穿过江苏热带气旋活动及潜在破坏力的时空分布特征

Temporal and spatial characteristics of activities and potential destructiveness associated with tropical cyclones crossing Jiangsu Province

  • 摘要: 资料和方法利用CMA-STI西北太平洋海域热带气旋(TC)最佳路径数据集,选取路径穿过江苏热带气旋,采用统计分析与合成分析等方法,目的揭示穿过江苏热带气旋活动及潜在破坏力的时空分布特征。结果结论结果表明,1949-2021年西北太平洋热带气旋中共有67个穿过江苏,占西北太平洋和登陆我国热带气旋总数的2.7%和10.2%,7月和8月生成频数最多、源地分布范围最广。从生成到进入江苏,穿过江苏热带气旋主要在6-10月登陆,8月登陆频次最多、登陆点南北跨度最大,登陆路线共14种,其中以登陆台湾后二次登陆福建再经陆上进入江苏的登陆路线占比最高。穿过江苏热带气旋四类路径的整体形态和穿过江苏时的运动方向与西北太平洋副热带高压西伸北抬程度密切相关。热带气旋主要在7-9月,从江苏东南部进入,从江苏东部沿海离开,西北太平洋副热带高压和季风环流等大尺度系统的季节性调整,使得热带气旋进入和离开江苏的位置随月份分别发生北上-南落和西进-东退的分布变化。江苏区域热带气旋路径频率总体上表现为由江苏东南部向西北方向减少的分布特征,热带气旋平均移动方向以偏北或北偏东为主,路径频率和移速矢量的空间分布存在明显的月变化特征。由于1949-2021年穿过江苏热带气旋的登陆强度和在江苏境内平均强度均显著增长,江苏区域热带气旋潜在破坏力(JS-PDI)存在显著上升趋势。JS-PDI存在明显月变化特征,其中8月JS-PDI明显高于其他月份。JS-PDI大值区主要分布于沿海区域和苏南东部,与江苏区域热带气旋平均强度大值区分布较为一致,同时JS-PDI大值中心与江苏区域路径频率大值中心存在较好的对应关系。

     

    Abstract: In this study 67 tropical cyclones (TCs) crossing Jiangsu Province are identified from a total of 2440 western North Pacific TCs during the 73-yr period of 1949-2021, using the best-track data archived at the China Meteorological Administration’s Shanghai Typhoon Institute (CMA STI). Temporal and spatial characteristics of activities and potential destructiveness associated with TCs crossing Jiangsu Province are investigated. Results show that TCs crossing Jiangsu Province, which mainly and widely generated in July and August, account for 2.7% and 10.2% of TCs over the western North Pacific and those making landfall in China, respectively. TCs crossing Jiangsu Province make landfall in China mainly in June–November from genesis through entering Jiangsu, with highest landfalling frequency and widest landfalling distribution in August. The landfalling routes of TCs crossing Jiangsu are categorized into 14 types (T1~T14), of which route T4 that make landfall first in Taiwan and then in Fujian account for the highest proportion. The tracks of TCs crossing Jiangsu are classified into four types. The moving directions within Jiangsu and overall track morphologies of TCs in these four types are closely related to the westward extension and northward shift of the western North Pacific subtropical high. TCs enter and leave mainly from the southeast and east coast of Jiangsu, respectively, in July–September. The entering locations of TCs crossing Jiangsu shift northward from June to August and retreat southward in September–October, while leaving locations shift westward and then retreat eastward, due to seasonal adjustments of large-scale systems, such as the western North Pacific subtropical high and monsoon circulation. The track density of TCs in Jiangsu generally decrease from southeast to northwest, with most of the TCs moving northward or northeastward. The spatial distributions of track density and average velocity vectors of TCs crossing Jiangsu are characterized by significant monthly variations. There is a significant increase in potential destructiveness of TCs in Jiangsu (JS-PDI) during the period of 1949-2021, corresponding to increases in their landfall intensity and average intensity in Jiangsu. The JS-PDI in August is considerably higher than in other months. In agreement with the distribution of average TC intensity in Jiangsu, larger JS-PDI values are mainly distributed in the coastal region and southeast of Jiangsu, and the locations of maximum JS-PDI and track density are well matched.

     

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