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Mardi 9 octobre - Changes in the deep water circulation of the Arctic Ocean during the last 30 years inferred from the distribution of 230Th in the water column

by SEMSOU last modified Feb 12, 2013 12:31 PM
When Sep 09, 2012
from 11:00 AM to 01:00 PM
Where Coriolis
Contact Name
Attendees Roger Francois (UBC)
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Roger Francois (UBC)

 

Titre :

Changes in the deep water circulation of the Arctic Ocean during the last 30 years inferred from the distribution of 230Th in the water column


Résumé :

Dissolved 230Th was first measured in the water column of the Arctic Ocean in 1983 from an ice camp over Alpha Ridge (Bacon et al., 1989). Subsequently, an additional 22 profiles were measured at various locations between 1987 and 2009 in the Eurasian and Canadian Basins (Cochran et al., 1995; Scholten et al., 1995; Edmonds et al., 1998; 2004; Francois et al., unpub.). These profiles can be compared in space and time to infer changes in the deep water circulation of the Arctic Ocean. In particular, it can be shown that, prior to the early 1990’s, a water mass remained largely isolated from the general circulation of the Arctic Ocean, under permanent ice cover over Alpha Ridge and in northern Makarov Basin. This relative isolation is based on the very high dissolved 230Th concentrations measured at these two locations in 1983 and 1991, respectively. In the mid-1990’s, the pattern of Arctic deep water circulation started to change, resulting in the displacement of this previously isolated water mass into the surrounding basins, first in the Norwegian Sea, and most recently in Canada Basin. These data further illustrate the potential of 230Th as a powerful, yet rarely used, tracer of deep water circulation.

 

 

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