Posted by Bo Qiu on November 13, 2000 at 17:49:59:
In Reply to: Cf: Heat budget in KOE of Latif-Barnett mode posted by Art Miller on November 09, 2000 at 14:47:16:
I just have a quick comment on the heat budget calculation
in the SST tendency equation. From most of OGCMs and
from altimetrically-derived SSH data, the surface velocity
field is largely in geostrphic balance. In such a case,
the mass flux is nearly non-divergent. For the horizontal
heat advection to be effective in a constant-depth mixed
layer (ML) model, one has to have large horiz. temperature
gradients that are unparallel to the geostrophic
streamfunctions. Because of geostrophy, this effect
is often limited. If the ML depth is allowed to vary
horizontally, this limitation is no longer valid.
One can have, for example in this case, horiz. geostrophic
flow bring in subsurface cold water from one place
(where the ML depth is shallow) into where the ML is
deeper. Because the ML depth is thermodynamically
determined, it is unlikely that they are parallel to
the geostrophic streamlines.
In short, considering a spatially varying ML may "enhance"
the horizontal heat advection effect in the upper ocean
heat budget calculation.