Stratified turbulence in the atmosphere and the oceans

Abstract

Some recent progress in the field of stratified turbulence is reported. The progress has been made by combining recent theoretical development with simulations and data analysis. On the basis of scaling arguments, numerical simulations and observational analysis it is argued that the dynamics of the mesoscale range, that is wave lengths from one to five hundred kilometres, in the upper troposphere and lower stratosphere is controlled by a special type of forward energy cascade which is typical for strongly stratified turbulence. In contrast to the classical Kolmogorov cascade, the stratified turbulence cascade is characterised by two radically different length scales in the horizontal and the vertical and is a cascade of both kinetic and potential energy. Kinetic energy is observed to be approximately equipartitioned between vortical and divergent modes. It is also suggested that this type of dynamics can be found in the interior of the ocean at horizontal scales between 10 metres and 10 kilometres. A number of observational studies previously reported in the literature will be referenced in support to this.