【摘要】 选取2014年4月22日北疆发生大风降温,南疆发生强沙尘暴的一次冷锋过境寒潮天气过程,利用常规气象数据和1度NCEP再分析资料,分析了500 hPa天气形势和地面气压场,计算了冷暖平流、温度梯度和锋生函数,分析了其在水平面以及西北东南向垂直剖面上的三维结构和演变特征。表明:500 hPa偏东位置欧洲脊在暖平流作用下快速向北发展,西西伯利亚槽在冷平流作用下加强并东移南下,受其影响,地面图上锋面气旋发展旺盛,冷空气东移时遇到平均海拔高度3000 m的天山高大陡峭地形,在对流层中下层的水平面上,等温线沿天山密集分布,梯度很大;在垂直剖面图上,天山附近位温线密集,呈带状准垂直分布;同时锋生函数F>0,发生锋生。冷锋在天山北麓位置少动,呈准静止状态。更多还原

【Abstract】 Impacted by a quasi-stationary front,strong winds and temperature decline occurred in northern Xinjiang and a cold front transit cold wave process with strong sandstorm appeared in southern Xinjiang on 22 nd April 2014. By using conventional observation and NCEP reanalysis data,this paper analyzed the 500 hPa synoptic condition and the surface pressure field during this cold wave frontal process, and calculated the cold and warm advection, temperature gradient and frontogenetical function. In addition,the 3-D structure and evolution characteristics of the three physical quantities on horizontal plane and vertical cross-section in the northwest-southeast direction are analyzed. The results suggest that,the 500 hPa European ridge develops quickly northward in the response of warm advection while the West Siberian trough strengthens and moves southward under the influence of cold advection. Affected by this,frontal cyclones develop vigorously on the surface chart.When the cold air moves eastward,it encounters the tall and steep terrain of Tianshan Mountains with an average altitude of 3000 m,and in the middle and lower stratosphere,the isotherms along Tianshan Mountains distribute densely with large gradients. On the vertical cross-section, the potential temperature lines near Tianshan Mountains are very dense,showing a zonal quasi-vertical distribution. Meanwhile,frontogenetical function F>0,which means frontogenesis occurred. The cold front moves little at the northern foot of Tianshan Mountains,showing a quasi-static state.更多还原