安徽沿江一次连续性暴雨过程中急流特征分析

Analysis of jet characteristic during the persistent heavy rainfall in riverside area in Anhui

利用国家自动气象站和ECMWF-interim再分析资料,从高低空急流的角度对2016年7月1—4日安徽沿江地区的连续性暴雨的成因进行了探讨。研究表明,7月1—4日,高空急流出现明显的北跳、强度增强,低层西南急流强度则达到2016年最大值。伴随着高低空急流的异常变化,在安徽沿江地区上空形成了强烈的高空辐散和低空辐合,同时高低空急流耦合激发形成次级环流,使得旺盛的上升运动一直延伸至对流层上层。高低空急流耦合在1—2日比较强烈,3日起耦合强度逐渐减弱,导致小时雨强进一步减弱。另一方面,低空急流的增强也使得孟加拉湾的水汽源源不断的输送至安徽沿江地区,近地面至3 000 m高度上南风输送为沿江地区连续性暴雨提供了充沛的水汽。

Based on data of national automatic meteorological station and ECMWF-interim reanalysis data,possible causes of persistent heavy rainfall in riverside area in Anhui Province from July 1 to 4,2016 were studied from the aspect of high-and low-level jets. Results show that the strengthened highlevel jet jump northward significantly,while the southwest low-level jet reaches its maximum strength in2016. Along with the abnormal changes of high-and low-level jets,the strong high-level divergence and low-level convergence were formed over the riverside area in Anhui. Coupled high-and low-level jets excite a secondary circulation,resulting in the ascending motion extending to the top of the troposphere.Coupled high-and low-level jets were stronger in July 1—2 and gradually weakened since July 3. Hourly rain intensity shows the similar change. Additionally,the strong low-level jet transported abundant vapor from the Bay of Bengal to the riverside area in Anhui. Especially,the south wind from near surface to the altitude of 3 000 m provides abundant moisture air for the persistent heavy rainfall.