Abstract: Based on the conventional meteorological observation data, regional automatic weather station observation data, and NCEP reanalysis data, the environmental field characteristics and triggering mechanism of a rainstorm in Shandong from 15 to 16 May 2018 were analyzed. The results are as follows: (1) This rainstorm process was consisted of both warm sector rainstorm and frontal rainstorm. The main influencing systems of warm sector rainstorm included the high trough, the warm shear line and the ground convergence line. (2) Before the beginning of the warm sector rainstorm, the atmosphere had unstable environmental conditions of convection. (3) The warm sector rainstorm near the warm shear on 850 hPa had obvious energy front, while the energy front of the rainstorm in the local geothermal area in the southward airflow on the south side of the warm shear was not obvious. (4) During the warm sector rainstorm, the vertical wind shear over the rainstorm area reached the shear magnitude of medium or higher intensity. Vertical environmental conditions were favorable for the occurrence and development of convective weather in warm sector. (5) The mesoscale convergence line on the ground was the trigger mechanism of rainstorm in warm area. The position and moving direction of convergence line were consistent with the falling area and moving direction of the rainbelt. (6) The enhancement and down propagation of low-level jet stream and ultra-low-level jet stream would also trigger the release of unstable energy.

Key words: environmental field, triggering mechanism, warm sector rainstorm, jet streams

摘要： 利用常规观测资料、区域自动站及NCEP再分析资料，对2018年5月15—16日山东暴雨过程的环境场特征和触发机制进行分析。结果表明：（1）该暴雨过程分为暖区暴雨和锋面暴雨2个时段，高空槽、暖切变线和地面辐合线是造成暖区暴雨的主要影响系统；（2）暖区暴雨开始前大气具有产生对流的不稳定环境条件；（3）850 hPa暖切变附近的暖区暴雨有明显的能量锋区，而发生在暖切变南侧暖区的暴雨锋区不明显；（4）暖区暴雨期间，暴雨区上空的垂直风切变均达到中等以上强度，垂直环境条件有利于暖区对流天气的发生、发展；（5）地面中尺度辐合线是暖区暴雨的触发机制，辐合线的位置和移动方向与雨带的落区和移动方向一致；（6）低空急流和超低空急流的加强和向下传播也会触发不稳定能量的释放。

关键词: 环境场, 触发机制, 暖区暴雨, 急流