汛期博州东部最早一次强降水天气成因分析

Analysis on Weather Causes of the Earliest Heavy Precipitation in the East of Bozhou in Flood Season

摘要: 本文主要利用Micaps高空、地面天气实况、模式预报0时刻资料及新疆博州区域自动站资料，运用天气动力学诊断方法，综合分析2022年5月5~6日博州东部强降水天气过程。此次暴雨大值落区位于博州南北部沿山及精河，500 hPa乌拉尔大槽不断分裂短波与中亚低槽结合影响北疆，低层博州受暖低压影响，高层冷低层暖，冷暖交绥，中高层偏南风与低层偏北风形成垂直环流，配合700 hPa伊犁博州之间冷式切变、中尺度气旋及地形抬升触发下，造成中尺度对流，形成短时强降水。中层气团自阿拉伯海移至伊犁州境外，水汽辐合上升经别珍套山、科古琴山进入博州南部。CMA模式对强降水落区预报好于定点预报，组合反射率及k指数对对流性降水预报有一定的指示意义；ECMWF模式预报落区较好但单点预报量级偏大，模式时间垂直剖面能一定程度地反映降水时段。通过CMA及ECMWF模式预报性能检验，为以后博州东部定时、定点暴雨预报预警提供依据。

Abstract: Based on Micaps facts, model prediction data at 0 time and automatic station data, the weather process of heavy precipitation in the east of Bozhou during May 5~6, 2022 was comprehensively analyzed by using the diagnostic method of weather dynamics in this study. The heavy rainfall area was located along the mountains and Jinghe River in the south and north of Bozhou. The 500 hPa Ural Trough continuously split short wave and combined with the Central Asian low trough to affect northern Xinjiang. The low level Bozhou was affected by the warm low, and the upper level cold and lower level warm, and the cold and warm interacted, and the southerly wind in the middle and upper level formed vertical circulation with the north wind in the lower level. Combined with 700 hPa cold shear between Bozhou and Yili, mesoscale cyclone and topographic uplift triggered mesoscale convection and short-time heavy precipitation, the middle air mass moved from the Arabian Sea to the outside of Yili prefecture, and the water vapor converged and rose through Beizhen Tao and Keguqin Mountains to enter the south of Bozhou. The CMA model is better than the fixed point forecast for the heavy precipitation falling area, and the combined reflectance and k index have certain indicative significance for the convective precipitation forecast. The ECMWF model has a good forecast area, but the magnitude of single point forecast is larger. The vertical profile of model time can reflect the precipitation period to a certain extent. The forecast performance test of CMA and ECMWF model provides the basis for the forecast and early warning of regular and fixed heavy rain in the east of Bozhou.