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投稿时间：2022-03-24 修订日期：2022-07-27
投稿时间：2022-03-24 修订日期：2022-07-27
中文摘要: 针对河南“21·7”特大暴雨的极端降水天气过程，利用FNL大气再分析资料、国家基准站降水观测数据和高分辨率的数值模拟结果，开展了暴雨多尺度系统协同作用下水汽输送、收支及转化特征对极端降水的影响机制研究。结果表明：通过强盛稳定的台风烟花与中高纬稳定的大气环流形势共同影响下建立的远距离水汽输送通道，使海上的水汽源源不断地被输送到内陆极端降水区。在局地中尺度低值系统产生的动力辐合和迎风坡地形的阻挡作用的共同影响下，远距离输送到极端降水区附近的水汽被有效地汇聚在极端降水区附近，并且依靠低层水汽动力辐合机制，使局地汇聚的水汽被进一步输送至对流层中高层，以此促进对流的发展。在对流上升运动和迎风坡地形抬升作用的共同影响下，通过增强气流的垂直上升运动，使更多的水汽被输送到对流层中高层，促使水汽向云冰粒子和雹粒子的凝华转换过程增强，最终导致降水效率得到显著提升，降水效率在地形迎风坡处显著增强表征的水汽向雨水的高效转化，对极端降水的演变起到了极好的指示作用。上述研究不仅系统性揭示了暴雨多尺度系统影响下极端降水区内局地水汽的主要来源与消耗过程，而且从水汽诊断的角度加深了对极端降水发生机理的认识。
Abstract:Targeting the severe torrential rain process in Henan Province on 20 July 2021, this paper focuses on revealing the features of the water vapor transport, the budget of water vapor flux and the transformation of water vapor as well as the associated impact on the variation of local precipitation based on FNL reanalysis data, gauge precipitation data and high-resolution simulation results. The results show that the water vapor over the ocean was continuously transported to the severe precipitation area by the water vapor channel built by the synergistic effect between the powerful and quasi-stationary Typhoon In-Fa over the East Sea and the stable atmospheric circulation pattern in the middle and high latitude zone. Then the local water vapor constrained within the extreme precipitation area was further transported from the low level to the middle and high level depending on the dynamical convergence mechanism in the low-level troposphere, which was dominated by the mesoscale synoptic system and the blocking effect of the windward slope. The vertical transport of the water vapor was indeed favorable for the reinforcement of the convection in the extreme precipitation area. Finally, under the synergistic effect of the convective ascending motion and the orographic lifting mechanism of the windward slope, more water vapor was vertically transported to the middle and higher troposphere by the reinforced vertical airflow, which stimulated the desublimation process between the water vapor and the ice-phase particles, resulting in the remarkable increase of the precipitation efficiency. The remarkable increase of the precipitation efficiency within the windward slope region was directly responsible for the occurrence of the severe torrential rain in the perspective of microphysical processes. This paper not only comprehensively reveals the main source and the consumption process of the local water vapor dominated by the muti-scale synoptic system in the extreme precipitation event, but also advances the understanding to the occurrence mechanism of the extreme precipitation.
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基金项目:国家自然科学基金面上项目（41975058）、国家自然科学基金青年基金项目（42105010、41705019、42105012）、国家自然科学基金气象联合基金项目（U2142202）和浙江省自然科学基金项目（LQ20D050001）共同资助
引用文本：
李超,崔春光,徐慧燕,王晓芳,李艳,汪小康,许发雷,高媛,2022.河南“21·7”特大暴雨水汽输送、收支和转化特征对局地强降水的影响机制研究[J].气象,48(12):1497-1511.
LI Chao,CUI Chunguang,XU Huiyan,WANG Xiaofang,LI Yan,WANG Xiaokang,XU Falei,GAO Yuan,2022.Characteristics Associated with the Transport, Budget, Conversion of Water Vapor and Their Impact on Localized Precipitation During the Henan Severe Torrential Rain Event on 20 July 2021[J].Meteor Mon,48(12):1497-1511.
李超,崔春光,徐慧燕,王晓芳,李艳,汪小康,许发雷,高媛,2022.河南“21·7”特大暴雨水汽输送、收支和转化特征对局地强降水的影响机制研究[J].气象,48(12):1497-1511.
LI Chao,CUI Chunguang,XU Huiyan,WANG Xiaofang,LI Yan,WANG Xiaokang,XU Falei,GAO Yuan,2022.Characteristics Associated with the Transport, Budget, Conversion of Water Vapor and Their Impact on Localized Precipitation During the Henan Severe Torrential Rain Event on 20 July 2021[J].Meteor Mon,48(12):1497-1511.
