Atmospheric Blocking and Atlantic Multidecadal Ocean Variability
- 1National Aeronautics and Space Administration (NASA) Goddard Space Flight Center, Code 615, Greenbelt, MD 20771, USA.
- 2University of Washington, Box 357940, Seattle, WA 98195, USA.
- 3Wyle Information Systems/NASA Goddard Space Flight Center, Code 615, Greenbelt, MD 20771, USA.
- ↵*To whom correspondence should be addressed. E-mail: sirpa.hakkinen{at}nasa.gov
Abstract
Atmospheric blocking over the northern North Atlantic, which involves isolation of large regions of air from the westerly circulation for 5 days or more, influences fundamentally the ocean circulation and upper ocean properties by affecting wind patterns. Winters with clusters of more frequent blocking between Greenland and western Europe correspond to a warmer, more saline subpolar ocean. The correspondence between blocked westerly winds and warm ocean holds in recent decadal episodes (especially 1996 to 2010). It also describes much longer time scale Atlantic multidecadal ocean variability (AMV), including the extreme pre–greenhouse-gas northern warming of the 1930s to 1960s. The space-time structure of the wind forcing associated with a blocked regime leads to weaker ocean gyres and weaker heat exchange, both of which contribute to the warm phase of AMV.
- Received for publication 16 March 2011.
- Accepted for publication 21 September 2011.
