The role of shear instability in thermohaline intrusions

Thermohaline interleaving is important in most of the world's ocean as a mechanism for laterally fluxing salt, heat, and nutrients between water masses. Interleaving is driven by the release of potential energy caused by buoyancy changes due to differential diffusion of heat and salt. The flows are composed of stacked intrusions that flux more buoyant and less buoyant water in opposite directions. We investigate the role of shear instability (caused by this juxtaposed motion) on intrusion growth. A nonlinear, one-dimensional model (Walsh and Ruddick, 1998) is upgraded to include a shear induced turbulent mixing parameterization based on Direct Numerical Simulation results. The consequence of these revisions is demonstrated by density profiles that more closely simulate observational data. We will describe both revised model and the corresponding effects on the lateral fluxes.

Walsh, D. & B. Ruddick, 1998: “Nonlinear equilibration of thermohaline intrusions”, J. Phys. Oceanogr. 28, 1043-1069.