2018年山东一次极端暴雨的环境场特征分析

Environmental Characteristics of Historical Extreme Rainstorm in Shandong Province Caused by Typhoon Rumbia

利用多源气象数据资料,对2018年8月17—20日台风“温比亚”引发山东历史极端暴雨的环境场进行研究。结果表明:(1)台风“温比亚”影响山东,引起的前期强降水位于鲁南地区,主要为台风外围螺旋云系降水,19日白天至夜间是此次强降水主要时段,主要受台风和西风槽相互作用引起,落区主要集中于台风倒槽附近。(2)副高稳定少动、中低纬系统相互作用及低空急流的稳定维持是此次台风强降水的主要原因。(3)超低空急流相比低空急流对出现强降水更具指示意义,强度大小影响降水的强弱程度,且超低空(500 m以下)出现20 m·s^(-1)以上的强风速对短时强降水有明显指示作用。低空急流指数对强降水特别是中小尺度强降水及雨强大小有一定预示作用。(4)特殊地形在此次台风暴雨中有较大作用,地形的迎风坡效应在山地产生的强迫抬升作用及山脉阻挡引起的水汽在山前积聚等动力和热力共同作用触发湿对流是此次台风出现短时强降水的重要触发机制。(5)此次台风暴雨过程Q矢量散度负值的强弱对于未来6 h雨强大小有较好的指示意义。另外,此次台风特大暴雨与冷空气密切相关。

Based on the multi-source meteorological data,the environmental characteristics of historical extreme rainstorm in Shandong province caused by Typhoon Rumbia in 2018 were analyzed.The results showed that:(1)The early heavy precipitation caused by Typhoon Rumbia is located at southern Shandong province,mainly due to the spiral cloud system in the periphery of typhoon,the main period of the heavy precipitation is from day to night on the 19th August,mainly caused by the interaction between typhoons and westerly troughs.The heavy precipitation area is mainly concentrated near the typhoon’s inverted trough.(2)The main reasons for the heavy precipitation are the stable and infrequent movement of the subtropical high,the interaction of the middle and low latitude weather systems and the stable maintenance of the low-level jet.(3)Compared with the low-level jet,the ultralow-level jet has a more obvious indicator for the heavy rainfall,and its intensity affects the intensity of the precipitation,and the strong wind speed of more than 20 m·s^(-1) below the altitude of 500 meters has an obvious indicator on the short-term heavy precipitation.The low-level jet index has a certain predictive effect on the appearance of heavy precipitation,especially on the small and medium scale heavy precipitation and the intensity of rainfall.(4)The special topography played a key role in this typhoon rainstorm.The wet convection is triggered by the combined action of dynamics and heat,such as the forced uplift of the mountain by the windward slope effect of the terrain and the accumulation of water vapor in the front of the mountain caused by the blocking of the mountain is an important triggering mechanism for the short-term heavy precipitation.(5)The intensity of negative Q-vector divergence can affect the rainfall intensity in the next 6 hours.In addition,the heavy rain is closely related to the cold air.