Abstract:Total and extreme precipitation in Hainan Island was investigated in this study, based on consistent meteorological data for the period . Results show that tropical cyclones mainly impact Hainan Island between June and November, during which time they account for more than one-third of the total precipitation. Over the past four decades, the number of TCs impacting Hainan Island has significantly decreased. Correspondingly, the TC precipitation and its contribution to the total precipitation have slightly reduced. Extreme rainfall events because of cyclones are responsible for nearly 60% of Hainan's overall 'daily extreme precipitation' and 23% of Hainan's total precipitation. Noticeably, the number of extreme heavy precipitation days and total amount of precipitation from those extreme events influenced by TCs has increased. On average, the precipitation amount and the number of days of extreme events caused by each cyclone have been significantly increased.
With the typhoon cyclone data, NCEP/NCAR reanalysis datasets and PDO index data from 1949 to 2018, the characteristics of violent typhoon events seriously affecting Hainan Island (VTESAHs for short) in the past 70 years are analyzed. On this basis, the characteristics of VTESAHs in the different phases of PDO and their relationship with SST are analyzed. The results show that there is obvious inter-annual variation in the frequency of VTESAHs. The VTESAHs have good continuity in both calm and active periods, and have obvious clustering. VTESAHs are more likely to occur in the cold phase years of PDO, almost generated in the western Pacific. The source of VTESAHs in the cold phase years of PDO are mainly concentrated in the sea area of 5 °N -15°N and 125 °E -150°E, while the source of VTESAHs in the warm phase years of PDO are mainly around 10°N. When the PDO phase is cold (warm), there is a significant negative (positive) correlation between the frequency of VTESAHs and the sea surface temperature in the western Pacific Ocean east of the Philippines at low latitudes.
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