陈功,李国平. 2011. 夏季青藏高原低涡的切向流场及波动特征分析[J]. 气象学报, 69(6):956-963, doi:10.11676/qxxb2011.083
夏季青藏高原低涡的切向流场及波动特征分析
Characteristics of the tangential flow field of the Tibetan Plateau vortices and associated waves
投稿时间:2009-08-27  修订日期:2010-03-02
DOI:10.11676/qxxb2011.083
中文关键词:  高原低涡,热力作用,切向流场,涡旋罗斯贝-惯性重力混合波
英文关键词:Tibetan Plateau vortices, Thermal forcing, Tangential flow field, Mixed inertial Gravity Vortex Rossby waves
基金项目:国家自然科学基金项目(40875023,41175045)、国家重点基础研究发展计划(973计划)项目(2012CB417200)和财政部、科技部公益性行业(气象)科研专项(GYHY201206042)
作者单位
陈功 成都信息工程学院大气科学学院和高原大气与环境四川省重点实验室成都610225 
李国平 成都信息工程学院大气科学学院和高原大气与环境四川省重点实验室成都610225 
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中文摘要:
      从大气动力学原理出发,将高原低涡视为受热源强迫的边界层内涡旋,建立了柱坐标下满足梯度风平衡的低涡控制方程组,分析高原低涡切向流场的基本特征。在此基础上,通过求解线性化涡旋模式,得出高原低涡中各类波动的频散关系及其特征,同时定性讨论了热力作用对混合波动的影响以及混合波动与高原低涡流场特征的联系。使用中尺度数值模式WRF分别进行了两次数值模拟实验:一次是理想数值试验,对动力学流场部分的推导加以分析和验证;另一次对2006年8月14日的高原低涡过程进行了三重嵌套的数值模拟,并分析了模拟输出的高时空分辨率资料。研究认为,青藏高原低涡切向流场的特征为:在动力变性高度以下,有气旋性气流伴有辐合,且随高度升高减弱,而高层有反气旋气流伴有辐散,且随高度升高增强。高原热力和边界层作用表现在:当热源径向分布呈现中心加热的形式时,在动力变性高度之下,加热作用将使气旋式流场随时间增强,而在动力变性高度之上,会使反气旋式流场随时间增强;边界层有气旋性气流时,在动力变性高度以下,低涡切向流场加强,若边界层有反气旋性气流时,在动力变性高度以下,低涡切向流场减弱。高原低涡中同时具有产生涡旋罗斯贝波与惯性重力波的条件,热力作用随径向及其梯度的变化对这种混合波动有重要影响。
英文摘要:
      From the dynamic principle, the Tibetan Plateau vortices were assumed as the vortices in the boundary layer forced by diabatic heating and friction. In order to analyze the basic characteristics of tangential flow field of the vortices, the control equations for the vortices were then established in the column coordinate with the balance of gradient wind assumed. Based on this, the type of mixed waves and their dispersion characteristics were deduced by solving the linear model. In addition, the impact of diabatic heating on the mixed waves and the connection of mixed waves with the characteristics of flow field of the vortices were qualitatively discussed. Two Numerical simulations were also done by the WRF which was developed by the NCEP/NCAR. Among them one is an idealized large eddy simulation whose aim was to validate the tangential flow field deduced from the control equations. The other is the simulation of a Tibetan Plateau vortex on August 14, 2006 using the WRF with triple nested domains employed. The high resolution model output data were than analyzed. The results show that the tangential flow field of the Tibetan Plateau vortices is cyclonic convergence below the critical height and the intensity weakened with height, while there are anti cyclonic divergence flows above the critical height and the intensity increased with height. When the heating field is in the form of center heating, the cyclonic tangential flows increased with time below the critical height and the anti cyclonic tangential flow increased with time above the critical height; the intensity of the tangential flow field is increased below the critical height when there are cyclonic flows in the boundary layer, and the intensity of tangential flow field is decreased below the critical height when there are anti cyclonic flows in the boundary layer. The Tibetan Plateau vortices may contain the mixed Inertial Gravity Vortex Rossby waves and changes in the heating with radial and its radial gradient variation will have great impact on the mixed waves.
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