Physical Oceanography Seminars usually take place at 10:30 am on Fridays in the Corless auditorium.
Seminar coordinators are Melanie Feen and Catrina Nowakowski.
|Seminars at other institutions|
January 26 Yana Bebieva Yale
Title: Double-diffusive mixing in the Arctic Ocean
Abstract: State-of-the-art coupled climate models show major disagreements with observations across a wide range of parameters of the Arctic system. Unresolved processes that require parameterization in numerical models might be the major cause of such discrepancies. In this talk, I will discuss a class of small-scale (sub-grid scale) convective mixing processes (double-diffusive processes) that are prevalent throughout the Arctic Ocean and are one of the main mechanisms by which deep ocean heat is fluxed upward to the surface ocean. Using ocean observations from the extensive Ice-Tethered Profiler dataset, temperature and salinity measurements of an Atlantic Water mesoscale eddy are analyzed to understand the effects of velocity shear on a range of double-diffusive processes. Estimated lateral variations in vertical fluxes across the eddy allow for speculation that double diffusion speeds up the eddy decay, having important implications for the transfer of Atlantic Water heat in the Arctic Ocean. Motivated by observations that show the coexistence of thermohaline intrusions and double-diffusive staircases, the origin of double-diffusive staircases in the Arctic Ocean is investigated for the particular background setting in which both temperature and salinity increase with depth.
February 2 Georgi Sutyrin, Emeritus Marine Research Scientist, URI
Title: Maintenance of long-lived eddies in the ocean
Abstract: At present there is no unified conceptual framework in the understanding and the description of how coherent vortices survive in turbulent environment. E.g., super long-lived oceanic vortices are able to be traced for years while maintaining quick fluid rotation. We analyze several physical mechanisms producing vortex self-intensification: kinetic energy exchange in barotropic vortex interactions, potential energy release due to baroclinic instability, double-diffusive secondary circulation as well as the centrifugal instability.
February 9 Mathieu Dever, Postdoctoral Investigator, WHOI
Title: Size differentiated export of particulate organic matter by meso- and submeso-scale dynamics
Abstract: The export of particulate organic matter (POM) is affected by near-surface velocities related to the dynamics of meso- and submeso-scale processes. In the horizontal, POM can aggregate in regions of strong vorticity and strain rate, and in the vertical, subsmesoscale dynamics associated with vertical velocities as large as O(100 m/day) can subduct POM below the mixed layer. Combining these advective motions with the size-dependent sinking of POM results in a sorting mechanism that separates fast- and slow-sinking particles, where slow-sinking particles are more likely to be advected away from their production site before sinking below the mixed layer. This separation leads to patchy export and observational challenges to quantify export fluxes.
In the present study, we use the submesoscale-resolving Process Study Ocean Model (PSOM) coupled with a particle-tracking model to simulate the eddy dynamics in a region of the North Pacific, which we validate with glider observations. We quantify the role of eddy dynamics on POM export and the particle sorting resulting from the POM size spectrum and its spatial patchiness. Synthetic autonomous platforms consisting of moored or drifting sediment traps and gliders are used as part of an Observing System Simulation Experiment (OSSE) to assess the effectiveness of different sampling strategies in capturing the statistics of the export fluxes.
March 9 Anthony Kirincich WHOI
March 23 Renske Gelderloos Johns Hopkins
April 6 Kerry Emanuel MIT
April 20 R. Dwi Susanto U. Maryland