GFD III , Winter 2025
Professors Jen MacKinnon and Bill Young
T/Th 11-12:20, Nierenberg Hall 101
Course Overview
The goal of GFD 3 --- a third course on geophysical fluid dynamics --- is to provide physical oceanography students with the background required to work at the frontier of research on unbalanced processes with an emphasis on upper-ocean and mixed layer dynamics. Some of these were once balanced but have ceased to be so (e.g. frontal instabilities), some were never balanced (e.g. internal waves), and some are nonlinear interactions between the two. These topics are of increasing community interest and are central to many ongoing SIO research projects but are not accommodated in parts I and II of the geophysical fluid dynamics sequence SIO 212. Most of these topics are not covered in any pedagogical textbooks, and students (and PIs!) are left to pick up what they can from individual research papers. Here we hope to put together a systematic treatment, an broad intellectual framework in which to understand many of these hot topic issues. This material is intended primarily for second year and above students who have at least taken the first year Fluids and GFD courses. Other interested scientists at any level are quite welcome to sit in and join the discussion.
Each class will involve a combination of lectures and discussion of relevant papers that connect lecture material to areas of active research. The paper associated with each lecture is listed below. Additional reference material of possible interest is listed further down.
Schedule
1/7: [Jen] Overview of the class, parameter space, non-dimensional numbers, phenomena
1/9: [Jen] Internal wave dynamics
1/14: [Jen] More internal waves, propagation
1/16: [Jen] Internal waves in variable stratification: vertical modes and WKB
1/21: [Jen] More non-constant media: ray tracing
1/23: [Bill] What is the near-inertial band and why does it deserve three lectures?
1/28: [Bill] (NI continued)
1/30: [Bill] (NI continued)
2/4: [Bill] (NI continued)
2/6: [Bill] (NI continued)
2/11: [Jen] Internal tides and lee waves
2/13 [Jen] Continued lee waves
2/18 [Jen] Ray tracing
2/20: [Bill] Stirring and mixing
2/25: [Bill] Shear Dispersion
2/27: [Bill] Frontogenesis and Frontolysis
3/4: [Bill] Frontogenesis and Frontolysis
3/6: [Bill] Instabilities of the Surface Boundary Layer
3/11: [Jen] Bringing back advective terms to internal waves, part I: wave-wave interactions and the G-M continuum
3/13: [Jen] Bringing back advective terms to internal waves, part II: internal wave / mesoscale nteractions
Office hours: contact either professor individually to figure out a good time to stop by.
HOMEWORK
The classes will involve a combination of formal lectures on the underlying theoretical framework coupled with class discussion and presentation of research papers --- both classic and cutting edge. There will be a few formal homeworks, as we think there are some things you will (later) appreciate having had to derive yourself, and thus understand thoroughly. However befitting a senior graduate student class the majority of the work expected will be a combination of reading assigned cutting edge papers (and coming to class prepared to discuss them), and a modest size term project of flexible nature. There are no written exams.
GRADING
Grades will be based on a combination of written assignments and class participation.
Additional Reference material (click on each one to go to the paper). As a disclaimer, these are not meant be comprehensive or particularly representative, but are some of the papers we will talk about in class. Note that this is still being updated, other suggestions also welcome!
Internal tides: generation and propagation
Internal tide generation in the deep ocean, Garrett and Kunze, 2007
Global observations of Open Ocean Mode-1 M2 internal tides, Zhao et al 16
The role of internal tides in mixing the deep ocean, St. Laurent and Garrett, 2002
Tidal conversion by subcritical topography, Balmforth, Irely and Young, 2002
Conversion of the barotropic tide, Llewellyn Smith and Young, 2002
Climate process team on internal wave–driven ocean mixing, MacKinnon et al, 2017
Abyssal recipes II: Energetics of tidal and wind mixing, Munk and Wunsch 98
Near-inertial internal waves: generation and propagation
Near-inertial internal gravity waves in the ocean, Alford et al, 2015
Propagation of near-inertial oscillations through a geostrophic flow, Young and Ben Jelloul, 97
Simulating the long-range swell of internal waves generated by ocean storms, Simmons and Alford, 2012
Upper-ocean inertial currents forced by a strong storm. Part I: Data and comparisons with linear theory, D’Asaro et al 95
The role of surface waves
Wave‐driven inertial oscillations, Hasselman 70
On the theoretical form of ocean swell. On a rotating earth, Ursell 50
Wave-wave interactions, triad theory, G-M and the internal wave continuum
Deep ocean internal waves: What do we really know?, Wunsch 75
Nonlinear interactions among internal gravity waves, Muller et al 86
Nonlinear energy transfer and the energy balance of the internal wave field in the deep ocean, Olbers 76
A composite spectrum of vertical shear in the upper ocean, Gargett et al 81
A heuristic description of internal wave dynamics, Polzin 04a
Idealized solutions for the energy balance of the finescale internal wave field, Polzin 04b
Advection, phase distortion, and the frequency spectrum of finescale fields in the sea, Pinkel 2008
Toward regional characterizations of the oceanic internal wavefield, Polzin and Lvov 11
Energy transfer from high-shear, low-frequency internal waves to high-frequency waves near Kaena Ridge, HawaiI, Sun and Pinkel 2012
Subharmonic energy transfer from the semidiurnal internal tide to near-diurnal motions over Kaena Ridge, Hawaii, Sun and Pinkel 13
Parametric subharmonic instability of the internal tide at 29 N, MacKinnon et al 13
Subtropical catastrophe: Significant loss of low‐mode tidal energy at 28.9°, MacKinnon and Winters 05
Jody Klymak’s matlab representation of the G-M spectrum is here
Finescale parameterizations of mixing as applied to data:
Finescale parameterizations of turbulent dissipation, Polzin et al 95
Global abyssal mixing inferred from lowered ADCP shear and CTD strain profiles, Kunze et al 06
Spatial and temporal variability of global ocean mixing inferred from Argo profiles, Whalen et al 12
Suppression of internal wave breaking in the Antarctic Circumpolar Current near topography, Waterman et al 14
Finescale parameterizations of turbulent dissipation, Polzin et al 14 (I’m noting a theme in his titles)
Global patterns of diapycnal mixing from measurements of the turbulent dissipation rate, Waterhouse et al 14
Estimating the mean diapycnal mixing using a finescale strain parameterization, Whalen et al 15
Parameterizations for models
Abyssal recipes, Walter Munk, 66
Parameterizing tidal dissipation over rough topography, Jayne et al 01
Estimating tidally driven mixing in the deep ocean, St. Laurent et al 02
An abyssal recipe, Polzin 09
Sensitivity of the ocean state to the vertical distribution of internal-tide-driven mixing, Melet et al 13
Frontogenesis
Atmospheric frontogenesis models: Mathematical formulation and solution, Hoskins and Bretherton ‘72
Frontogenesis by horizontal wind deformation fields, Stone 66
Quasi-geostrophic frontogenesis, Williams and Plotkin 68
A new look at the ω‐equation, Hoskins et al 78
Mixed layer restratification due to a horizontal density gradient, Tandon and Garrett ‘94
Geostrophic adjustment: A mechanism for frontogenesis, Ou 84
Frontogenesis in a fluid with horizontal density gradients, Simpson and Linden 89
Internal wave mesoscale interaction
Global energy conversion rate from geostrophic flows into internal lee waves in the deep ocean, Nikurashin and Ferrari 11
Radiation and dissipation of internal waves generated by geostrophic motions impinging on small-scale topography: Theory, Nikurasin and ferrari 10
Mesoscale eddy–internal wave coupling. Part II: Energetics and results from PolyMode, Polzin 10
Wave capture and wave–vortex duality, buhler and mcintyre 05
Near-inertial waves in strongly baroclinic currents, Whitt and Thomas 13
Resonant generation and energetics of wind-forced near-inertial motions in a geostrophic flow, whitt and thomas 15
On the modifications of near-inertial waves at fronts: implications for energy transfer across scales, Thomas 17
Large-scale impacts of the mesoscale environment on mixing from wind-driven internal waves, Whalen et al 18