NSFGEO-NERC: Energy transfer between submesoscale vortices and resonantly-forced inertial motions in the northern Gulf of Mexico

点击翻译按钮获取中文摘要

Submesoscale flows and near-inertial motions are ubiquitous features of the upper ocean. Recently developed theories have posited that the interaction of submesoscale flows and near-inertial motions could play an important role in closing the energy budgets of both the balanced circulation and the unbalanced waves. These theories have yet to be fully tested in the field due to the challenges of observing both types of motions in a relatively controlled setting. The northern Gulf of Mexico is a natural laboratory that is ideal for doing this. Here, the Mississippi-Atchafalaya river plume forms a rich field of submesoscale eddies and fronts, which in the summer are driven by a land-sea breeze that forces inertial motions at near resonance.The proposed research will involve intensive field campaigns utilizing novel observational techniques that will be closely integrated with idealized and realistic numerical simulations to study the interaction of submesoscale eddies and near-inertial motions in the Mississippi-Atchafalaya river plume. The objective will be to characterize, quantify, and understand the energy exchanges between balanced and unbalanced motions and the turbulent cascade that can result from the interaction. More specifically, the numerical and observational experiments will be designed to test the hypotheses that periodic straining of isopycnals by inertial motions in fronts, subduction of low potential vorticity water, and the propagation, trapping, and reflection of near-inertial waves interacting with submesoscale eddies facilitate the energy exchange and result in enhanced mixing throughout the water column.The proposed research tackles one of the outstanding questions in physical oceanography of how the kinetic energy in the balanced circulation is dissipated, in particular through wave-mean flow interactions. This question has been studied mostly theoretically for idealized flow configurations, but it has not been explored observationally in a controlled setting, as proposed here. The research will integrate observations with submesoscale-resolving simulations and large-eddy simulations, a combination that has proven to be effective in understanding the fundamental physics of complex, multi- scale observed flows.