| 大西洋阻塞高压上层冷中心的成因 |
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| 引用本文： | 马继望,梁湘三.大西洋阻塞高压上层冷中心的成因[J].大气科学学报,2020,43(3):469-480. |
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| 作者姓名： | 马继望 梁湘三 |
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| 作者单位： | 山东省气象台,山东济南250031;南京信息工程大学大气科学学院,江苏南京210044;南京信息工程大学大气科学学院,江苏南京210044;南京信息工程大学海洋科学学院,江苏南京210044 |
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| 基金项目： | 国家自然科学基金资助项目（41975064；41475038）；山东省气象局青年基金项目（2018SDQN02） |
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| 摘 要： | 基于ERA-40再分析资料以及多尺度子空间变换和多尺度能量分析方法,探讨了大西洋阻塞高压平流层底部冷中心的形成机制,发现该冷中心形成的根本原因为16 d以下(高频尺度)和64 d以上过程(基本气流)向阻高尺度有效位能的正则传输,所获得有效位能在阻高尺度内被输运到西北和东南侧,并转换成动能,起到使阻高强度增加或者维持的作用。这种过程在西北侧表现得尤为明显,这可能是阻高形态不断向西北侧扩展的原因。在传统的认知中,大气有效位能从大尺度向小尺度传输,但本研究发现,阻高发生时,有效位能在平流层底部的传输方向表现为从高频尺度和基本气流尺度同时向阻高尺度传输。此外,前人的研究表明,阻高发展加强之后对流层中阻高动能向有效位能转化使得阻高消亡,而本文的分析表明两种能量的转换方向在平流层底部完全相反——由有效位能向动能转换,起到了使阻高加强或维持的作用。最近的研究表明对流层顶附近的动力学对于阻高的发展和维持非常重要,上述发现增进了对这些动力学深层的了解。
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| 关 键 词： | 阻塞高压 冷中心 多尺度过程 多尺度子空间变换 正则传输 |
| 收稿时间： | 2017/6/1 0:00:00 |
| 修稿时间： | 2017/6/15 0:00:00 |
On the formation of the upper cold center of the Atlantic blockings |
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| MA Jiwang and LIANG Xiangsan.On the formation of the upper cold center of the Atlantic blockings[J].大气科学学报,2020,43(3):469-480. |
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| Authors: | MA Jiwang and LIANG Xiangsan |
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| Institution: | Shandong Meteorological Observatory, Jinan 250031, China;School of Atmospheric Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, China and School of Atmospheric Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, China;School of Marine Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, China |
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| Abstract: | Using a new methodology,namely,Multiscale Window Transform(MWT),and the MWT-based multiscale energetics analysis,the cold center of the Atlantic blockings in the lower stratosphere is studied for an understanding of its generation mechanism. It is found that the generation is due to the canonical transfer of Available Potential Energy(APE) to the blocking scale window from both the processes shorter than 16 days and those longer than 64 days; the gained APE is then transported away northwestward and southeastward,and then converted into the blocking-scale Kinetic Energy(KE),causing the enhancement or persistence of the high-pressure centers.These processes are particularly conspicuous in the northwest,which could account for the northwestward extension of the blocking highs.Traditionally it is believed that,in the atmosphere,APE is transferred downward from large scale to smaller scales,but here we find that,when blockings occur,both the low-frequency and high-frequency processes transfer toward the blocking-scale window.Also,different from the previous finding that,in the troposphere the blocking-scale KE is converted into the APE on the same scale window to make the blocking decay,here in the lower stratosphere the conversion is in the opposite direction,i.e.,it is from APE to KE,making the blockings enhanced. Recent numerical experiments indicate that the dynamical processes around the tropopause are crucial for the development and maintenance of the blockings;this study will facilitate a deeper understanding of these processes. |
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| Keywords: | blocking high cold center multiscale processes multiscale window transform canonical transfer |
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