Possible oceanic feedback in the extratropics in relation to the North Atlantic SST tripole
Article first published online: 14 MAR 2009
Copyright 2009 by the American Geophysical Union.
Geophysical Research Letters
Volume 36, Issue 5, March 2009
How to Cite
2009), Possible oceanic feedback in the extratropics in relation to the North Atlantic SST tripole, Geophys. Res. Lett., 36, L05710, doi:10.1029/2008GL036781., , and (
- Issue published online: 14 MAR 2009
- Article first published online: 14 MAR 2009
- Manuscript Accepted: 10 FEB 2009
- Manuscript Revised: 5 FEB 2009
- Manuscript Received: 24 NOV 2008
- oceanic feedback;
- North Atlantic SST tripole;
- North Atlantic Oscillation
 We analyze the results of 4-dimensional variational data assimilation experiments using a coupled general circulation model and identify signals from a possible extratropical oceanic feedback relating to the North Atlantic Sea Surface Temperature (SST) tripole. Examination of the optimized control variables (coupling parameters) and the resultant climate fields reveals that the model errors in the North Atlantic climate variations are very sensitive to the intensity of the extratropical air-sea thermal coupling. This results in the enhancement of the atmospheric responses to SST changes particularly around 40°N, 50°W, when the model errors are most effectively corrected. Since an adjoint approach enables us to detect the sensitivity to fluctuations in the model variables, our results suggest that this oceanic thermal feedback in the extratropics is a key physical process influencing the North Atlantic Oscillation and the associated North Atlantic SST tripole.