【摘要】 利用常规观测、地面加密资料和欧洲细网格等产品，对2021年7月21—23日豫北极端暴雨天气过程的天气学成因进行了分析。结果表明：副热带高压、大陆高压、低涡和台风等多种天气系统为极端暴雨提供了稳定的环流背景。高层强辐散、中低层辐合形成强烈的垂直上升运动，加之深厚的湿层，使水汽、热量垂直输送加剧，对天气系统的发展有促进作用。持续加强的偏东风和超低空急流给豫北地区带来充沛的水汽和暖湿不稳定能量；绝对湿度厚度的增加、极大的整层可降水量在豫北形成极高的降水效率；地面中尺度气旋、辐合中心和边界层辐合线的形成、维持与阶段性强降水有很好的对应关系；风场辐合区出现的时刻提前于强降水出现时刻，可根据地面加密风场辐合中心、辐合线位置及其移动方向推断强降水落区。太行山脉对气流的阻挡及强迫抬升作用引起中低层的闭合环流，为强降水系统长时间维持提供有利条件，并对降水有明显的增幅作用，强降水区域出现在太行山东麓30到50 km范围。更多还原

【Abstract】 In this paper, conventional observations, ground densely-observed data and European fine grid products are used to analyze the synoptic causes of the extreme rainstorm process that happened in northern Henan from July 17 to 23, 2021. The results show that many factors such as subtropical high, continental high, low vortex and typhoon provided a stable circulation background for the extreme rainstorm. Strong divergence at high level and convergence at the middle and lower levels led to strong vertical upward movement, and the deep wet layer intensified the vertical transport of water vapor, heat and momentum, which had a positive feedback effect on the development of the severe weather system. The continuously-strengthened easterly and ultra-low-level jet brought abundant water vapor and warm-humid unstable energy to northern Henan. The increase of absolute humidity thickness and extremely high whole-layer precipitable water formed very high precipitation efficiency over northern Henan. The formation and maintenance of ground meso-scale cyclone, convergence center and boundary layer convergence line corresponded well to periodic severe precipitation. The occurrence time of wind field convergence zone was earlier than that of extreme rainfall, The heavy rainfall area can be inferred from the convergence center, convergence line position and moving direction of the ground densified wind field. The mechanical barrier and forced uplift of the Taihang Mountains to the air flow resulted in the middle and low-level secondary circulation, which provided strong conditions for the long-term maintenance of the severe precipitation system, and had an obvious increasing effect on the generation of precipitation. The heavy precipitation area was 30—50 km away from the east piedmont of the Taihang Mountains.更多还原