Seminar: Dr. Laur Ferris – UNC CH

UNC-CH’s Department of Earth, Marine, and Environmental Sciences is proud to host a guest seminar by Laur Ferris. This event is scheduled for Friday, November 12th, at 12:30 pm. This seminar is both in-person, in room G202 on the ground floor of Venable/Murray Hall on UNC campus in Chapel Hill NC and will be broadcasted live online via Zoom (Meeting ID: 994 3817 3742).

Presenter Affiliation: Virginia Institute of Marine Sciences; Physical Sciences & Physical Oceanography

Title: Surface boundary layer and interior turbulence in intense frontal zones: lessons learned from an 82-day glider mission in the Antarctic Circumpolar Current

Abstract: Numerous physical processes are responsible for forward energy cascade and turbulence at oceanic fronts, but their relative impact is not clear. My work investigates wind-sheared turbulence in the ocean surface boundary layer (OSBL) and internal wave interactions in the ocean interior with focus the parameterizations used to quantify these processes. At the OSBL, meteorological forcing mixes and restructures the upper ocean. This mixing is represented by boundary layer scalings (BLS) of shear and convective turbulence in numerical models. We used 6 weeks of glider microstructure from AUSSOM (Autonomous Sampling of Southern Ocean Mixing) to test the validity of this approach in the upper Southern Ocean. In the interior, finescale strain parameterization (FSP) for turbulent dissipation rate is popular for quantifying mixing where only CTD data is available. However, it is not as applicable to intense frontal regions where temperature-salinity fronts create double diffusive instability. Direct turbulence measurements from DIMES (Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) and AUSSOM are used to show FSP can have biases of up to 8 orders of magnitude when frontal physics contaminate the CTD strain spectrum. We propose that the FSP methodology be modified in two simple ways for use in frontal zones. The result of this work will help to constrain global values for diffusivity used for the calibration of next-generation circulation models.