Geophysikalisches Kolloquium: Simulated variability of the North Atlantic circulation from 1953 to 2003

The Atlantic meridional overturning circulation has an important influence on the Atlantic - european climate, and it is thus of interest to understand its mechanisms of variability. A hindcast simulation of the North Atlantic circulation suggests that the subpolar gyre and the meridional overturning circulation have intensified from the late 1960’s to the mid-1990’s and then decreased. The changes are largely due to the influence of the North Atlantic Oscillation (NAO), in particular via its impact on deep convection in the Labrador and the Irminger Seas. The former is mostly influenced by the surface heat exchanges associated with the NAO, while the latter primarily responds to the dooming of isopycnals. It will be shown that the Atlantic meridional overturning circulation in the model primarily responds as an integrator of deep convection changes in the Irminger Sea, and that the meridional overturning circulation changes precede those in the gyre circulation. The role of salinity will also be discussed.




15:15 h


Geomatikum H4
Lecture hall H4 (ground floor), University of Hamburg, Bundesstr. 55, Hamburg


Claude Frankignoul, Université Pierre et Marie Curie,


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