一次北半球中高纬度地区冬季气象灾害分析

利用NOAA和NCDC原始资料,诊断分析了2007—2008年一次冬季大规模冰冻雨雪灾害天气,重点讨论了各地的阻塞高压(下称阻高)与这次灾害性天气产生原因之间的联系,并通过Rossby波的传播和发展对阻高的影响,分析了阻高产生的原因及在这次天气过程中的作用。结果表明,乌拉尔山阻高和鄂霍次克海阻高的共同作用,阻挡了来自极地冷气流的大股南下,使得来自北方的小股冷空气被阻高分离,南支气流南下与来自副热带高压的暖湿气流交汇,造成降温和持续性降雪,而随着冷平流的输入使阻高原地崩溃,东欧暖平流使阻高西侧新生高压脊发展成新的阻高。北美阻高随着地形作用也导致2007年底美国大部分地区和加拿大东部地区遭受暴风雪的袭击。Rossby波的传播与演变促使了阻高的形成,极涡南移过程中也造成这些地区的大雪和暴雪,阻高的调整(崩溃和重建)导致强冷空气的爆发。

Analysis on Climatic Disaster in Winter in Middle and High Latitude Regions of Northern Hemisphere

The large-scale disastrous frozen weather caused by heavy rain and snow in the winter from 2007 to 2008 was diagnosed and analyzed.The relationship between the blocking high and the disastrous weather was mainly discussed.According to the influence of the transmission and development of Rossby wave on the blocking high,the appearing reason of the blocking high and its function in the weather process were analyzed.The results indicate that a little current of cold air go down south common action of Ural and Okhotsk Sea blocking highs,and cause a widespread drop of temperature and lasting snow when the southern cold air meet with warm airflow from Subtropical High in the Western Pacific.Blocking high collapseswith the transportation of cold air stream,a new blocking high locatesto the west of blocking high with the transportation of warm advection.Moreover,the blocking high in North America leads to the snowstorm in most region of America and eastern part of Canada in the end of 2007 as well.The propagation and evolution of Rossby wave promote the formation of blocking high,and polar vortex also causessnow and blizzard in these areas.The restructure of the blocking high(collapses and reconstruct) leads to the onset of strong cold air.