| 东亚春季强冷锋结构及其动力学诊断研究 II. 动力学诊断研究 |
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| 引用本文： | 李振军,赵思雄.东亚春季强冷锋结构及其动力学诊断研究 II. 动力学诊断研究[J].大气科学,1997,21(1):91-98. |
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| 作者姓名： | 李振军 赵思雄 |
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| 作者单位： | 1.空军气象中心,北京100843 |
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| 基金项目： | 本研究工作得到国家自然科学基金课题(49575257)的资助 |
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| 摘 要： | 在本文第I部分对东亚春季强冷锋结构进行分析的基础上，第II部分对该锋面的增强过程作了动力学诊断的研究。通过研究发现:(1)从27日08时至28日20时（北京时，下同），该冷锋处于加强阶段，锋生函数的计算显示，最大锋生区出现在对流层中层，各项的量级相同，但以倾斜项的数值为大；(2)在锋生区的南侧发现有很明显的条件对称不稳定（CSI）区域，这有利于倾斜的对流上升运动的发展，提供了一个较好的强对流系统发展的环境，对冷锋中尺度雨带的形成，CSI的激发可能有重要的作用，然而东亚春季强冷锋的CSI与北美“典型”的CSI有较明显的不同；(3)本例与Hoskins-Bretherton（HB）的理论模型所进行的比较表明，HB模型的结果可说明实际观测到的锋区的基本特征。然而，理论模型中，可能由于采用半地转假设所限，对锋后的一支下沉气流描写较弱，而这支气流对强烈天气的发展可能有重要意义。
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| 关 键 词： | 锋生函数 中尺度雨带 对称不稳定 理论模型 |
A Structure and Dynamics of Cold Fronts Observed in East Asia during Spring. Part II: Dynamics of Strong Spring Cold Front |
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| Li Zhenjun and Zhao Sixiong.A Structure and Dynamics of Cold Fronts Observed in East Asia during Spring. Part II: Dynamics of Strong Spring Cold Front[J].Chinese Journal of Atmospheric Sciences,1997,21(1):91-98. |
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| Authors: | Li Zhenjun and Zhao Sixiong |
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| Abstract: | Based on the analysis of the cold front structure in Part I, the frontogenetical function was computed, conditional symmetric instability was discussed and then, the results of the diagnostic study were compared with Hoskins Bretherton (HB) model. The results are as follows: (1) Comparison of the various terms of frontogenetical function shows their orders are the same and the values of tilting term is larger than the others. In addition, the maxima of the total frontogeneticl function appears in the lower middle troposphere in the development stage of a front. (2) Conditional symmetrical instability has been evaluated. Several regions of CSI can be identified. It was noticed that the low level CSI is almost in same area that of the upward vertical motion (UVM) associated with the direct thermal circulation. Probably, the small moist symmetric instability could strengthen the intensity and decrease the scale of the UVM branch with respect to its vertical displacement. (3) Comparison between this analyses and model results of Hoskins and Bretherton reveals that the main features of the observed front agree qualitatively well with the model prediction. The major difference between the observed and model predicted fronts is that the subsidence in the cold air region is actually stronger than the mode prediction. |
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| Keywords: | frontogenetical function mesoscale rainband conditional symmetric instability theoretical model |
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