Global abyssal mixing inferred from lowered ADCP shear and CTD strain profiles
Global abyssal mixing inferred from lowered ADCP shear and CTD strain profiles
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DOI：
10.1175/jpo2926.1
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发表时间：
2006-08-01
影响因子：
3.5
通讯作者：
Thurnherr, Andreas M.
中科院分区：
文献类型：
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作者：
Kunze, Eric;Firing, Eric;Thurnherr, Andreas M.
内波-波相互作用理论和观测结果支持对取决于内波剪切 [V-z(2)] 和应变 [xi(2)(z)] 方差的湍流耗散率 epsilon 和涡流扩散率 K 进行参数化。其最新版本适用于来自印度洋、太平洋、北大西洋和南大洋的约 3500 个降低的 ADCP/CTD 剖面。推断的扩散系数 K 是纬度和深度的函数，范围从赤道 2 度范围内的 0.03 x 10(-4) m(2) s(-1) 到 50 度 - 70 度范围内的 (0.4 - 0.5) x 10(-4) m(2) s(-1)。在热带和亚热带水域，扩散系数 K 也随着深度的增加而增加。 4500 米深度以下的扩散度在 20 度到 30 度之间呈现出 0.7 x 10(-4) m(2) s(-1) 的峰值，在这些纬度，半日参数次谐波不稳定预计会活跃。湍流是高度异质的。虽然大部分垂直积分耗散积分 (epsilon) 是由主密斜斜贡献的，但积分 (epsilon) 中的热点显示出与小尺度底部粗糙度和近底部流动的某些相关性，这些点处涉及由潮汐 - 地形相互作用引起的强表面潮汐耗散。平均垂直积分耗散率为 1.0 mW m(-2)，比全球平均深海表面潮汐损失 3.3 mW m(-2) 更接近规范（Garrett 和 Munk）内波谱预期的 0.8 mW m(-2)。
Internal wave - wave interaction theories and observations support a parameterization for the turbulent dissipation rate epsilon and eddy diffusivity K that depends on internal wave shear [V-z(2)] and strain [xi(2)(z)] variances. Its latest incarnation is applied to about 3500 lowered ADCP/CTD profiles from the Indian, Pacific, North Atlantic, and Southern Oceans. Inferred diffusivities K are functions of latitude and depth, ranging from 0.03 x 10(-4) m(2) s(-1) within 2 degrees of the equator to (0.4 - 0.5) x 10(-4) m(2) s(-1) at 50 degrees-70 degrees. Diffusivities K also increase with depth in tropical and subtropical waters. Diffusivities below 4500-m depth exhibit a peak of 0.7 x 10(-4) m(2) s(-1) between 20 degrees and 30 degrees, latitudes where semidiurnal parametric subharmonic instability is expected to be active. Turbulence is highly heterogeneous. Though the bulk of the vertically integrated dissipation integral(epsilon) is contributed from the main pycnocline, hotspots in integral(epsilon) show some correlation with small-scale bottom roughness and near-bottom flow at sites where strong surface tidal dissipation resulting from tide - topography interactions has been implicated. Average vertically integrated dissipation rates are 1.0 mW m(-2), lying closer to the 0.8 mW m(-2) expected for a canonical (Garrett and Munk) internal wave spectrum than the global-averaged deep-ocean surface tide loss of 3.3 mW m(-2).