山东半岛一次强冷流降雪过程的中尺度特征分析

Mesoscale Features Analysis of a Cold-Air Outbreak Snow Storm Event in Shandong Peninsula

利用高空和地面的常规观测和天气加密观测资料，以及MM5V3．6中尺度数值模式系统的模拟结果，对2003年1月3～5日山东半岛北部地区发生的暴雪过程进行了中尺度特征研究。实况资料表明：在高空有利的大尺度环流形势控制下。不断入侵的冷空气作用下，受渤海暖海面的热力作用和山东半岛地形作用，产生了中尺度的海岸锋。在强冷平流、海岸锋锋生及半岛地形的摩擦抬升共同作用下，产生了这次强冷流降雪。海岸锋环流形成的对流云能引起降水量的局部增强。数值模拟结果表明：海岸锋生过程及其产生的沿岸辐合带是形成山东半岛冷流暴雪的主要原因，同时海岸锋同低层大气重力波耦合形成了海岸锋陷波。本文给出了山东半岛北岸海岸锋的概念模型。

Using the satellite data and the routine radio-sound and surface observations as well as some endensifted surface observations and with the results of simulation by mesoscale model-MM5, we study the case of a severe cold-air outbreak snow storm event during 2-5 January 2003 in the northern coastal area of the Shandong Peninsula. Observation data analyses show that a mesoscale coastal front was generated owing to the cooperation for the favorable synoptic circulation and both thermodynamic forcing caused by the warm Bohai-sea surface and dynamic forcing by the topography, which could induce convective clouds and bring an obvious increase of local snowfall. The results of numerical simulation indicate that the process of coastal front frontogenesis and coastal convergence zone are the main reasons for the cold-air outbreak snow storm in the Shandong Peninsula. Meanwhile, the coupling of coastal front with gravity waves generated a less active gravity wave, which was named a wave trapped by coastal front. In this paper we propose a conceptual model for the coastal front north of the Shandong Peninsula.