Slow oscillations in an ocean of varying depth Part 2. Islands and seamounts
Slow oscillations in an ocean of varying depth Part 2. Islands and seamounts
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不同深度海洋中的缓慢振荡第 2 部分：岛屿和海山
DOI：
10.1017/s0022112069000486
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发表时间：
1969
影响因子：
3.7
通讯作者：
P. Rhines
中科院分区：
文献类型：
--
作者：
P. Rhines
我们考虑慢振荡轴对称岛屿和海山。ω在[lsim ] δ/2的范围内（ω是频率除以f，即科里奥利参数，δ是深度的分数变化）。例如，对于一个有倾斜“裙”的岛屿，周期为[gsim ] 2·4天，h [vprop ] r½，其中h是深度，（r，θ）是与平均海面相切的平面上的极坐标。能量在Rossby波中慢慢地从地形中泄漏。在极限情况下，一个圆柱形的岛屿与垂直的墙壁有没有这样的被困的运动，但入射Rossby波散射各向异性。如果岛半径a与Rossby波长之比γ很小，散射截面为γ3a。在海山和有裙板的岛屿上的自由振荡，当其频率之一接近入射波的频率时，允许更强的散射（横截面为λ a/γ，λ a波长）。该理论表明，在小岛屿上测量罗斯贝波是可能的，但在同一频率范围内的许多本地振荡会增加一些混乱。
We consider slow oscillations trapped about axisymmetric islands and seamounts. ω is in the range [lsim ] δ/2 (ω is the frequency divided by f, the Coriolis parameter, and δ the fractional change in depth). The periods, for example, are [gsim ] 2·4 days for an island with a sloping ‘skirt’, h [vprop ] r½, where h is the depth and (r, θ) are polar co-ordinates in the plane tangent to the mean sea surface. Energy leaks slowly away from the topography in Rossby waves. In the limiting case of a cylindrical island with vertical walls there are no such trapped motions, but incident Rossby waves are scattered anisotropically. If γ, the ratio of the island radius, a, to the Rossby wavelength, is small, the scattering cross-section ∼ γ3a. The free oscillations at seamounts and islands with skirts allow much stronger scattering (with cross-section ∼ a/γ, ∼ a wavelength), when one of their frequencies is near that of the incident wave. The theory suggests that measurements of Rossby waves will be possible at small islands, but that the many local oscillations in the same frequency range will add some confusion.