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气象:2023,49(12):1435-1450
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“23·7”华北特大暴雨过程雨强精细化特征及动力和热力条件初探
符娇兰,权婉晴,麦子,罗琪,陈涛,李晓兰,许先煌,朱文剑,华珊,韩旭卿
(国家气象中心,北京 100081)
Preliminary Study on the Refined Characteristics of Rainfall Intensity and Dynamic and Thermodynamic Conditions in the July 2023 Severe Torrential Rain in North China
FU Jiaolan,QUAN Wanqing,MAI Zi,LUO Qi,CHEN Tao,LI Xiaolan,XU Xianhuang,ZHU Wenjian,HUA Shan,HAN Xuqing
(National Meteorological Centre, Beijing 100081)
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投稿时间:2023-10-17    修订日期:2023-11-26
中文摘要: 基于ERA5再分析资料、国家级和区域级地面气象观测、双偏振多普勒雷达、地面雨滴谱仪、闪电定位仪、风廓线雷达等多源观测资料,对“23·7”华北创纪录极端降水过程中雨强的精细化特征,导致极端降水的中尺度对流系统(MCS),极端降水的微物理特征及动力和热力条件进行了分析。结果表明:整个过程小时雨强表现出面弱点强的特点,局地小时、分钟级雨强具有极端性。雨强阶段性特征明显,2023年7月30日08:00至31日20:00(第二阶段)雨强最强,与多个β-MCS发展有关,并伴有后向传播及列车效应等中尺度过程,降水以中等直径、高浓度雨滴为主,具有一定量的低浓度大粒子雨滴样本,属于海洋性与大陆性混合型降水,暖云碰并与冰晶聚合融化过程共存。7月29日08:00至30日08:00(第一阶段)和7月31日20:00至8月2日08:00(第三阶段)雨强相对较小,对应于前者的MCS垂直伸展高度较低、强度不强,以暖云降水为主导,雨滴浓度高、直径中等,对应于后者的MCS发展强盛,但移动速度快,也具有海洋性与大陆性降水混合型降水特征。三个阶段的大气整层可降水量最大值均超过70mm,第一阶段天气尺度强迫强,对流有效位能(CAPE)在500J·kg-1左右,MCS发展高度相对较低;第二阶段后期天气尺度强迫有所减弱,但华北中南部对流不稳定能量再次重建,上游地区CAPE较第一阶段有所增大(600~1000J·kg-1),导致极端降水的 MCS发展为深厚湿对流系统,雨强明显增大;第三阶段天气尺度强迫明显减弱,低层偏南风脉动辐合和大的CAPE为MCS强烈发展提供了有利条件。
Abstract:Based on the ERA5 reanalysis data and the multi-source observations such as ground national and regional automatic weather stations, dual polarization radar, ground raindrop spectrometer, lightning locator, wind-profiling radar, we analyze the refined characteristics of rainfall intensity, the mesoscale convective system (MCS) responsible for the extreme precipitation, the microphysical features as well as dynamic and thermodynamic conditions of the July 2023 extremely severe precipitation process in North China. The results indicate that the hourly rainfall intensity in this event was characterized by weak in most areas but strong at some stations, and the local hourly and minute-level rainfall intensities both reached the extremity level. The stage feature of the rainfall intensity was obvious, with the rainfall intensity being strongest in the second stage from 08:00 BT 30 to 20:00 BT 31 July. This was caused by several β-MCSs and accompanied by mesoscale processes such as backward propagation and train effect. The severe precipitation was mainly composed of high concentration raindrops with medium diameters, and had a certain amount of low-concentration large particle raindrop samples. Thus, this extreme rainfall event belonged to a mixed type with precipitation of oceanic and continental nature, in which warm clouds collided, coexisting with ice crystal aggregation and melting. In the first stage (from 08:00 BT 29 to 08:00 BT 30 July) and the third stage (from 20:00 BT 31 July to 08:00 BT 2 August) the rainfall intensity was relatively small. The former had a low vertical extension height and weak intensity of MCS, dominated by warm-cloud precipitation, and the raindrops had high concentrations and medium diameters. The MCS responding to the latter developed vigorously, but it moved fast. So, it also had the characteristics of mixed-type oceanic and continental precipitation. The maximum values of integrated precipitable water in the three stages all exceeded 70 mm. In the first stage, the synoptic scale forcing was strong, and the convective available potential energy (CAPE) was around 500 J·kg-1. The vertical height of MCS was relatively low. In the second half period of the second stage, the synoptic scale forcing was weakened, but the unstable convective energy in the central and southern parts of North China was rebuilt again. The CAPE in the upstream region became increased compared to the value in the first stage (600-1000 J·kg-1), causing the extreme-rainfall-related MCS to have developed into a deep wet convective system and the rainfall intensity increased significantly. In the third stage, the synoptic scale forcing was greatly weakened. The convergence of southerly wind pulsations at low level and the large CAPE provided favorable conditions for the vigorous development of MCS.
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基金项目:国家重点研发计划(2022YFC3003905)、国家自然科学基金项目(U2142214)、中国气象局气象能力提升联合研究专项(23NLTSZ007)和中国气象局暴雨精细化分析和预报青年创新团队专项共同资助
引用文本:
符娇兰,权婉晴,麦子,罗琪,陈涛,李晓兰,许先煌,朱文剑,华珊,韩旭卿,2023.“23·7”华北特大暴雨过程雨强精细化特征及动力和热力条件初探[J].气象,49(12):1435-1450.
FU Jiaolan,QUAN Wanqing,MAI Zi,LUO Qi,CHEN Tao,LI Xiaolan,XU Xianhuang,ZHU Wenjian,HUA Shan,HAN Xuqing,2023.Preliminary Study on the Refined Characteristics of Rainfall Intensity and Dynamic and Thermodynamic Conditions in the July 2023 Severe Torrential Rain in North China[J].Meteor Mon,49(12):1435-1450.