PhysOcean Lunch Seminar, 18 Oct 2023

Wednesday, October 18, 12:30 PM to 01:30 PM PDT

PHYSICAL OCEANOGRAPHY LUNCH SEMINAR
Modification of Boundary Layer Turbulence by Submesoscale Flows

Leah Johnson
UW Applied Physics Lab

12:30 P.M., 123 Marine Sciences Bldg

ABSTRACT:
The mixing of heat and momentum in the ocean surface boundary layer is dominated by fluid flows on scales rarely resolved by current global and regional ocean circulation models. Instead, these processes are parameterized. Two common parameterizations include vertical mixing by surface forced turbulence (1D) and overturning by submesoscale baroclinic instability. These distinct parameterizations are implemented in tandem yet ignore nonlinear interactions between these two scales that could influence net turbulent fluxes. Using a large eddy simulation of a frontal spin down, this work evaluates how submesoscale flows impact traditional scalings of surface-forced turbulence that are the foundation of OSBL parameterizations. It will be shown that frontal circulations can counteract or suppress the vertical buoyancy flux by surface forced turbulence and suggests vertical mixing (1D) parameterizations over-mix buoyancy in the presence of lateral flows. This over-mixing has a direct influence on the upper ocean potential vorticity budget with implications for properties in the upper ocean that set global circulation.