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热带气旋快速增强区域气候漂移及成因初步分析

Analysis on the cause of climatic drift of tropical cyclone rapid intensification area

  • 摘要: 利用中国气象局上海台风研究所(CMA-STI)1949-2015年热带气旋(TC)最佳路径数据集和NCEP/NCAR再分析资料,对西北太平洋(含南海海域)1949-2015年TC快速增强(RI)集中区位置变化和影响因素等进行统计分析。结果表明:(1)RI的发生频数及伴有RI发生的TC频数均呈减少趋势,RI持续时间占TC生命史的比例及伴有RI发生的TC占TC总频数的比例呈震荡减小趋势。(2)RI集中区北界南移、南界北移,总体收缩南移,东界西移、西界东移,总体收缩西移。(3)西北太平洋环境风垂直切变(VWS)的弱切变区向西向南的气候漂移和海表面温度正距平区域的向南扩展是导致发生RI的TC最北纬度显著向南漂移的可能原因,发生RI的TC最南纬度向北的漂移则可能与高海表面温度(SST)向北扩展密切相关。(4)RI集中区的200 hPa高空辐散变强、850 hPa水汽输送加强等有利环境场条件的叠加,也对RI集中区的气候漂移有重要影响。

     

    Abstract: Based on the tropical cyclone data from Shanghai Typhoon Institute of China Meteorological Administration (CMA-STI) and the NCEP reanalysis monthly data for the period of 1949-2015, the influence of climatic drift of rapid intensification (RI) concentrated area in tropical cyclone (TC) activity in the Northwestern Pacific Ocean has been analyzed statistically. The results are shown as follows. (1) The frequencies of RI process and TC with RI process occurring both declined gradually. Additionally, the proportions of RI process duration to TC lifetime and TC with RI process occurring to total TC decreased. (2) The northernmost edge moved southward, the southernmost edge moved northward and the whole RI concentrated area moved northward and shrunk. The westernmost edge moved eastward, the easternmost edge moved westward and the whole RI concentrated area moved westward and shrunk. (3) The domain of weak vertical wind shear drifted westward and southward, and the domain of positive anomalies of sea surface temperature (SST) extended southward. These are the two possible reasons for the southward movement of the northernmost latitudes when RI process occurs in TC activity in the Northwestern Pacific Ocean. Meanwhile, the northward movement of southernmost latitudes may be closely related to the northward expansion of the high SST. (4) The combined effects from both the enhanced air divergence at 200 hPa and the intensive transport of water vapor at 850 hPa in the concentrated area also have significant influence on the climate drift in RI concentrated area.

     

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