A numerical analysis of a squall line case influenced by northwest cold vortex over Yangtze and Huai River Basin
Yang Ji
(Jiangsu Institute of Meteorological Sciences)
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投稿时间:2018-05-24    修订日期:2019-12-26
中文摘要: 利用四维变分同化分析系统模拟和雷达拼图资料分析了2012年5月16日东北冷涡影响下的弱飑线过程,结果表明:(1)较强的地面辐合线是这一次过程在较弱稳定条件下触发的重要原因,而地面辐合的持续维持也是系统前期快速发展的重要原因;(2)冷池形成之后,垂直风切变方向不垂直于系统,且切边值大小较弱,造成它们形成的水平涡度不平衡,是该系统发展较弱的主要原因,此外不稳定条件和湿度条件较差也可能是系统没有发展为强飑线的原因。
中文关键词: 飑线  东北冷涡  模拟
Abstract:Use Four-Dimensional Variational Doppler Radar Data Assimilation System simulation and radar mosaic data to analyze a weak squall line influenced by northwest cold vortex on 16 May, 2012. The result shows that: (1) Strong convergence line on the ground was an important factor causing convective initial under the weak hydrostatic instability, was also an important reason for quickly developing at the early stage; (2) cold air was continuously carried to Yangtze and Huai River Basin under the control of northwest cold vortex. Because of precipitation dragging by convection within squall line, the dry and cold air was entrained into convection and continuously moving downward, causing strong cold pool due to effect of evaporation. (3) The main reason for weak squall line is that after the cool pool formation, vertical wind shear was not perpendicular to the squall line and weak magnitude, causing imbalance between them. Besides, weak hydrostatic instability and low relative humidity were part of reason for weak squall line. The major difference between this case and other squall lines in eastern China is the strong convergence line and relative dry environment, causing less moisture content deliver to middle level and less latent heating. Finally, upward motion is more depend on balance between cool pool and vertical wind shear. Key words: squall line; northwest cold vortex; simulation
文章编号:201805240232     中图分类号:    文献标志码:
杨吉,0.[en_title][J].Meteor Mon,():-.
Yang Ji,0.A numerical analysis of a squall line case influenced by northwest cold vortex over Yangtze and Huai River Basin[J].Meteor Mon,():-.