中国南方雨雪冰冻异常天气原因的分析  

Cause of Severe Weather with Cold Air,Freezing Rain and Snow over South China in January 2008

作　　者：李崇银[1] 杨辉[2] 顾薇[2] 

机构地区：[1]中国人民解放军理工大学气象学院,南京211101 [2]中国科学院大气物理研究所大气科学和地球流体力学国家重点实验室,北京100029

出　　处：《气候与环境研究》2008年第2期113-122,共10页Climatic and Environmental Research

基　　金：中国科学院创新项目ZKCX3-SW-22;国家重点基础研究规划项目2006CB403600

摘　　要：2008年1月我国南方发生了罕见的持续严重雨雪冰冻灾害,对于这次小概率极端天气气候事件的初步分析表明,虽然这个冬季在赤道东太平洋存在明显的La Nia事件,但2008年1月无论是我国的异常降水场和温度场,还是亚洲和西太平洋地区的大气环流异常场都与历史上11个La Nia事件盛期1月的合成场有显著的差别,因此La Nia事件不是造成持续雨雪冰冻天气的直接罪魁祸首。进一步的分析发现这次持续严重雨雪冰冻天气的发生与多个大气环流系统的异常有关,而且更为重要的是它们的异常形成了某种形式的配合,我们称其为组合性异常。其中,乌拉尔山阻塞高压和贝加尔湖-巴尔喀什湖的横槽,为不断有冷空气从西路向南爆发提供了条件;东亚和日本地区的高度正异常使得北方冷空气的势力不是很强,适于锋面在我国南岭及其以北地区较长时间停留,为持续降水确立了背景;西太平洋副高偏强和偏西也对冷空气的向南推进起了阻挡作用;印缅槽的持续偏强和西太平洋副高的偏强一起使暖湿空气源源不断地输送到华南地区,有利持续降水的发生;持续的冷空气活动和持续的降水,导致持续的低温,为冰冻创造了条件。可以认为,大气环流的组合性异常是造成持续雨雪冰冻天气的直接原因。Lasting disaster weather with cold air,freezing rain and snow occurred over South China during January 2008.This little probabilistic extreme weather and climate event is analyzed.Although La Nia event in the eastern equatorial Pacific is clear in 2007/2008 winter,both the anomalous patterns of the precipitation and temperature in China and atmospheric circulation over Asia and the western Pacific during January 2008 are very different from that of the 11 cases mean for La Nia mature phase in January.Thus La Nia event is not the direct arch-criminal to cause the extreme weather.Further study shows that the occurrence of this lasting disaster weather with cold air,freezing rain and snow is related to the anomalies of the atmospheric circulation systems.These anomalous circulation systems form a kind of cooperation,which is named combination anomaly.In the combination anomaly,the Ural blocking high and a transverse trough from Lake Baikal to Lake Balkhash offer condition for continual cold air pouring southward from the west passage.The positive height anomalies over the eastern Asia and Japan weakens the force of cold air from the north.Thus the front stays over the South Mountain and north of it for a longer time,which establishes background for continuous raining and snowing.Meanwhile,the Northwest Pacific subtropical high extends westward and its intensity is also enhanced.So it blocks the cold air.The persistent strong Indian and Burma trough and the Northwest Pacific subtropical high transport the warm and wet air to South China continuously,which is favorable to the occurrence of continuous rain and snow.Persistent cold air activity and precipitation induce persistent low temperature,which conditions freezing weather.It may be considered that the combination anomaly of the atmospheric circulations is the efficient cause of lasting disaster weather with cold air,freezing rain and snow.

关 键 词：持续雨雪冰冻天气 大气环流组合性异常 LaNia事件 

分 类 号：P434[天文地球—大气科学及气象学]