Posted by Bo Qiu on September 20, 2000 at 13:57:10:
One of the scientifically exciting results from the SYNOP program
is the finding of the equivalent barotropic nature associated with
the troughs of the meandering Gulf Stream. For those of us who
studied the western boundary current variability largely using
near-surface observational data, it is both fascinating and
eye-opening to read the poster by Watts et al. and to see the rapid
evolution (and the slow evolution, if one prefers that mode on
their well-designed website) of the abyssal "storms" captured by
the unprecedented SYNOP observations. Watts et al.'s poster
convincingly shows that rather than being forced passively by the
baroclinic instability of the surface-intensified Gulf Stream, these
equivalent barotropic eddies not only affect cross-frontal exchanges,
but may also determine the time scales of the evolution of the
meandering Gulf Stream.
There are two related issues I found rather intriguing after
viewing the poster:
(1) Abyssal cyclones/anticyclones: The chosen site for the SYNOP
Central Array appears to be dominated by troughs of the meandering
Gulf Stream. In other words, there are more abyssal cyclones than
anticyclones. Do we know why this happens to be the case? The
topography map indicates that the array is partially overriding an
abyssal canyon. Does this local bottom topography contribute to
the preference of the local persistent Gulf Stream troughs?
(2) Warm core rings: The formation process for a WCR described
in the poster is very interesting. This may be related to the above
point in that the meandering troughs at this site are so much more
energetic than the meandering crests, so that the resultant barotropic
cyclones are able to swirl the weaker anticyclones northward and
cause their pinching-off eventually. Is the SYNOP Central Array
site a preferred location for the WCR formation?