Comparison of two criteria of rapidly intensifying tropical cyclones over the offshore of China
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摘要: 近海快速增强的热带气旋(TC)具有猝不及防的破坏性,其研究和业务预报一直备受关注。判别TC快速增强(RI)的主流指标有两类,即TC中心最低气压变化值和最大风速变化值。本文利用中国气象局整编的热带气旋最佳路径数据集资料,分别以12 h中心最低气压变化值和最大风速变化值作为判别指标,对1980—2019年中国近海快速增强的热带气旋(RITC)进行判别,并对得到的结果进行对比分析。结果表明:(1)两种判别指标得到的RITC的数量差异较小,但RITC个例的重合率并不高,其中,RITC个例的重合率在本世纪00年代差异最大,10年代差异最小。(2)12 h最大风速判别指标对统计资料时间跨度的变化表现出更高的敏感度,所对应的RI阈值的波动更大。(3)两种判别指标得到的RI样本的最大差异值在年际上出现在80年代,月际上出现在9月,日变化上出现在06时(Universal Time Coordinated,UTC)。(4)在区域分布上,以12 h最大风速变化为判别指标在台湾北部、东海南部以及广西西部近海区域具有较高的敏感度,而以12 h最低气压变化为判别指标则在广西东部近海区域的敏感度更高。本文的研究结论对遴选(判别)我国近海RITC样本(个例)具有一定的参考意义。Abstract: Rapid intensification (RI) of offshore tropical cyclones (TCs) poses unexpected destructive threats, attracting significant research and operational interest. The mainstream criteria for identifying RI of TCs fall into two categories: the change in the minimum central pressure of the TC and the change in the maximum wind speed. This study utilizes the TC best-track dataset compiled by the Shanghai Typhoon Institute of China Meteorological Administration (STI/CMA), using the 12h changes in minimum central pressure and maximum wind speed as discriminant criteria to identify RITCs over the offshore areas of China from 1980 to 2019. The results of this identification are then compared and analyzed. Results indicate that (1) The number of RITCs identified by the two criteria shows little difference, but the overlap rate of individual RITCs is not high. The difference is greatest in the 2000s and smallest in the 2010s. (2) The criterion based on the 12h maximum wind speed change exhibits higher sensitivity to variations in the time span of the statistical data, with greater fluctuations in the corresponding RI thresholds. (3) The largest discrepancies in the RI samples identified by the two criteria appear annually in the 1980s, monthly in September, and diurnally at 06 UTC(Universal Time Coordinated,UTC). (4) Regionally, the 12h maximum wind speed change criterion is more sensitive in the offshore areas north of Taiwan, south of the East China Sea, and west of Guangxi, whereas the 12h minimum central pressure change criterion is more sensitive in the offshore areas east of Guangxi. Our conclusions could provide valuable insights for identifying samples and cases of RITCs in China's offshore areas.
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Key words:
- tropical cyclone /
- rapid intensification /
- offshore /
- statistics
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