GFD III , Winter 2019
Professors Jen MacKinnon and Bill Young
T/Th 9:30-10:50, Nierenberg Hall 101
The goal of SIO212C --- 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 student led 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.
1/8: NO CLASS
1/10: Overview of submesoscale processes and dynamics, governing equations, parameter space for the quarter, plan for the class
1/15: Review of basic internal wave equations, dynamics [Paper of the day: tbd…]
1/17: More internal wave basics, propagation, WKB, ray tracing.
1/22: Internal tides: generation, modes, global patterns, power.
1/24, ** 2:30-4pm: Near-inertial waves. Slab model wind generation. Interaction with ambient vorticity field. Global maps, power.
1/29: Wave / mean flow interaction
1/31: The kinematics of passive scalars and passive vectors. Stirring, mixing, gradient amplification and enhanced dispersion.
2/5: The internal wave continuum. Garrett-Munk. Triad interactions and energy transfer. Mechanics and patterns of wave breaking. Global patterns and budgets.
2/7: Continuum discussion continued. Some GM+wave-wave interaction +finescale parameterization slides
2/12: Continuum part 3, and a few lee waves.
2/19: Quasigeostrophic frontogenesis. Semigeostrophic frontogenesis: balanced frontogenesis --- the Hoskins \& Bretherton model and unbalanced frontogenesis --- Blumen's model.
2/21: Frontogenesis and instabilities continued
2/26: Frontogenesis and instabilities continued
2/28: Frontogenesis and instabilities continued
3/5: Frontogenesis and instabilities continued
3/7: Back to wave / mean flow interactions, the complicated version, part I
3/12: Back to wave / mean flow interactions, the complicated version, part II
3/14: Student presentations
Office hours: contact either professor individually to figure out a good time to stop by.
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.
Homework #1 (click on it), due Thursday Jan 17th in class.
Homework #2, due 14 Feb in class
Homework #3, due tbd
Homework #n, student presentations and short write up.
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 talked about in class.
Internal tides: generation and propagation
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
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
The role of surface waves
Wave‐driven inertial oscillations, Hasselman 70
Wave-wave interactions, triad theory, G-M and the internal wave continuum
Nonlinear interactions among internal gravity waves, Muller et al 86
A composite spectrum of vertical shear in the upper ocean, Gargett et al 81
Toward regional characterizations of the oceanic internal wavefield, Polzin and Lvov 11
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
Finescale parameterizations of mixing as applied to data:
Finescale parameterizations of turbulent dissipation, Polzin et al 95
Finescale parameterizations of turbulent dissipation, Polzin et al 14 (I’m noting a theme in his titles)
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
Atmospheric frontogenesis models: Mathematical formulation and solution, Hoskins and Bretherton ‘72
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
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
Wave capture and wave–vortex duality, buhler and mcintyre 05
Near-inertial waves in strongly baroclinic currents, Whitt and Thomas 13