“黑格比”台风浙沪交界极端降水及物理量特征分析

ANALYSIS OF EXTREME PRECIPITATION IN THE ADJOINING AREA OF ZHEJIANG AND SHANGHAI AND PHYSICAL QUANTITY CHARACTERISTICS OF TYPHOON HAGUPIT

关键词:  “黑格比”  台风  极端降水  极值排序

Key words:  Hagupit  typhoon  extreme rainstorm  extreme value ranking

摘要:

利用全国综合气象信息共享平台(CIMISS)地面站点降水资料、欧洲中期天气预报中心逐小时再分析资料，分析 “黑格比”台风登陆后在浙江嘉兴、上海金山交界地区(简称“关注区”)产生的极端降水及相关物理量特征，结果表明：(1) 此次降水过程的小时雨强、日降水和过程降水均具有很强的极端性，部分测站达十年一遇甚至是百年一遇标准，杭州湾北岸强降水的极端性比南岸更显著；(2) 关注区对流层低层充足的水汽，以及高低层冷、暖平流的叠加，为极端降水发生发展提供了有利的水汽条件和不稳定条件；(3) 根据物理量的逐小时演变，呈现出低层辐散、高层辐合的环流增强，以及低层强烈的涡旋运动，关注区强降水也随之发生；(4) 此次极端暴雨过程850 hPa第二类热成风螺旋度极值和地面散度经极值排序后呈现较高的百分位置，在相似台风中均具有显著的极端性，对类似路径、小体积台风极端降水的发生具有较好的指示意义。

Abstract:

Using the precipitation data from ground stations of the China Integrated Meteorological Information Sharing System (CIMISS) and the hourly reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF), we analyzed the characteristics of extreme precipitation and related physical quantities in the junction area of Jiaxing, Zhejiang Province and Jinshan, Shanghai City (referred to as the "focus area") after the landfall of Typhoon Hagupit. The results showed that: (1) the daily rainfall amount, hourly rainfall amount and total rainfall amount of this rainstorm were extreme, and the precipitation recorded by some stations was rarely observed in more than 10 years, or even in more than 100 years, and the precipitation on the north bank of Hangzhou Bay was more extreme than that on the south bank; (2) In the focus area, sufficient water vapor in the lower troposphere with the superposition of upper-level cold advection and lower-level warm advection provided favorable water vapor condition and unstable condition for the occurrence and development of extreme precipitation; (3) According to the hourly evolution of physical quantities, there was an enhanced circulation of low-level dispersion and high-level convergence, as well as strong vortex motion at low levels, leading to the occurrence of extreme precipitation in the focus area; (4) During this extreme rainstorm, the 850 hPa second-type thermal helicity and divergence showed a high percentage position after the extreme values ranked. It suggests that these two physical quantities have significant extremes among similar typhoons, which can help indicate the occurrence of extreme precipitation of small-volume typhoons with similar paths.