2018年8月2日~4日海东暴雨天气过程分析

Analysis of Rainstorm Weather Process in Haidong on August 2-4 in 2018

摘要: 2018年8月2日~4日，受西亚大槽分裂的短波槽影响，青海东部出现了一次大降水天气过程，此次降水过程持续时间较长，降水强度以及总降水量都属历史同期罕见。利用MICAPS实时观测资料和NCEP再分析资料(2.5˚ × 2.5˚)对本次降水过程的降水实况，天气环流形势，水汽条件，动力条件，不稳定条件和卫星云图等几方面进行分析。结果表明：本次降水过程主要受青海北部西亚大槽分裂的短波槽以及青海出现的低涡及切变线等天气系统的影响，是典型的北槽南涡型大降水天气；暴雨过程的水汽输送主要分为两路，一路是从孟加拉湾和南海途经四川盆地到青海东部，另一路是从东海向东直接输送到青海。输送来的大量水汽在低层辐合并向上输送，形成深厚的湿层，为暴雨的发生提供水汽条件。低空辐合，高空辐散以及从低空到高空的垂直上升运动为暴雨的发生发展提供了动力条件；低层中西亚大槽断裂的短波槽携带的槽后干冷空气和西太平洋副热带高压西南侧输送的偏南暖湿气流交汇，大气处于不稳定的状态；β中尺度对流云团在700 hPa切变线附近发展，表明此次降水过程有中小尺度系统的参与。

Abstract: On August 2-4, 2018, under the influence of the short-wave trough split in West Asia, a heavy precipitation weather process occurred in eastern Qinghai. The precipitation process lasted for a long time, and the precipitation intensity and total precipitation is rare in the same period of history. In the paper, the real-time observation data of MICAPS and NCEP data (2.5˚ × 2.5˚) are used to analyze the precipitation, weather situation, water vapor conditions, dynamic conditions, unstable conditions and satellite cloud images of this precipitation process. The results show that the precipitation process is mainly affected by the short wave trough split in the West Asia trough in the north of Qinghai and the low vortex and shear moving northward in Qinghai, which is a typical heavy precipitation weather in the north-trough with south-vortex. The water vapor transport in the rainstorm process is mainly divided into two ways; one is from the Bay of Bengal and the South China Sea through Sichuan Basin to the east of Qinghai, and the other is directly from the East China Sea to Qinghai. A large amount of water vapor converges in the lower layer and is transported upward to form a deep wet layer, which provides water vapor conditions for the occurrence of torrential rain. A large amount of water vapor converges in the lower layer and is transported upward to form a deep wet layer, which provides water vapor conditions for the occurrence of torrential rain. Low-level convergence, high-altitude divergence and vertical ascending motion from low to high provide dynamic conditions for the occurrence and development of torrential rain. In the lower layer, the dry and cold air behind the trough from the short wave trough of the West Asia trough converges with the southerly warm and humid air transported to the southwest of the West Pacific subtropical high, and the atmosphere is in an unstable state. The development of β mesoscale convective cloud clusters near the 700 hPa shear line indicates that meso- and small-scale systems are involved in this precipitation process.