“7.29”华北地区强降水过程基本特征分析

Analysis “7.29” Extreme Heavy Rainfall Process in North China

本文利用常规地面和高空气象观测、机场报文、FY-2G卫星红外亮温(TBB)、NCEP再分析等资料,对2023年7月29日至8月1日双台风天气背景下,发生在华北地区的一次极端强降水过程的总体降水特征和主要机场降水情况进行了总结,通过大尺度环流特征、水汽输送和局地动力抬升条件等要素分析,进一步揭示了强降水过程的成因。结果表明:本次过程的北京首都和大兴机场持续时长超过10小时,降水量约为北京市年平均降水量的一半;副热带高压与大陆高压脊合并后稳定维持,使“杜苏芮”的残留低涡北上停滞,为强降水的发生提供了稳定的环流背景;双台风“杜苏芮”和“卡努”为强降水的发生提供了充沛的水汽和能量,是长时间维持降水的关键因素;太行山地形的强迫抬升,增大了水汽的垂直输送,使降水增幅。本文为提高极端降水预报水平,保障航班运行安全提供了基础科学支撑。

In this paper, the overall precipitation characteristics and precipitation conditions of major airports of an extreme heavy precipitation process that occurred in North China during July 29 to August 1, 2023 affected by twin-typhoon system are summarized. The cause of the heavy precipitation process are further clarified by analyzing the characteristics of large-scale circulation, water vapor transport and local dynamic lifting conditions, based on surface and upper air meteorological observations, reports of routine and special observations, FY-2G satellite TBB data and NCEP reanalysis data. The results show that, the accumulated precipitation of this process at both Beijing Capital International Airport and Daxing International Airport lasted for more than 10 hours and reached half of the average annual precipitation of Beijing;a stable circulation background sustained since the merging of the subtropical high and the continental high kept the residual low vortex of Typhoon Doksuri from moving northward;the abundant water vapor and energy provided by the twin typhoon system Doksuri and Khanun is crucial to maintain the precipitation;the forced uplift of Taihang Mountain terrain increased the vertical transport of water vapor and the intensity of the precipitation. This paper provides basic scientific support for improving the level of extreme precipitation prediction and ensuring the safety of flight operation.