2008年初中国南方低温雨雪冰冻事件的等熵位涡分析  

Isentropic Potential Vorticity Analysis on the Events of Low Temperature,Freezing Rain and Snow in Southern China in Early 2008

作　　者：黎惠金[1,2] 李江南[1] 肖辉[3] 蒙伟光[4] 王安宇[1] 

机构地区：[1]中山大学环境科学与工程学院,广东广州510275 [2]广西来宾市气象局,广西来宾546100 [3]中国科学院大气物理研究所云降水物理与强风暴实验室,北京100029 [4]中国气象局广州热带海洋气象研究所,广东广州510080

出　　处：《高原气象》2010年第5期1196-1207,共12页Plateau Meteorology

基　　金：中国科学院知识创新工程领域前沿项目(IAP09308);中国气象局广州热带海洋气象研究所开放基金项目;国家自然科学基金重点项目(40730951)共同资助

摘　　要：利用等熵位涡理论对2008年初发生在我国南方的低温雨雪冰冻事件进行了诊断分析,结果表明,这次低温雨雪冰冻天气事件第一阶段的强冷空气主要来自新地岛以东洋面的平流层下部和对流层上部,从第二到第四阶段除了新地岛以东洋面外,还有来自北欧和拉普帖夫海、地中海的高位涡强冷空气补充。伴随着高层高位涡向南传播,高位涡气块在垂直方向强烈向下伸展、对流层顶动力异常,引起高位涡区气块旋转加强、正涡度增加及其前方低层正涡度的产生,而其后方,因绕高位涡中心气流沿等熵面下沉,地面高压迅速发展,低位涡气块则相反。过程期间,由于巴尔喀什湖高位涡中心和地中海高位涡主体(低涡)的存在和维持,孟加拉湾上空正相对涡度输送频繁,使得南支槽不断生消;而乌拉尔山低位涡带(高脊)和贝加尔湖高位涡中心(低涡)由于低、高位涡空气的不断注入,发生一次次的替换和发展,在引导冷空气持续南下与孟加拉湾北上的暖湿气流长时间在我国华南上空汇合的同时,还导致地面西伯利亚高压反复增强并分裂小高压数次南下,地面强冷空气不断补充,最终造成华南低温雨雪冰冻天气的长时间持续。The isentropic potential vorticity is used to diagnose the events of low temperature,freezing rain and snow in southern China in early 2008.The results show that the strong cold air is mainly from the lower-stratosphere and upper-troposphere on the ocean surface in the east of Novaya Zemlya in the first phase of the low temperature,freezing rain event.From the second to the fourth stages the strong cold air of high potential vorticity added from the Northern Europe,Laptev Sea and the Mediterranean except for the east of Novaya Zemlya.While the high potential vorticity in high layer spread southward,the air parcel of high potential vorticity in the vertical direction was stretching downward tremendously and the abnormal dynamic in the tropopause made the rotating of air parcel in high potential vorticity areas strengthened,positive vorticity increasing and low-level positive vorticity in front of the areas generating.Behind the areas the air flow around the high potential vorticity center was declining down along the isentropic surface,so the high pressure in ground rapidly developed,and the conditions of low potential vorticity were the opposite.During the process,the existence and maintenance of the Balkhash Lake high potential vorticity center and the main body of Mediterranean high potential vorticity（low vortex）,and the frequent transportation of the positive relative vorticity over the Bay of Bengal make for the south branch trough growing and dissipating constantly.The low potential vorticity belts（high ridge） over the Ural Mountains and the high potential vorticity center（low vortex） of Lake Baikal were replaced and developed again and again due to the continuous afflux of high and low potential vorticity.It not only makes the continuously southward cold air and the northward moist warm air from the Bay of Bengal is long-time in convergence over South China,but also causes the Siberian high pressure in ground repeatedly enhance and split into small high pressures to spread southward several tim

关 键 词：中国南方 雨雪冰冻事件 等熵位涡 

分 类 号：P426.63[天文地球—大气科学及气象学]