2016年江淮地区梅汛期首场持续性暴雨的持续原因初探

利用NCEP/NCAR的再分析资料和逐6 h降水实况观测资料，对2016年6月30日—7月6日江淮地区首场持续性暴雨的持续原因进行了初步分析。结果表明，此次持续性暴雨的主雨带位于西太平洋副热带高压(简称西太副高，下同)的西北侧、中低层江淮切变线的南侧，高空急流入口区的右侧，低空急流轴的左前侧；高空强辐散与低空强辐合长时间维持为暴雨的持续提供了有利的动力条件，西风槽前和西太副高外围两个水汽通道为此次暴雨过程提供了充分的水汽，其周期性辐合为暴雨的持续提供了有利的水汽条件；江淮流域上空大气上干冷、下暖湿状态的重复形成，为暴雨的持续提供了足够的能量；江淮切变线附近中尺度低涡的新生、发展和维持为暴雨的持续提供了持续的辐合抬升条件；锋生的周期性增强对降水强度的预报具有一定指示意义。 

PRELIMINARY ANALYSIS ON THE CAUSES OF THE FIRST PERSISTENT HEAVY RAINFALL IN YANGTZE-HUAIHE RIVER VALLEY IN 2016

Based on NCEP/NCAR 1 °×1 ° reanalysis data and 6-hourly precipitation observation data, this paper analyzes the causes of the first persistent rainstorm in Jianghuai area from June 30 to July 6, 2016. The results show that the precipitation was composed of four heavy rain processes, and the main rain band was located on the northwest side of the western Pacific Subtropical High (WPSH), the south side of a middle- and low-level Changjiang-Huaihe shear line, the south of an upper-level jet stream area, and the north side of a low-level jet. Favorable dynamic conditions were provided by strong divergence in the upper level and strong convergence in the low level. Two water vapor channels in front of the westerly trough and WPSH provided sufficient water vapor for the rainstorm. Favorable moisture conditions were provided by the cycle of moisture convergence. Unstable atmospheric environment formed because it was dry and cold in the upper level and warm and humid in the Huaihe River basin. Sustained convergence and uplifting conditions were provided by the generation, development and maintenance of mesoscale vortexes near the Yangtze Huaihe shear line. Low-level frontogenesis is significant for precipitation forecast.