Study On The Characteristics Of Typhoon In The Western Pacific In Recent Hundred Years And Its Attribution To Air-Sea System And Factors

In order to exploit changes and causes of tropical cyclone activity in the Northwest Pacific on a centennial scale.Tropical cyclone is one of the major meteorological disasters affecting the world.It is often accompanied by strong winds and rainstorms,which has a serious impact on the coastal areas of the Western Pacific.It has been the focus of research for a long time.Previous studies have shown that the subtropical high and sea surface temperature have an important impact on tropical cyclones in the Western Pacific.However,the relationship between the activity changes of typhoons on a hundred years scale and these physical quantities has not been fully studied.The research focuses on the changes of typhoon activities on a hundred-year scale,combines the changes of typhoon activities with subtropical high,radiation flux,Western Pacific warm pool and ENSO,studies the relationship between the changes of typhoon activities in the Northwest Pacific on a hundred-year scale and these systems,then studies the change law and causes of typhoon activities on a long-term scale.The TC’s data used in the study are from the best international climate management file IBTRACS,and the data of flow field,sea surface temperature,pressure field and radiation flux are from the CMIP6 and NOAA 20 th century dataset.The research focuses on the typhoon activities in the Northwest Pacific since 1884,through EOF analysis,wavelet analysis,significance hypothesis test,correlation analysis,causality analysis and other methods are used to analyze the impact of large-scale system changes on Typhoon activities in the past century.The conclusions are as follows:(1)The intensity of the Western Pacific subtropical high is significantly positively correlated with the intensity of the sinking part of Hadley circulation and negatively correlated with the intensity of the rising part of Walker circulation.Since1860,the West Pacific subtropical high has a trend of increasing fluctuation,especially after 1980.This condition is conducive to the expansion of typhoon activity’s area westward and northward,thus increasing the probability of typhoon affecting in China.(2)The change of intensity and range of the Western Pacific warm pool caused by the change of radiation flux is conducive to the strengthening of typhoon.(3)There are generally causal relationships between radiation flux and ENSO related variables.Some of these relationships are directly caused and some are indirectly related.The interaction between these fields can further affect the activities of typhoons.