“16·7”华北极端强降水特征及天气学成因分析  

Characteristics and Synoptic Mechanism of the July 2016 Extreme Precipitation Event in North China

作　　者：符娇兰 马学款 陈涛 张芳 张夕迪 孙军 权婉晴 杨舒楠 沈晓琳 

机构地区：[1]国家气象中心,北京100081

出　　处：《气象》2017年第5期528-539,共12页Meteorological Monthly

基　　金：中国气象局预报员专项(CMAYBY2016-086);国家自然科学基金项目(41105030);预报预测核心业务发展专项(CMAHX20160101)共同资助

摘　　要：2016年7月19-20日华北出现了当年入汛以来最强降水过程。此次降水过程为一次影响范围广、累积雨量大、持续时间长的极端强降水过程,其强度较"96·8"强,仅次于"63·8"。以暖云降水为主,短时强降水特征明显,局地小时雨强强、且具有明显的地形降水特征。此次强降水发生在南亚高压东伸加强、副热带高压西伸北抬、中高纬度西风带低涡系统发展的环流背景下,黄淮气旋、西南和东南低空急流的异常发展以及水汽的异常充沛表明此次强降水过程动力抬升和水汽条件非常有利。强降水过程表现出明显的阶段特征,主要分为两个阶段:19日凌晨至白天为高空槽前偏东风导致的地形强降水、19日夜间至20日为黄淮气旋系统北侧螺旋雨带造成的强降水。第一阶段的降水主要与高空槽前偏东风/东南风急流的发展有直接关系。这一阶段对流降水旺盛,中层弱干冷平流以及低层强暖平流是对流不稳定能量的维持机制,强降水形成的冷堆与局地地形作用产生的中尺度锋生过程为对流持续新生提供了有利条件。第二阶段的降水主要与低涡切断和黄淮气旋的强烈发展有关。该阶段降水对流相对较弱,黄淮气旋进入华北以后移动缓慢,从而造成降水持续时间较长。An extremely severe precipitation event took place in North China in 19--20 July 2016. It was characterized by large rainfall, persistent rainfall, warm cloud rainfall, strong local rainfall intensity and orographie precipitation. Its rainfall was larger than that of the extreme rainfall in 3--5 August 1996, and only next to the amount of the 2--7 August 1963 extreme rainfall event. It occurred under the circulation background of the South Asia high moving eastward, the West Pacific subtropical high moving northwest- ward and the low vortex in the westerlies developing in mid-high latitude. The abnormal development of Huanghuai cyclone, southwest and southeast low-level jets, and the abnormally abundant moisture indi- cates that the dynamic lifting and moisture conditions favored this severe rainfall process significantly. The whole rainfall event presented clearly the phase characteristics, and could be divided into two stages. The first stage was the orographic rainfall caused by the easterly winds ahead of the trough from the early morning to the daytime of 19 July, while the second part was produced by spiral rain bands in the north side of Huanghuai cyclone from the night of 19 to the daytime of 20 July. In the first stage, the easterly low-level jet was lifted by the Taihang Mountains, which continuously triggered the convective cells along the east edge of the mountains. The weak dry and cold advection at mid-level and the strong warm and wet advection at low-level jointly maintained the convective instability. The cold pool generated by heavy rain- fall and the mesoscale frontogenesis process created by local orographic effect provided favorable conditions for severe convections to occur continuously. The second stage rainfall was mainly related to the develop- ment of cut-off vortex and Huanghuai cyclone. The blocking of the high pressure system slowed the steps of Huanghuai cyclone in North China, thus leading to the long-lasting rainfall process.

关 键 词：极端降水事件 切断低涡 异常发展 移动缓慢 地形增幅 

分 类 号：P458[天文地球—大气科学及气象学]