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Sunday, October 14, 2012

Tuggweilder and Samuels, 1994, Effect of the Drake Passage on Global Thermohaline Circulation

Abstract-The Ekman divergence around Antarctica raises a large amount of deep water to the
ocean’s surface. The regional Ekman transport moves the upwelled deep water northward out of
the circumpolar zone. The divergence and northward surface drift combine, in effect, to remove
deep water from the interior of the ocean. This wind-driven removal process is facilitated by a
unique dynamic constraint operating in the latitude band containing Drake Passage. Through a
simple model sensitivity experiment WC show that the upwelling and removal of deep water in the
circumpolar belt may be quantitatively related to the formation of new deep water in the northern
North Atlantic. These results show that stronger winds in the south can induct more deep water
formation in the north and more deep outflow through the South Atlantic. The fact that winds in
the southern hemisphere might influence the formation of deep water in the North Atlantic brings
into question long-standing notions about the forces that drive the ocean’s thermohaline circulation.

Is a must read if you want any insight into longer term global climate.  The drawing which is reproduced without permission, so should the holder of the rights be offended, I will remove, but it is a very educational drawing.   The Antarctic Convergence is more than just an ocean convergence, it is an upper ocean, deep ocean, atmospheric, thermally isolated Antarctic, radiant window to space convergence zone, which is modulated by the Drake Passage Current and southern hemisphere atmospheric and sea ice dynamics.  It is the cheese in the "big cheese" of climate regulation.  The source of the 4C deep ocean heat content borders a ~2C mixed ACC band with the mystereous <0 C source of the true abysmal depths sliding down the rock face of the continent of Antarctica.  Small changes in weather patterns and sea ice extent can cause a 2 C change in temperature from 55S to 45S in a fairly short time period.  That shift would change the average temperature and downward pressure on the 4C deep water supply for the THC with impacts that would be felt many decades in the future.


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