Gravity wave–fine structure interactions: A reservoir of small-scaleand large-scale turbulence energy

摘要

A direct numerical simulation of gravity wave — finestructure interactions is performed to evaluate the effects ofsuch a superposition on instability and turbulence for finestructure shears and a gravity wave (GW) amplitude that areindividually stable. The superposition leads to deformationsof the fine structure and GW fields that exhibit Kelvin-Helmholtz (KH) shear instabilities and turbulence extendingover more than 20 buoyancy periods. KH instabilitiesoccur on multiple scales, deplete the kinetic energy of theinitial fine structure, and yield a layering of the potentialtemperature field resembling "sheet and layer" structuresobserved in the oceans and the atmosphere. The interactionshave a much smaller effect on the GW amplitude. Suchinteractions among GWs and fine structure are likelyubiquitous throughout the atmosphere and oceans and mayaccount for sporadic bursts of turbulence and its persistencein regions of apparent static and dynamic stability (Ri > 1/4).Citation: Fritts, D. C., L. Wang, and J. Weme (2009), Gravitywave—fine structure interactions: A reservoir of small-scale andlarge-scale turbulence energy.