中国近海热带气旋快速增强的两种判别指标对比

Comparison of Two Diagnostic Criteria for Rapidly Intensifying Tropical Cyclones over China's Offshore Waters

关键词:  热带气旋  快速增强  近海  统计

Key words:  tropical cyclone  rapid intensification  offshore waters  comparative analysis

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。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。(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 20 世纪 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。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:

The sudden and destructive nature of rapidly intensifying tropical cyclones (TCs) over offshore areas has garnered considerable attention in research and operational forecasting. The mainstream criteria for identifying rapid intensification (RI) of TCs fall into two categories: changes in minimum central pressure and maximum wind speed. Utilizing the TC best-track dataset compiled by the Shanghai Typhoon Institute of China Meteorological Administration, the present study employed 12-h changes in minimum central pressure and maximum wind speed as diagnostic criteria to identify rapidly intensifying tropical cyclones (RITCs) offshore China from 1980 to 2019. The findings are as follows: (1) While both criteria yielded comparable RITC counts, case concordance rates were generally low, peaking in the 2010s (highest overlap) and reaching minima in the 2000s. (2) The criterion based on the 12-h maximum wind speed change exhibited higher sensitivity to variations in the time span of the data, with greater fluctuations in the corresponding RI thresholds. (3) The largest discrepancies in the RI samples identified by the two criteria were observed annually in the 1980s, monthly in September, and diurnally at 0600 Universal Time Coordinated. (4) Spatially, the 12-h maximum wind speed change criterion was more sensitive offshore northern Taiwan, southern East China Sea, and western Guangxi, whereas the 12-h minimum central pressure change criterion was more sensitive in eastern Guangxi waters. These findings provide operational guidance for RITC monitoring in China's offshore areas.