Inertial Oscillations and Frontogenesis in a Zero Potential Vorticity Model
Inertial Oscillations and Frontogenesis in a Zero Potential Vorticity Model
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零位涡模型中的惯性振荡和锋生
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
W. Blumen
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文献类型：
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作者：
W. Blumen
本文用一个满足零位涡度条件的二维、无粘性、旋转的非线性流体模式研究了地转调节和锋生。流体的顶部和底部由水平的刚性盖子限制。初始状态是没有运动的状态，但规定了一个不平衡的水平温度梯度。随后的运动被表示为具有局部科里奥利频率f的惯性振荡和不断演变的地转流的总和。当一个无量纲参数a，即Rossby数满足a<；1时，演变中的地转流的梯度在0<；t⩽π/f期间增大(锋生)；在π/f<；t⩽2π/f期间减小(锋生)。当≥为1时，演变中的地转流的相对涡度变得无限大：在周期0<；t⩽π/f期间，在顶部和底部边界处形成不连续。在惯性振荡和地转流之间存在能量均分。
Abstract Geostrophic adjustment and frontogenesis are examined by means of a two-dimensional, inviscid, rotating and nonlinear fluid model that satisfies the condition of zero potential vorticity. The fluid is bounded top and bottom by level, rigid lids. The initial state is one of no motion, but an unbalanced horizontal temperature gradient is prescribed. The subsequent motion is represented as the sum of an inertial oscillation, with the frequency of the local Coriolis frequency f, and an evolving geostrophic flow. When a nondimensional parameter a, a Rossby number, satisfies a < 1, the gradient of the evolving geostrophic flow increases (frontogenesis) during the period 0 < t ⩽ π/f; the gradient decreases during the period π/f < t ⩽ 2π/f (frontolysis). When a ≥ 1, the relative vorticity of the evolving geostrophic flow becomes infinite: a discontinuity forms at the top and bottom boundaries during the period 0 < t ⩽ π/f. There is an equipartition of energy between the inertial oscillation and the geost...