三峡坝区一次冬季持续性晴空大风的成因分析  

Analysis on the causes of a continuous clear-sky gale event in winter in the Three Gorges Dam Area

作　　者：范元月 张家国[2] 枚雪彬 李洪兵 丁丽丽 FAN Yuanyue;ZHANG Jiaguo;MEI Xuebin;LI Hongbing;DING Lili(Yichang Meteorological Office of Hubei Province,Yichang 443000;Wuhan Central Meteorological Observatory,Wuhan 430074)

机构地区：[1]湖北省宜昌市气象局,宜昌443000 [2]武汉中心气象台,武汉430074

出　　处：《暴雨灾害》2022年第2期184-191,共8页Torrential Rain and Disasters

基　　金：湖北省气象局科技基金项目(2020J03);水利部三峡库区局地气候监测项目(SK2019027)。

摘　　要：2021年1月中旬,三峡坝区出现了一次严重影响近坝区通航安全的持续性晴空大风过程(以下简称“21·1”坝区晴空大风)。使用常规观测资料及中尺度观测资料等,应用天气学分析和诊断方法,分析了“21·1”坝区晴空大风时空分布特征及其成因。结果表明:此次晴空大风发生在背风坡河谷地带,大风期间存在4次风速波动,夜间风速大于白天;地面大风由边界层动量下传导致,动量来源于低层急流,下沉运动与大振幅背风波有关。边界层垂直风切变和逆温层的稳定存在使背风波持续时间增长,逆温层下较大的温度垂直递减率进一步加强了下沉运动,是晴空大风形成并持续的主要成因。A continuous clear-sky gale event(hereinafter referred to as“21·1”clear-sky gale in the dam area)occurs in the Three Gorges Dam Area in the middle January of 2021,which seriously affected the navigation safety of the Yangtze River near the dam area.Using rou⁃tine upper-air and surface observations,mesoscale observational data and other data,we have applied the weather analysis and dynamic di⁃agnostic methods to analyze the spatial-temporal distribution characteristics and the causes of“21·1”clear-sky gale in the dam area.The results show that this clear-sky gale event occurred in the valley under the leeward slope,and there are four wind speed fluctuations during the whole event,whose wind speed at night is greater than that in the daytime.The ground gale is caused by the momentum downward-trans⁃portation in the boundary layer,which is derived from the low-level jet.The aforementioned descending motion causing the ground gale is re⁃lated to the lee wave with large amplitude.During this clear-sky gale event,the steady vertical wind shear and inversion layer in the bound⁃ary layer make the lee wave last for a long time,and the greater vertical declining rate of temperature under the inversion layer further strengthens the descending motion,which is the main reason why the“21·1”clear-sky gale in the dam area forms and continues.

关 键 词：晴空大风 动量下传 背风波 逆温层 三峡坝区 

分 类 号：P458.123[天文地球—大气科学及气象学]