S. Legg et J. Marshall, A HETON MODEL OF THE SPREADING PHASE OF OPEN-OCEAN DEEP CONVECTION, Journal of physical oceanography, 23(6), 1993, pp. 1040-1056
A point-vortex heton model of the lateral dispersion of cold water for
med in open-ocean deep convection is developed and studied as an ideal
ized representation of the sinking and spreading phase of open-ocean d
eep convection. The overturning and geostrophic adjustment of dense fl
uid on and below the radius of deformation scale, formed by cooling on
the large-scale, are parameterized in the model by introducing paired
, discrete point vortices (hetons) of cyclonic sense in the surface la
yer, anticyclonic below, driving a cold baroclinic vortex. The convect
ion site is imagined to be made up of many such baroclinic vortices, e
ach with a vertically homogeneous core carrying cold, convectively tai
nted waters. The point vortices are introduced at a rate that depends
on the large-scale cooling and the intensity assumed for each vortex.
The interaction of many cold baroclinic vortices, making up a cloud, i
s studied using point-vortex Green's function techniques. The current
solenoids of the individual elements sum together to drive a large-sca
le rim current around the convection site, cyclonic above, anticycloni
c below, which is associated with a baroclinic zone on a scale of the
order of the ambient radius of deformation. For parameters typical of
open-ocean deep convection, the cloud of point vortices breaks down ba
roclinically on a time scale of a few days, into Rossby radius-scale '
'clumps.'' These extended hetons efficiently flux the cold water away
laterally from the convection site and affect an inward transfer of he
at sufficient to offset loss to the atmosphere.