Studies On The Problems About Typhoon Landfall And Variation Of Typhoon Intensity

By using data in the period of 1949-2000, climatic characteristics of tropical cyclones over western North Pacific in the latest 50 years are investigated. The results show that there exists a descent trend in tropical cyclone(TC) frequency over western North Pacific and landfall TC frequency in China, Southern China and Eastern China in recent 50 years, and the trend becomes significant in the latest 10 years.Chen et al noted that there are three kinds of landfall typhoon tracks; subtropical high and polar front, whose evolutions and adjustments may modify typhoon movement, are the main synoptic systems which influence the track of landfall typhoon. Based on the data in the period of 1991-2000, typhoon tracks which landfall the coastal of East Sea and their corresponding circulation patterns are investigated. The results verify that the Chen's theory above still comes into existence in 1990s.Secondly, by performing eight experiments with a high resolution barotropic model, which is integrated for 36 hours, the interaction between a mesoscale vortex and a typhoon vortex is investigated. The relationship between the spatial scale dimensions of the initial mesoscale vortex and the variation of typhoon intensity is also discussed. The results show that the interaction can intensify the maximum tangential velocity of typhoon under the condition of certain parameter ranges. The value is 4.0m/s, which is more reasonable than that of Moller et al (1999).