University of Washington

Physical Oceanography Lunchtime Seminar, Winter 2013

12:30 Wednesdays, OSB 425.

Seminar organizer: Matthew Alford, malford (at) uw.edu, 221-3257.

To add your name to the announcement list, please visit https://mailman1.u.washington.edu/mailman/listinfo/phys_ocean_seminars.

Date	Speaker	Institution	Title	Abstract
Jan 9	Gunnar Voet	APL/UW	Flow, mixing and hydraulics in the Samoan Passage
Jan 16	Cimarron Wortham	MIT	Space-time scales of low-frequency ocean variability
Jan 23	NO SEMINAR
Jan 30	Jacob Wenegrat	UW	Masters defense: Near-surface Shear Flow on the Equator
Feb 6	Hayler Dosser	UW	Properties of Near-Inertial Waves in the Arctic Ocean from Year-Round Observations
Feb 13	Torge Martin	APL/UW	Southern Ocean forced multi-centennial climate variability and global impacts	Self-sustained oscillations of open ocean deep convection in the Southern Ocean drive a multi–centennial mode of climate variability in the Kiel Climate Model (KCM). The simulated deep convection in the Atlantic Sector of the Southern Ocean has intriguing similarities with the Weddell Polynya observed in the 1970s. The model shows how the competing roles of mid to deep ocean warming and surface freshening in forcing local buoyancy changes can cause global climate variations on a centennial timescale. These can be seen in global surface air temperature, Southern Hemisphere sea ice coverage, Southern Ocean and North Atlantic sea surface height, the Antarctic Circumpolar Current and the Atlantic Meridional Overturning Circulation (AMOC). Because of their magnitude the associated climate variations have the potential to locally mask global warming signals. In this presentation I will explain the mechanism behind the convection flip-flop and how it impacts the AMOC.
Feb 20	Jonathan Nash	OSU	The Unpredictable Nature of Internal Tides in the Coastal Ocean
Feb 27	Beth Scott	U. of Aberdeen	Marine renewable energy extraction, climate change and trophic linkages: What do we need to understand?
Mar 6	Kathleen Dohan	ESR	20 year trends in OSCAR surface currents
Mar 13	Jody Klymak	U. Victoria	Observational Examples of Submesoscale Lateral Mixing
TUES Mar 19 3:30 [SPECIALDATE/TIME]	Matthew Hecht	Los Alamos National Laboratories	Response of Atlantic Circulation to Freshwater Perturbations in a Strongly Eddying Ocean Model
Mar 20	Brian White	UNC Chapel Hill	Mass and energy exchange at coastal density fronts: mixing layers, gravity currents, and internal waves	In stratified coastal waters, large horizontal density gradients are common. These horizontal gradients result in propagating density fronts, which produce vertical shear, turbulent mixing, and can even generate large amplitude internal waves. In this talk two specific examples of flows with horizontal density gradients are discussed. The first is a buoyant plume propagating into stratification, which under certain conditions undergoes a resonant interaction with internal waves at the plume front. This resonance can produce large waves that develop overturning circulation and contain mixed fluid. The second case involves the mixing of two water masses with large horizontal shear and horizontal density gradient. An example is tidal flow which separates at the boundary of an island wake. In this case, vertical vorticity due to the horizontal shear tilts under gravity, is stretched and intensified, and produces large vertical mixing. These examples are explored through a combination of Boussinesq Navier-Stokes simulations, laboratory experiments, and theory, with a focus on scaling, evolution of energy budgets, turbulent mixing, and hydraulic theory for stratified fluids.