An Enhanced Langmuir Turbulence Parameterization With Nonlocal Momentum and Scalar Fluxes

Abstract

Langmuir turbulence plays a critical role in the oceanic surface boundary layer by efficiently transporting momentum, heat, gases, and nutrients. Since its characteristic scale (meters to tens of meters) is far smaller than typical grid cells of ocean general circulation models, it must be parameterized. A key limitation of existing Langmuir schemes is the omission of Langmuir-induced nonlocal fluxes. While these schemes reproduce scalar fields reasonably well, the lack of nonlocal momentum flux results in velocity simulations with excessive vertical shear and unrealistic near-surface values. To overcome this limitation, we introduce an enhanced Langmuir turbulence parameterization that incorporates a unified formulation for both Langmuir and convective nonlocal fluxes of momentum and scalars into the K-profile parameterization framework. When evaluated against large-eddy simulation benchmarks, the new scheme demonstrates significant improvement in velocity simulations while maintaining excellent accuracy for scalar fields. These results underscore the necessity of including nonlocal fluxes for accurate modeling of Langmuir turbulence effects.