Sy. Legg et al., A HETON PERSPECTIVE OF BAROCLINIC EDDY TRANSFER IN LOCALIZED OPEN-OCEAN CONVECTION, Journal of physical oceanography, 26(10), 1996, pp. 2251-2266
A simple point-vortex ''heton'' model is used to study localized ocean
convection. In particular, the statistically steady state that is est
ablished when lateral buoyancy transfer, effected by baroclinic instab
ility, offsets the localized surface buoyancy loss is investigated. Pr
operties of the steady state, such as the statistically steady density
anomaly of the convection region, are predicted using the hypothesis
of a balance between baroclinic eddy transfer and the localized surfac
e buoyancy loss. These predictions compare favorably with the values o
btained through numerical integration of the heton model. The steady s
tate of the heton model can be related to that in other convection sce
narios considered in several recent studies by means of a generalized
description of the localized convection. This leads to predictions of
the equilibrium density anomalies in these scenarios, which concur wit
h those obtained by other authors. Advantages of the heton model inclu
de its inviscid nature, emphasizing the independence of the fluxes aff
ected by the baroclinic eddies from molecular processes, and its extre
me economy, allowing a very large parameter space to be covered. This
economy allows us to examine more complicated forcing scenarios: for e
xample, forcing regions of varying shape. By increasing the ellipticit
y of the forcing region, the instability is modified by the shape and,
as a result, no increase in lateral fluxes occurs despite the increas
ed perimeter length. The parameterization of convective mixing by a re
distribution of potential vorticity, implicit in the heton model. is c
orroborated: the heton model equilibrium state has analogous quantitat
ive scaling behavior to that in models or laboratory experiments that
resolve the vertical motions. The simplified dynamics of the heton mod
el therefore allows the adiabatic advection resulting from baroclinic
instability to be examined in isolation from vertical mixing and diffu
sive processes. These results demonstrate the importance of baroclinic
instability in controlling the properties of a water mass generated b
y localized ocean convection. A complete parameterization of this proc
ess must therefore account for the fluxes induced by horizontal variat
ions in surface buoyancy loss and affected by baroclinic instability.