1330) and Ramasun(1409),which caused extraordinary rainstorms in Guangxi,were analyzed.The results showed that the cold air effect was obvious on the late-autumn typhoon Haiyan,while the summer typhoon Ramasun was influenced by the southwest monsoon.Due to the southwest monsoon,the transfer of water vapor was stronger with Ramasun,which affected Guangxi,than with Haiyan,and the water vapor transfer of Haiyan was totally dependent on its circulation.On the contrary,in terms of dynamic conditions,Haiyan was stronger than Ramasun,its maximum value of the helicity center was also greater,and its moisture convergence layers were thicker over Guangxi.The rains beginning in the eastern boundary of Guangxi started to decrease after reaching the maximum input,and the transfer of water vapor from output transformed into input and began to increase suddenly,while the strongest periods of rainfall occurred around the time when the water vapor input of the southern boundary peaked.The positive helicity center had good corresponding relationship with the heavy rainfall area and were at least six hours in advance,so that the helicity can be used as an important reference factor in forecasting torrential rain caused by typhoons.
Keywords：extraordinary stormcold airsouthwest monsoontransfer of water vapormoisture budgethelicity
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：11( 375-385 )