用轨迹法研究寒潮个例

A CASE STUDY OF COLD WAVE IN EAST ASIA USING TRAJECTORY TECHNIQUES

本文利用FGGEⅢ_bSOP(Ⅰ)资料,计算了1979年1月24日—31日的一次东亚寒潮过程中空气质点的三维运动轨迹。结果表明:这例寒潮高压不是原来在欧亚交界处的早期冷高压的东移加强而成,而是在后者的前部巴尔喀什湖及其附近地区再发展而成。整个寒潮酝酿过程实质是一次地面冷高压的替换过程。根据轨迹分析,这例寒潮高压的形成主要是由于在亚马尔半岛及其附近地区对流层中层具有极地冷空气特性的气团南下、到巴尔喀什湖及其附近地区的堆积;同时,这一地区空气本身的绝热上升冷却也起到一定的作用。寒潮爆发阶段,冷空气主体自对流层低层作扇形散开。冷空气的整个活动过程是堆积—散开—再堆积—再度散开的过程。

By using the data of FGGE Ⅲ SOP(Ⅰ), the three-dimensional trajectorie of air parcels in a East Asia cold wave case occurring during 24 Jan. -31 Jan. 1979 are calculated and analysed. The results show that: the cold wave high, over Balchas Lake and its neighbouring region (Area B), did not generate from the upstream cold high (named early stage cold high), which developed in the juncture of Europe and Asia and moved slowly eastward. The cold wave high f ormed and developed as the cold air in polar region around Jamal Peninsula moved down southward to Area B and amassed over there. Furthermore, adiabatic cooling of ascending air over Area B facilitated the formation of the cold wave high. During cold wave breaking out period, the cold air parcels scattered in shape of so called 'sector spread' in the lower troposphere. The whole process of cold air movement in this event is characterized by amassing, scattering, amassing again and scattering again.