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在地形上方的二维流:旋和潜在的旋同质化
Lia Siegelman1, William R Young1
1Scripps Institution of Oceanography, University of California, San Diego, CA 92093.
概括
在粗的地形上的二维流会呈现出不同的高能和低能状态. 高能量会导致旋驱动的混合和潜在旋 (PV) 均质化,而低能量会导致地形锁定的旋和保留的PV变化.
科学领域:
- 流体动力学 流体动力学
- 地质物理学 地质物理学
- 流理论是关于流的.
背景情况:
- 在地形上的二维流表现出基于初始运动能量的两个不同的状态.
- 在高能量状态下,地形表现为弱扰动,导致 vortex 形成和潜在 vorticity (PV) 同质化.
- 在低能耗模式下,旋会被锁定在地形特征上,从而保留光伏的空间变化.
研究的目的:
- 开发一个统一的框架,以了解不同能量级别的地形流.
- 确定分离高能和低能流演变的临界动能值.
- 阐明驱动光伏同质化或在随机粗地形上的2D流中保持光伏同质化的机制.
主要方法:
- 在随机粗地形上进行非强制性,弱度减弱的2D流的数值模拟.
- 分析旋动力学,动能水平和潜在旋 (PV) 分布.
- 开发一个理论框架来统一观察到的动荡状态.
主要成果:
- 确定了高能 (主导,光伏同质化) 和低能 (地形锁定,光伏变化) 模式之间的明确区别.
- 一个临界动能水平, [公式:参见文本],被确立为这两个状态之间的分离器.
- 该框架统一了对地形动荡的理解,强调光伏均化作为一个关键的结果,取决于能源水平.
结论:
- 流动的能量水平是地形上的二维流演变的关键决定因素.
- 由于强烈的相互作用,在高能流中可以实现光伏均质化,而低能流则导致受地形影响的光伏结构.
- 开发的框架提供了对地形动荡的全面理解,弥合了以前观察到的极端状态.
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