Stratified turbulence dominated by vortical motion and the effects of weak rotation

Strongly stratified flows are composed of vortical motion (i.e. with potential vorticity) and internal gravity waves. At the largest scales of the atmosphere and ocean where Coriolis effects are strong, vortical motion dominates and is described well by quasi-geostrophic turbulence theory. Moving downscale into the atmospheric mesoscale and oceanic submesoscale, rotational effects weaken. In the (inviscid) limit of strong stratification and weak rotation, the vertical scale of vortical motion collapses, and its dynamics reduce to decoupled layers of two-dimensional turbulence. In a real fluid, of course, the vertical scale does not collapse; it is limited by viscosity, small-scale turbulence, or rotation. In this talk, we present simulations of stratified turbulence forced by vortical motion for a wide range of stratifications. We will first discuss turbulence without rotation, and show how energy spectra and vertical length scales depend on stratification. We will then explore the gap between stratified and QG turbulence by examining how the spectra and scales vary as the Rossby number goes from infinity to O(1). Implications for numerical atmosphere/ocean modelling will be discussed.