陕北黄土高原一次区域性暴雨诊断分析

Diagnostic Analysis of a Regional Rainstorm on the Loess Plateau in Northern Shaanxi

利用NCEP 1°×1°再分析资料和黄土高原东部288个自动站资料,分析了2018年7月10日区域性大暴雨过程。结果表明:冷涡底部下滑槽与副高外围暖湿气流的相互作用是形成这次暴雨的主要成因。远距离台风使低空急流加强,高低空急流耦合为暴雨的发生提供了强烈的动力条件。θ_(se)能量舌向河套地区的伸展与午后增温加剧了能量的增长,二者共同为暴雨区提供了热力条件。台风西进,副高北抬,使系统缓慢东移,影响系统长时间维持在陕西北部上空,是造成强降水持续的重要因素。

NCEP 1 ° × 1 ° reanalysis data and 288 automatic stations data in the east of the Loess Plateau were used to analyze the regional heavy rainstorm process on July 10,2018.The results show that the interaction between the bottom glide trough of the cold vortex and the warm and humid air flow around the subtropical high is the main cause of this rainstorm.Long distance typhoons strengthen the low-level jet stream,and the coupling of high-level and low-level jet streams provides a strong dynamic condition for the occurrence of rainstorm.The extension of θ_(se) energy tongue towards the Hetao area and the afternoon warming aggravated the energy growth,which together provided the thermal conditions for the rainstorm area.The typhoon moves westward and the subtropical high lifts northward,causing the system to slowly move eastward and affecting the long-term maintenance of the system over northern Shaanxi,which was an important factor causing sustained heavy precipitation.