Nonpropagating Form Drag and Turbulence due to Stratified Flow over Large-Scale Abyssal Hill Topography
Nonpropagating Form Drag and Turbulence due to Stratified Flow over Large-Scale Abyssal Hill Topography
复制标题
大型深渊山地貌上层流引起的非传播形式阻力和湍流
DOI：
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发表时间：
2018
影响因子：
3.5
通讯作者：
J. Klymak
中科院分区：
文献类型：
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作者：
J. Klymak
采用线性理论和波-波相互作用引起的能量级联率，对“深海丘陵”上空定常分层流中的阻力和湍流进行了参数化。线性理论没有阻力或能量损失，由于大规模测深，因为波的固有频率小于科里奥利频率是渐逝的。数值计算工作通过高过地形和估计辐射和湍流来检验理论。增加较大尺度的水深测量，将产生渐逝内波，产生非线性和湍流，驱动耗散约两倍的辐射波的地形频谱选择。这个阻力在强迫速度中是线性的，与具有二次阻力的大气参数化相反。包含小尺度和大尺度水深测量的模拟比仅将大尺度和小尺度耗散加在一起具有更多耗散，因此尺度耦合。大尺度湍流是局部的，一般在大型障碍物的背风面。中等规模的区域模式部分解决了“非传播”波数，导致他们是否需要大规模的能量损失参数化的问题。不同的分辨率的模拟表明，如果gridcell的高度与宽度的比率小于均方根地形坡度，那么耗散高估了粗糙的模型（高达25%）;相反，它可以被低估了高达2倍，如果该比率更大。大多数区域模拟可能处于第二种状态，应增加额外阻力以代表大尺度测深，不足之处至少与深海丘陵参数化的不足之处一样大。
Drag and turbulence in steady stratified flows over “abyssal hills” have been parameterized using linear theory and rates of energy cascade due to wave–wave interactions. Linear theory has no drag or energy loss due to large-scale bathymetry because waves with intrinsic frequency less than the Coriolis frequency are evanescent. Numerical work has tested the theory by high passing the topography and estimating the radiation and turbulence. Adding larger-scale bathymetry that would generate evanescent internal waves generates nonlinear and turbulent flow, driving a dissipation approximately twice that of the radiating waves for the topographic spectrum chosen. This drag is linear in the forcing velocity, in contrast to atmospheric parameterizations that have quadratic drag. Simulations containing both small- and large-scale bathymetry have more dissipation than just adding the large- and small-scale dissipations together, so the scales couple. The large-scale turbulence is localized, generally in the lee of large obstacles. Medium-scale regional models partially resolve the “nonpropagating” wavenumbers, leading to the question of whether they need the large-scale energy loss to be parameterized. Varying the resolution of the simulations indicates that if the ratio of gridcell height to width is less than the root-mean-square topographic slope, then the dissipation is overestimated in coarse models (by up to 25%); conversely, it can be underestimated by up to a factor of 2 if the ratio is greater. Most regional simulations are likely in the second regime and should have extra drag added to represent the large-scale bathymetry, and the deficit is at least as large as that parameterized for abyssal hills.
影响因子：
3.5
作者：
de Lavergne, Casimir;Madec, Gurvan;Garabato, Alberto C. Naveira
通讯作者：
Garabato, Alberto C. Naveira
影响因子：
3.5
作者：
Naveira Garabato A
通讯作者：
Naveira Garabato A
影响因子：
3.5
作者：
Brearley, J. Alexander;Sheen, Katy L.;Waterman, Stephanie
通讯作者：
Waterman, Stephanie