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Frederick T. Mayer and Oliver B. Fringer

1. Introduction In the ocean, because lee waves occur on length scales smaller than the resolution of global circulation models (GCMs), the lee wave drag must be parameterized. Existing parameterizations are based on steady-state solutions for the flow above “linear-height” hills, wherein the height of the hill is much smaller than the wavelength of the wave ( Bell 1975b ; Gill 1982 ). Most common among the unresolved bathymetric features of the deep ocean are the abyssal hills which are

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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

-to-supercritical transition of a hydraulic flow, which implies blockage of certain types of internal waves from propagating upstream. So far, a quantitative evaluation of the flow hydraulics, which is important for understanding the communication of the Indian Ocean with the Pacific Ocean through the Lifamatola Passage, has not been conducted. Fig . 2. Conservative Temperature (Θ) section along the thalweg of the Lifamatola Passage. Flow is to the right, and the locations of numbered CTD stations can be found in Fig. 1b

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Jody M. Klymak, Dhruv Balwada, Alberto Naveira Garabato, and Ryan Abernathey

1. Introduction Stratified flows passing over bathymetry experience drags that are often many orders of magnitude larger than that effected by skin friction alone, due to the creation of internal motions that either radiate away as internal waves ( Bell 1975 ) or are trapped as “nonpropagating” motions near the topography (e.g., Bacmeister and Pierrehumbert 1988 ). These motions are important to large-scale momentum, energy, and mixing in both the ocean and the atmosphere, yet often must be

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

1. Introduction Oceanic processes that have an expression in sea surface height (SSH) occur over a range of time scales. Since the early 1990s satellite altimetry has been used to examine SSH variability related to processes at intraseasonal periods such as mesoscale eddy motions ( Chelton et al. 2011 ) or baroclinic Rossby wave propagations ( Qiu and Chen 2005 ) and at longer periods, including studies of regional and global sea level rise ( Church and White 2011 ). Some higher

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

1. Introduction Flow interactions over space and time with abrupt topography, such as with small-scale islands and deep ocean ridges, can significantly impact regional to large-scale ocean circulation through intense turbulent mixing, formation of mesoscale wakes and eddy shedding behind islands, submesoscale upwelling and downwelling, and generation of lee internal waves ( Baines 1995 ). Along with ocean variability due to topographic features, islands and atolls also modify the atmospheric

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Eric Kunze and Ren-Chieh Lien

. 2016 ; Yang et al. 2018 , 2019 ). Wright et al. obtained the highest of these estimates by correcting for low abyssal currents in HYCOM, but it had ±0.2-TW uncertainties associated with the buoyancy frequency climatology, as well as unquantified uncertainties associated with their bottom velocity product and theoretical assumptions. Lee waves are expected to be a major energy sink for Antarctic Circumpolar Currents in the Southern Ocean (ACC; Gille 1997 ), which accounts for 50% of the global

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

1. Introduction Oceanic internal lee waves and their associated breaking and energy dissipation are thought to play a considerable role in the energy and momentum budgets of the mean and mesoscale ocean circulation. Numerical model studies show that turbulent mixing generated by breaking lee waves, in addition to internal tides and near-inertial waves, are an important driver of the global overturning circulation and may account for up to one-third of the internal wave-driven water mass

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Jody M. Klymak

1. Introduction Slowly varying stratified flow over topography occurs throughout the ocean either due to mean flows or eddies. Energy can be lost from the mean flow by bottom friction (usually small), by the creation of internal waves that radiate and eventually break ( Nikurashin and Ferrari 2010 ), or by other nonlinear processes. By creating internal waves that have to break in the water column, mean flow over rough topography is one of the possible pathways by which the interior of the

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Kristin L. Zeiden, Daniel L. Rudnick, and Jennifer A. MacKinnon

have been shown to generate stationary Rossby waves which are believed to inhibit boundary layer separation ( Boyer and Davies 1982 ). Because these asymmetric effects of background rotation are difficult to observe directly in the real ocean, knowledge of the signed Ro is necessary for making comparisons to these idealized studies. This study quantifies Ro both upstream and downstream of Palau and compares average properties of the currents over instances of eastward and westward flow. Island

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Bowen Zhao, Emma Chieusse-Gérard, and Glenn Flierl

topography gives instability (see the appendix ). This further confirms that our stability result applies to smooth velocity profiles and smooth topography. Note that rotating shallow water models admit unstable modes for monotonic PV profiles owing to the radiation of inertia–gravity waves (i.e., radiative instability; Ford et al. 2000 ; Lahaye and Zeitlin 2016 ), which is however eliminated by our quasigeostrophy approximation. Due to small values of the Rossby number for oceanic eddies, we expect

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