Statistically stationary differential diffusion in a large-scale internal waves–vortical modes environment

Theory is developed for differential diffusion (different turbulent transports of heat and salt when both are stably stratifying) within a statistically stationary large-scale internal wave environment. This complements recent laboratory and numerical studies where turbulence is generated impulsively. An account is given over six decades in vertical wavenumber. Persistent upgradient (countergradient) fluxes characterize the fine scales. Because higher thermal conductivity suppresses fine scale upgradient heat transport, net downgradient transports favor heat over salt.