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Hui Wu

  u − f υ = − g η x , (4) f u + r h   υ = − g η y , (5) ⁡ ( u h ) x + ⁡ ( υ h ) y = 0 . The temporal derivative terms are neglected in (3) – (5) , which means that only the “mean” current with time scale much longer than the frictional spindown time [i.e., O ( h / r )] was considered. Solving (3) and (4) yields (6) u = − g f   ⁡ ( α η x + η y ) , (7) υ = − g f   ⁡ ( − η x + α η y ) , where α ≡ r / fh is the ratio between the friction and Coriolis forcing, termed the linear Ekman number

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Madeleine M. Hamann, Matthew H. Alford, Andrew J. Lucas, Amy F. Waterhouse, and Gunnar Voet

valleys can enhance cross-shore transport driven by alongshore winds ( Zhang and Lentz 2017 , 2018 ). Understanding the dynamics at play within shelf-incising canyon systems both informs our ability to parse out these complicated multidisciplinary puzzles and expands our understanding of canyon physics in general. Comprehensive measurements can be made in these shallower and more easily accessible systems to examine the effects of variable stratification and forcing, and the physical intuition can be

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Magdalena Andres, Ruth C. Musgrave, Daniel L. Rudnick, Kristin L. Zeiden, Thomas Peacock, and Jae-Hun Park

tides observed by the FLEAT PIESs are relatively strong compared to the diurnal signals observed in other PIES experiments; this is consistent with recent high-resolution HYCOM model runs that incorporate tidal forcing (e.g., Arbic et al. 2012 ). The 1/25° HYCOM simulations suggests that Palau in the western tropical North Pacific, sits in a region of particularly strong diurnal internal tides, in addition to strong semidiurnal internal tides there ( Savage et al. 2017 , see their Figs. 14 and 15

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Gunnar Voet, Matthew H. Alford, Jennifer A. MacKinnon, and Jonathan D. Nash

neap tide when peak tidal velocities are only about 0.05 m s −1 , W ≈ 400 m. The tidal excursion parameter (4) ξ = L exc W , the ratio of tidal excursion length scale L exc and topographic length scale W , is thus O ⁡ ( 1 ) . In his seminal work on the generation of tidal internal waves under linear conditions, Bell (1975a) shows that for small tidal excursion parameter ξ , the internal wave response is mainly at the fundamental forcing frequency. For increasing ξ water particles are

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Frederick T. Mayer and Oliver B. Fringer

wave action in vertically sheared flow ( Kunze and Lien 2019 ). In their introduction, Kunze and Lien (2019) offer a handful of additional hypotheses, including measurement and instrument error, under sampling, wave–wave interaction, a narrow radiating bandwidth, and, finally, that lee wave saturation is incompletely parameterized. Saturation theory, as presented above, is based on lee waves of atmospheric scale, where the forcing is hydrostatic. Assuming hydrostatic forcing implies that the wave

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Shuwen Tan, Larry J. Pratt, Dongliang Yuan, Xiang Li, Zheng Wang, Yao Li, Corry Corvianawatie, Dewi Surinati, Asep S. Budiman, and Ahmad Bayhaqi

.1 . 10.1175/2010JPO4451.1 St. Laurent , L. , and R. W. Schmitt , 1999 : The contribution of salt fingers to vertical mixing in the North Atlantic Tracer Release Experiment . J. Phys. Oceanogr. , 29 , 1404 – 1424 , https://doi.org/10.1175/1520-0485(1999)029<1404:TCOSFT>2.0.CO;2 . 10.1175/1520-0485(1999)029<1404:TCOSFT>2.0.CO;2 St. Laurent , L. , J. M. Toole , and R. W. Schmitt , 2001 : Buoyancy forcing by turbulence above rough topography in the abyssal Brazil basin . J. Phys

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Kristin L. Zeiden, Jennifer A. MacKinnon, Matthew H. Alford, Daniel L. Rudnick, Gunnar Voet, and Hemantha Wijesekera

vorticity is strongly correlated with the total velocity ( R = 0.7 in both layers, Figs. 9a,c ). This attached recirculating flow forms eddies if the flow reverses and generates an opposing shear layer inshore of the wake which disrupts the upstream supply of vorticity ( Signell and Geyer 1991 ; Pawlak et al. 2003 ). In our observations, tidal currents are often strong enough to either arrest or reverse the low-frequency flow ( Figs. 3 and 4 ). Thus oscillatory currents force the formation of

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Hemantha W. Wijesekera, Joel C. Wesson, David W. Wang, William J. Teague, and Z. R. Hallock

mixing in the water column depends on the kinetic energy, velocity shear, and strain fields associated with internal tides, near-inertial waves, and low-frequency currents. Therefore we subdivided the moored observations into tidal and subtidal bands to examine the impacts of multiple-scale forcing on mixing around the reef. Figure 7 shows profiles of time-averaged kinetic energy (KE) and squared vertical shear around the reef for tidal and subtidal bands. Two-day high-passed and two-day low

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Jody M. Klymak

investigated. The implications for sampling are briefly discussed ( section 5 ) due to the localized nature of the turbulence generated by the large-scale topography. We also investigate whether the turbulence and drag from the large-scale topography will be represented in regional- and global-scale ocean models. 2. Form drag, dissipation, and our model setup Our model follows Nikurashin et al. (2014) and aphysically applies a body force in the y -momentum equations equal to + fu 0 , where f is the

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Eric Kunze and Ren-Chieh Lien

, and peaks at intermediate wavenumbers | f / U | < | k | < | N / U | in the continuum band ( Fig. 6 ). Divergence of the energy-flux is known as pressure-work and is a forcing term in energy conservation. From the variance-preserving form of (17) with (12) , the peak energy-flux is fNU ⟨ h 2 ⟩ at | kU | = ( fN ) 1/2 for a k −2 topographic height spectrum. For 2D topography, lee-wave radiation (17) is reduced by factor k /( k 2 + ℓ 2 ) 1/2 . The vertical energy-flux can be related to the

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