EDDY KINETIC-ENERGY AND MOMENTUM FLUX IN THE SOUTHERN-OCEAN - COMPARISON OF A GLOBAL EDDY-RESOLVING MODEL WITH ALTIMETER, DRIFTER, AND CURRENT-METER DATA
Jl. Wilkin et Ra. Morrow, EDDY KINETIC-ENERGY AND MOMENTUM FLUX IN THE SOUTHERN-OCEAN - COMPARISON OF A GLOBAL EDDY-RESOLVING MODEL WITH ALTIMETER, DRIFTER, AND CURRENT-METER DATA, J GEO RES-O, 99(C4), 1994, pp. 7903-7916
The ability of a seasonally forced high-resolution global ocean genera
l circulation model to simulate eddy variability and associated energy
and momentum transfer processes in the Southern Ocean is assessed by
comparing model statistics with observations. The observations include
Geosat altimeter data analyzed for surface velocity variance at satel
lite ground track crossover points, current-meter data from the Agulha
s and Campbell plateaus, and surface drifter data in the Tasman Sea. I
n western boundary currents and energetic regions of the Antarctic Cir
cumpolar Current model eddy kinetic energy is lower than observed by t
ypically a factor of 4, and in less energetic regions by a factor of 1
0. Differences in the location and extent of energetic regions are rel
ated to smoothness of the model bathymetry and other features of the m
odel configuration. Eddy momentum flux divergence and eddy to mean kin
etic energy conversion at the surface are diagnosed from the model. Th
ese show regions where eddy activity accelerates the mean flow through
instability processes. Observational estimates of these terms are com
puted using mean flow gradients from hydrography climatology and altim
eter eddy statistics. Several features of the spatial distribution of
the observational estimates are consistent with the model and suggest
that future calculations of mean currents from altimeter data will all
ow direct computation of eddy to mean current momentum and energy conv
ersion terms.