TITLE:      9 Years of WAP (1993-2001) LTER Physical Oceanography: Water Mass
            Distributions (talk) given at the 
	    Fourth U.S. Southern Ocean Globec Science Investigator Meeting
AUTHORS:    Douglas G. Martinson
DATE:       9-11 December 2002
PLACE:      Arlington, VA
Posted WEB: http://www.ccpo.odu.edu/Research/globec/4sciinvest/martinson.htm

Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, 10964
(dgm@ldeo.columbia.edu)

ABSTRACT

This presentation presents the results of a water mass analysis of the
1993-2001 Palmer LTER hydrography data base. The analysis is intended to
provide a longer term and broader scale context for the recent S.O. GLOBEC 
surveys. The water mass distributions show the following: (1)  the WAP region
is characterized by typical circumpolar water masses, though their signature 
in T-S space is slightly different on the slope (sharp V shape) relative to 
that on the shelf (U-shape); (2) the rapid erosion of the winter water (WW) 
by mixing, but the sharp regularity (defining the V shape) of the WW in T-S 
plots indicates that the ACC waters regularly sweep the continental slope and
episodically floods the shelf, replacing modified shelf and coastal waters 
with typical circumpolar waters, while flushing the modified waters back 
into the circumpolar current; (3) freshening of the shelf waters from summer 
sea ice melt sets the surface water conditions for the following winter; (4)
the ACC water sweeping the slope and shelf seems most consistent historically 
with waters flowing in from approximately 66-70 degrees S (80-100? W); (5) 
despite considerable interannual variability in the vertical placement of the
key water masses, they show sub-regional consistency in T-S space over the 
years; (6) the seasonal evolution of the water column is evident through the
quick seasonal evolution of the water mass properties, even as deep as in the
CDW, suggesting strong vertical (and perhaps lateral) mixing, e.g., the WW
warms and salinates quickly through winter along, and the entire slope of the 
permanent pycnocline waters in T-S space changes to accommodate this warming.
This change in permanent pycnocline slope indicates how deep and intense the 
vertical mixing  a volumetric heat and salt budget suggests that the 
differences can be achieved by vertical mixing with strong mixing coefficients 
as one might expect over the slope and shelf regions (consistent with Smith 
and Klinck, DSR, 2002).