Instabilities in the Stratified, Wave Forced Ocean Mixed Layer

Instabilities in a stratified ocean mixed layer model with surface gravity wave forcing are examined to study the interactions between the Langmuir turbulence scale and the submesoscale. Linear instabilities at these two scales have been studied independently, however, this work serves to bridge the gap between these classes of instability. Wave and wind effects are added to a linearized, stratified upper ocean model through the addition of Stokes-drift (a net current in the direction of wave propagation) and viscosity with surface wind forcing. In the limit of no wave or wind forcing and strong stratification, this system is dominated by symmetric, geostrophic, or Kelvin-Helmholtz instability. In the limit of no stratification and strong wave forcing, the system is dominated by wave induced shear instability. The system is studied on a continuum between these two extremes to understand if the separate classes of instability still appear independent in the presence of both strong wave forcing and strong stratification, or if they interact to produce hybrid modes.