Parameterization of Langmuir Turbulence in Second Moment Closure Models and the Prediction of Near-surface Dispersion for Buoyant Tracers.

Recently developed second moment closure models of Langmuir turbulence in the ocean are improved through the application of more accurate realizability constraints. These constraints avert negative values for the production of turbulent kinetic energy in the closure model when Eulerian and Stokes shears are not aligned. The role of boundary layer turbulence in determining the vertical mixing of near-surface buoyant particles and tracers, and their horizontal dispersion, are examined using simulated buoyant trajectories from turbulence-resolving Large Eddy Simulations, where surface wave forcing of Langmuir turbulence is included through the Craik-Leibovich vortex force. The second moment closure of Langmuir turbulence may be used to account for these effects on upper ocean turbulence on particle and tracer dispersion within ocean models that parameterize upper-ocean mixing.