Eddies and vortices in ocean basin dynamics

A wind-driven, closed-basin quasi-geostrophic ocean model is computed at ve ry high horizontal resolution to study the effect of increasing Reynolds nu mber (Re) on eddy variability. Five numerical simulations are performed wit h identical configurations, varying only in horizontal resolution and visco sity coefficient (and therefore Re). Qualitative changes in the structure o f eddy variability are evident in the dramatic increase of isolated vortex structures at the highest Re. While the time-mean kinetic energy is relativ ely independent of Re, the vortex emergence contributes to a continual incr ease with Re of eddy kinetic energy and meridional vorticity flux. The rate of increase slows somewhat at the highest Re, indicating the possibility o f a regime where eddy variability becomes insensitive to further increases in Re.