Lateral Coupling in Baroclinically Unstable Flows
Lateral Coupling in Baroclinically Unstable Flows
复制标题
斜压不稳定流中的横向耦合
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
J. Pedlosky
中科院分区：
文献类型：
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作者：
M. Spall;J. Pedlosky
摘要 采用通道内两层准地转模型研究不同符号平均位涡梯度(Πy)区域的横向位移对线性不稳定波的生长速率和结构的影响。平均状态非常理想化，上层有正 Πy 区域，下层有负 Πy 区域；其他地方 Πy 为零。模型不稳定波的增长率和结构对两个区域之间的重叠量非常敏感。对于大量重叠（超过几个内部变形半径），可以恢复菲利普斯模型描述的通道模式。随着重叠量减少到内部变形半径以下，增长率急剧下降。然而，对于两个非零 Πy 区域相距较远的情况，也会发现不稳定模式。在这些情况下，不稳定波的波数减少，使得波的纵横比保持为 O(1)。波浪的特点是...
Abstract A two-layer quasigeostrophic model in a channel is used to study the influence of lateral displacements of regions of different sign mean potential vorticity gradient (Πy) on the growth rate and structure of linearly unstable waves. The mean state is very idealized, with a region of positive Πy in the upper layer and a region of negative Πy in the lower layer; elsewhere Πy is zero. The growth rate and structure of the model’s unstable waves are quite sensitive to the amount of overlap between the two regions. For large amounts of overlap (more than several internal deformation radii), the channel modes described by Phillips’ model are recovered. The growth rate decreases abruptly as the amount of overlap decreases below the internal deformation radius. However, unstable modes are also found for cases in which the two nonzero Πy regions are separated far apart. In these cases, the wavenumber of the unstable waves decreases such that the aspect ratio of the wave remains O(1). The waves are characte...