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PhD Dissertation Defense-Dual Degree University of Sao Paulo and SMAST at UMass Dartmouth-Caue Lazaneo

When: Thursday, July 29, 2021
9:00 AM - 10:00 AM
Where: > See description for location
Description: The Oceanographic Institute of the University of Sao Paulo, Brazil
and
The School for Marine Science and Technology at the University of Massachusetts, Dartmouth, USA
PhD Dissertation Defense Announcement

"Mixing and Submesoscale Dynamics on the Western South Atlantic Ocean"

By
Caue Zirnberger Lazaneo

Advisors:
Prof. Ilson Carlos Almeida da Silveira (USP Advisor)
Prof. Amit Tandon (UMass Dartmouth Advisor)

Committee:
Prof. Joseph Harari (USP)
Prof. Daniel MacDonald (UMass Dartmouth)
Prof. Paulo Calil (Helmholtz-Zentrum Hereon)

Thursday, July 29, 2021
9:00 am (Eastern Standard Time)
Via Zoom

Abstract: This dissertation addresses two oceanic processes that result in the dissipation of turbulent kinetic energy in the western South Atlantic Ocean. In the first study, we investigate the role of the vertical shear generated by the flow reversal between the poleward-flowing Brazil Current and the equatorward-flowing Intermediate Western Boundary Current. From unprecedented measurements of microstructure in the region, we observe that the vertical shear at the interface between the two currents locally destabilizes the water column, and may overcome the stabilizing effect of stratification. Thus, mixing processes occur, resulting in property vertical exchanges at the base of the mixed layer. In the second study, we seek intrapycnoclinic, submesoscale coherent vortices (SCVs) in the VTR region from synoptic observations. We captured two anticyclonic SCVs embedded in a meander of the South Equatorial Current (SEC) from high-resolution measurements of temperature, salinity, and velocity. The SCVs were found in the lee of the Columbia Seamount. Through microstructure measurements taken in one of the SCVs, we observe turbulent kinetic energy dissipation rates similar in magnitude to those measured in the mixed layer. In the third study, we investigate whether the VTR is prone to generate submesoscale vortices. We then simulate, with a regional ocean numerical model, the SEC interacting with the ridge. We observe that this type of vortex is often formed in the region at different topographic features and different depths along its 900km extension. From the interaction between the SEC and the topographic features of the VTR, vortical filaments of Rossby number O(1) form downstream of the topography, creating potential vorticity anomalies. These filaments eventually evolve, roll up and form SCVs. We suggest that VTR can be considered a hotspot for the generation of submesoscale vortices.
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Join Zoom Meeting
https://umassd.zoom.us/j/92894955096?pwd=T1FXaGovSU5qazVqRHR4S0VsWmt5dz09
Meeting ID: 928 9495 5096
Passcode: 991062
For additional information, please contact Sue Silva at s1silva@umassd.edu
Contact: > See Description for contact information
Topical Areas: School for Marine Sciences and Technology, SMAST Seminar Series