3-DIMENSIONAL QUASI-GEOSTROPHIC CONTOUR DYNAMICS, WITH AN APPLICATION TO STRATOSPHERIC VORTEX DYNAMICS Academic Article uri icon

abstract

  • A new, versatile, and efficient numerical algorithm for threedimensional quasigeostrophic calculations using contour dynamics/surgery is described and illustrated. The numerical algorithm models the fluid as dissipationless (in contrast with conventional numerical models having artificial subgrid diffusivities) and is based on the Lagrangian representation in fluid dynamics, allowing one to focus resolution on the most dynamically active parts of the flow, i.e. regions of high potentialvorticity gradients. The algorithm is generally applicable to a wide range of idealized atmospheric and oceanic flows. Important effects of compressibility, variable stratification, surface temperature gradients and topography are included. It is applied in this paper to study how a threedimensional barotropic vortex responds to topographic forcing at the bottom boundary or tropopause. Two regimes of wave breaking are found: the first is local wave breaking, which occurs near the lower boundary for strong topographic forcing; the second is remote wave breaking, which occurs at the upper levels for weak topographic forcing. The local wave breaking corresponds closely to the wave breaking seen in singlelayer calculations, if the layer depth is chosen equal to a density scaleheight. Rather than having an aspect ratio equal to Prandtl's ratio (as one might expect from geostrophic turbulence), features resulting from wave breaking in a compressible atmosphere with weak vertical shear tend to have a nearly barotropic structure. Copyright 1994 Royal Meteorological Society

published proceedings

  • QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY

author list (cited authors)

  • DRITSCHEL, D. G., & SARAVANAN, R.

complete list of authors

  • DRITSCHEL, DG||SARAVANAN, R

publication date

  • January 1, 1994 11:11 AM

publisher