A Global Ocean Model with Double-Diffusive Mixing

Abstract

A global ocean model is described in which parameterizations of diapycnal mixing by double-diffusive fingering and layering are added to a stability-dependent background turbulent diffusivity. Model runs with and without double-diffusive mixing are compared for annual-mean and seasonally varying surface forcing. Sensitivity to different double-diffusive mixing parameterizations is considered. In all cases, the locales and extent of salt fingering (as diagnosed from buoyancy ratio R?) are grossly comparable to climatology, although fingering in the models tends to be less intense than observed. Double-diffusive mixing leads to relatively minor changes in circulation but exerts significant regional influences on temperature and salinity.