Posted by Randy Watts on November 06, 2000 at 21:27:03:
In Reply to: ABYSSAL "STORMS" = NEARLY BAROTROPIC - IZZAT CLEAR? posted by Watts on March 31, 2000 at 12:38:20:
: Question for poster visitors after visiting the site:
: Was it made clear ednough to you that the color-coded
: cyclones and anticyclones (which we measured at 3500 dbar)
: are REALLY nearly depth-independent?
: i.e. they exert important
: influence up thru the thermocline to the sea surface
: (thus driving important cross-frontal exchange, which is
: the topic of the Lindstrom papers (see Bibliog).
: There are two good ways to appreciate the barotropic
: (nearly depth-independent) nature
: of these "storms":
: (1) the Savidge and Bane citations study this issue;
: (2) the upper Gulf Stream shear adds to but does not
: erase these deep ('reference') velocities, which therefore
: extend up through the whole water column. Summed together,
: the current turns with height, as is also observed in the
: atmospheric jet stream. Meteorologists call this turning
: "backing" or "veering".
Commenting on this and on Qiu's preceeding comment!
I want to draw an important distinction between
calling the abyssal storms "nearly barotropic", which
they ARE because they exert their influence all the way
up through the water column,
VERSUS calling the Gulf Stream meanders "equivalent
barotropic", which they are NOT. The abyssal storms
are phase-offset (vertically tilted) from the
meandering baroclinic front. One can mentally
partition the current into the vector sum of
1. a meandering front which is nearly equivalent barotropic, plus
2. an abyssal storm which is nearly independent of depth.
Because these two parts are horizontally phase-offset
and turned, their vector sum turns with depth.