台风“温比亚”造成河南特大暴雨诊断分析
Diagnosis and Analysis of the Extraordinary Rainstorm Caused by Typhoon “Rumbia” in Henan Province
中文摘要：
2018年8月17—19日受第18号台风“温比亚”影响，河南省东部地区出现了历史罕见的极端暴雨天气，由于台风低压18日凌晨进入河南以后移速明显减慢，在河南境内滞留长达40 h，给河南带来了强的风雨天气，其中有8个国家气象站日降水量突破建站以来历史极值。为了全面认识台风低压长时间滞留及豫东极端暴雨发生发展机制，利用常规探空和地面观测数据以及NCEP 1°×1°再分析资料，从环流背景、大气稳定度、动力、热力、水汽等方面对2018年8月17—19日台风暴雨过程进行了全面细致的诊断分析，结果表明：强降水中心位于距低压约50 km处的螺旋云带内，强烈发展的斜升气流是产生强降水的根本原因；过程发生前大气已具备强对流发生发展的能量及不稳定条件，倾斜发机制长时间维持并伴有充足的水汽供应及强烈辐合上升运动，且不断有对流单体生成、合并发展为较强雷暴单体，以及强回波长时间稳定少动等是产生强降水的直接原因。高层引导气流变弱、中低层高压带阻挡，使得台风低压在河南境内长久徘徊。将商丘站的相关环境参数标准差倍数与历年出现暴雨时的平均值和最大值进行对比发现，本次过程各环境参数标准差倍数明显高于历年平均值，且部分达到历史最大值，具有一定极端性。
中文关键词：
台风，降水，大尺度环流，不稳定层结，水汽
KeyWords：
typhoon, precipitation, large-scale circulation,unstable stratification, water vapor
Abstract：
Under the influence of No. 18 Typhoon “Rumbia”, a rarely-seen extreme rainstorm occurred in the eastern area of Henan Province during 17－19 August 2018. The movement speed of the typhoon low pressure slowed down significantly after entering Henan in the early morning of the 18th and stayed there for 40 hours, which resulted in strong wind and heavy rain in Henan. The daily precipitation of 8 national meteorological stations exceeded the historical extreme value since the establishment of the station. In order to fully understand the long-term retention of typhoon low pressure and the occurrence and development mechanism of extreme rainstorms in eastern Henan, the paper conducts a comprehensive and detailed diagnostic analysis of the typhoon and the rainstorm process during 17－19 August 2018 from the circulation background, atmospheric stability, dynamics, thermodynamics and water vapor by using conventional sounding and ground observation data and NCEP 1°×1° reanalysis data. The results show that the center of the heavy precipitation is located in the spiral cloud belt about 250 km away from the low pressure and the strongly developed ramp-up airflow is the fundamental cause of the heavy precipitation. Prior to the extreme rainfall process, the atmosphere already has the energy and instability for the occurrence and development of strong convection. The inclined development mechanism has been maintained for a long time, accompanied by sufficient water vapor supply and strong convergence and upward movement, the continuous generation of convective cells, the merger and development of strong thunderstorm cells, and the stable and infrequent movement of strong echo wavelengths. These are the direct reasons for the occurrence of the heavy precipitation. The weakening of the high-level guided airflow and the blocking of the middle and low-level high pressure belts make the typhoon low pressure linger in Henan Province for a long time. Comparing the standard deviation multiples of relevant environmental parameters with the average and maximum values over the years when heavy rainfall events occurred at Shangqiu Station, it is found that the standard deviation multiples of each environmental parameter in this process of extreme rainfall are significantly higher than the average value over the years and some of them have reached the historical maximum value, exhibiting certain level of extremity.