南极长城站雪暴的个例研究

综合使用NCEP分析、站点观测、地面天气图及卫星云图等资料，从地面和高低空天气形势、气象要素变化、大气垂直和水平结构等方面对南极长城站的一次强雪暴天气过程进行了分析研究。该雪暴发生于2006年8月29日，极大风速33.3ms-1，最低水平能见度不足10m。分析认为本次过程发生在“南高北低”的天气形势下，“南高北低”引发的偏东大风是雪暴发生的先决条件。来自南极内陆冷空气的低空东风急流给长城站带来了显著的降温、减湿，使本次雪暴带有明显的低温低湿特征。高空暖平流输送为雪暴的发生提供了充足的水汽条件。中低层深厚的气旋性涡度，高空辐散、低层辐合的散度场配置和强烈的上升运动导致高层暖湿气流和低层干冷气流的充分混合，是导致长城站出现强降雪、进而引发雪暴的动力原因。雪暴后期伴有明显的低层逆温，其本质是上暖下冷的气团垂直结构，它对雪暴后期的维持可能起着重要作用。

A CASE STUDY ON BLIZZARD WEATHER AT GREAT WALL STATION,ANTARCTICA

A blizzard case at Great Wall Station was studied using data of NCEP analysis, in-site observations, surface weather charts and statellite images. The blizzard weather took place on August 29th,2006, and resulted in highest wind speed (33.3m/s) and the worst horizontal visibility (<10m). It’s found that this blizzard was under the situation of ‘High in the south, low in the north’, and the easterly gale caused by the weather situation was the precondition to the blizzard occur. The low level easterly jet from the Antarctic continent brought significiant decrease in air temperature and humidity, made the blizzard with obvious feature of low temperature and humidity. The warm air advection at high levels brought enough mositure from lower latitudes. The deep cyclonic vorticity at middle and low level, the pattern of divergence at high level and convergence at low level, and strong vertical uplifts were the dynamic reason of the strong snowfall and blizzard. There was a inversion layer in the low atmospheric level during the later half of the case which essential was the air mass vertical structure of “cold at low level, warm at high level”, it’s very important to the lasting of the blizzard.