北太平洋冬季天气尺度涡旋对大气低频变化的作用

项目名称： 北太平洋冬季天气尺度涡旋对大气低频变化的作用

项目编号： No.41475070

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 谭言科

作者单位： 中国人民解放军陆军工程大学

项目金额： 84万元

中文摘要： 近十年来的研究表明，行星尺度的低频流和天气尺度的涡旋是互相依赖的，这种依赖被认为是这两种不同类型气流的共生关系，它们之间的相互作用在低频变率主要模态的形成中起重要作用。然而，这种中纬度低频变化产生的机制目前尚不完全清楚。本项目拟以北太平洋冬季高空西风急流、斜压波和低频变化模态的关系为框架，以天气涡旋对低频变化的作用为研究核心，综合运用诊断分析、动力学分析和数值模拟的方法，弄清低层天气涡旋异常通过影响海气热通量继而影响低层大气斜压性的事实，分析大气低频变化过程中斜压波包的能量转换、与非地转风相联系的扰动位势高度通量、气旋式和反气旋式Rossby波破碎，研究相对应的瞬变动量通量的异常辐合辐散，明确天气涡旋活动产生低频变化的动力反馈本质。通过这些研究，揭示天气涡旋作用低频变化的具体过程和物理机制，理解北太平洋大气环流异常的独特性。

中文关键词： 天气尺度涡旋；大气低频变化；能量转换；Rossby波破碎

英文摘要： During the last decade,investigations demonstrated that planetary low-frequency flow and synoptic eddy flow depend on each other, which was considered to be a symbiotic relation between the two different kinds of flow variability. The synoptic eddy and low-frequency flow mutual interaction is recognized as playing an essential role in generating the dominant modes of the low-frequency variability. However, the fundamental mechanism for extratropical low-frequency variability is still not fully understood. This project is based on the framework conjunction among wintertime westerly jet, baroclinic wave and low-frequency modes over the North Pacific, and it focuses on the role of synoptic eddy on the low-frequency variability. The process that synoptic eddy may influence the atmospheric meridional temperature gradient via air-sea heat flux, the energy conversions between the baroclinic wave packet and low-frequency flow, the geopotential height perturbation flux associated with ageostrophic wind, the cyclonic and anti-cyclonic Rossby wave breaking together with the anomalies of synoptic eddy momentum flux convergence will be investigated by diagnostic analysis, dynamical studies and model simulation. Therefore, the essential dynamical feedback of the synoptic eddy activity on generating the low-frequency pattern can be well understood. Through the studies, we hope to elucidate the process and mechanism in details of synoptic eddy's role on low-frequency variation, and understand the special characteristics of atmospheric circulation anomalies over the North Pacific.

英文关键词： Synoptic-scale Eddy;Atmospheric Low-frequency Variability;Energy Conversion;Rossby Wave Breaking