Internal-Wave-Driven Mixing: Global Geography and Budgets
Internal-Wave-Driven Mixing: Global Geography and Budgets
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DOI：
10.1175/jpo-d-16-0141.1
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发表时间：
2017-06-01
影响因子：
3.5
通讯作者：
Kunze, Eric
中科院分区：
文献类型：
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作者：
Kunze, Eric
内波驱动的耗散率和diapycnal扩散系数K推断全球使用细尺度参数化的基础上垂直应变应用到类似的30 000水文铸造。全球耗散为2.06 +/- 0.6 TW，与潮汐和风的内波动力源2.1 +/- 0.7 TW一致。垂直综合耗散率变化的三至四个数量级的升高值在陡峭的地形在西印度群岛和太平洋以及mirachan缓慢扩张的山脊，符合内部潮汐源。但对底强迫的依赖性比线性波浪生成理论弱得多，这表明内波的水平色散和强迫较强时相对较小的局部耗散。分层湍流底边界层厚度变率与潮混合的OGCM参数化不一致。平均扩散系数K =（0.3-0.4）x 10（-4）m（2）s（-1）对深度的依赖性很弱，这表明K = KN 2/gamma的尺度为N-2，因此大部分耗散是在密度跃层中，在2000米深度以下的耗散小于0.08 TW。在2000米的e-折叠尺度下，在底部上方500米处（mab）的底部坐标上的平均扩散系数K接近10（-4）m（2）s（-1）。500 mAb内的平均耗散率为10（-9）Wkg（-1），然后降低至1000 mAb的背景深度值0.15 x 10（-9）Wkg（-1）。没有发现无可争议的支持高耗散率在南极绕极流或参数次谐波不稳定是一个重要的途径，以提高耗散率的半日或昼夜内潮赤道28度和14度纬度，分别，虽然升高的K被发现约30度纬度在北太平洋和南太平洋。
Internal-wave-driven dissipation rates epsilon and diapycnal diffusivities K are inferred globally using a finescale parameterization based on vertical strain applied to similar to 30 000 hydrographic casts. Global dissipations are 2.06 +/- 0.6 TW, consistent with internal wave power sources of 2.1 +/- 0.7 TW from tides and wind. Vertically integrated dissipation rates vary by three to four orders of magnitude with elevated values over abrupt topography in the western Indian and Pacific as well as midocean slow spreading ridges, consistent with internal tide sources. But dependence on bottom forcing is much weaker than linear wave generation theory, pointing to horizontal dispersion by internal waves and relatively little local dissipation when forcing is strong. Stratified turbulent bottom boundary layer thickness variability is not consistent with OGCM parameterizations of tidal mixing. Average diffusivities K = (0.3-0.4) x 10(-4) m(2) s(-1) depend only weakly on depth, indicating that epsilon = KN2/gamma scales as N-2 such that the bulk of the dissipation is in the pycnocline and less than 0.08-TW dissipation below 2000-m depth. Average diffusivities K approach 10(-4) m(2) s(-1) in the bottom 500 meters above bottom (mab) in height above bottom coordinates with a 2000-m e-folding scale. Average dissipation rates are 10(-9) Wkg(-1) within 500 mab then diminish to background deep values of 0.15 x 10(-9) Wkg(-1) by 1000 mab. No incontrovertible support is found for high dissipation rates in Antarctic Circumpolar Currents or parametric subharmonic instability being a significant pathway to elevated dissipation rates for semidiurnal or diurnal internal tides equatorward of 28 degrees and 14 degrees latitudes, respectively, although elevated K is found about 30 degrees latitude in the North and South Pacific.