青海东部一次副高控制下强对流天气分析

Analysis of a Severe Convective Weather Event under the Control of the Western Pacific Subtropical High in Eastern Qinghai

摘要: 2022年8月9日傍晚至10日凌晨青海省东部出现了一次强降水天气。此次强降水天气出现在副高控制的背景下，各家数值预报模式对此次的强降水过程预报效果较差。本文利用多种常规和非常规观测资料，对此次青海副高内部的极端降水过程中进行分析，希望发现一些预报指标，以提升预报准确率。结果表明：(1) 此例暴雨属于500 hPa无明显影响系统，底层无急流背景下的副高控制型暴雨。在青海东部“喇叭口”“迎风坡”地形影响下，配合偏东风暖湿气流加强和局地地形、冷池出流边界共同作用而诱发产生的强降水，降水时间短，降水强度大，局地性强。(2) 降水开始到强盛的期间，始终有边界层地形作用产生的水平辐合、抬升运动加剧了降水强度。(3) 短时强降水的大值中心与地形分布有高度的一致性，出现在河谷绝对湿度大并且有暖中心配合的地区。

Abstract: From the evening of August 9 to the early morning of August 10, 2022, a severe precipitation event occurred in eastern Qinghai Province. This heavy rainfall developed under the background of the western Pacific subtropical high (WPSH) control. Numerical weather prediction models from various centers performed poorly in forecasting this event. Utilizing multiple conventional and unconventional observation datasets, this study analyzes the mechanisms of this extreme precipitation event within the WPSH over Qinghai, aiming to identify potential forecasting indicators to improve prediction accuracy. The results indicate that: (1) This torrential rain event occurred without a pronounced 500-hPa synoptic system or low-level jet stream, characteristic of WPSH-controlled heavy rainfall. It was triggered by the combined effects of enhanced easterly warm-moist airflow, localized topography (specifically the “horn-shaped” valley and windward slope effects in eastern Qinghai), and the outflow boundary of a cold pool. The event featured short duration, high intensity, and strong locality. (2) From the onset to the peak of precipitation, persistent boundary-layer convergence and forced lifting induced by terrain significantly enhanced the rainfall intensity. (3) The maxima of short-term heavy precipitation were highly consistent with the terrain distribution, occurring in valleys characterized by high absolute humidity and collocated with warm cores.