North Atlantic Ocean Circulation Responses to the NAO
NAO +
- Enhanced production of LSW and
   intensification of DWBC
- Labrador Current weakens
- Gulf Stream north wall shifts North
NAO -
- Reduced production of LSW and
   weakening of DWBC
- Labrador Current  intensifies
- Gulf Stream north wall shifts South
Emphasis on NW Atlantic
The atmospheric changes occur over the major deepwater formation regions in the Atlantic.  Deepwater production requires cold conditions which produce very dense water.  When the NAO is +, the Labrador Sea is cold which creates ideal conditions for deepwater formation.  When the NAO shifts, the deepwater formation in the LS diminishes, but increases in the Greenland Sea.

The changes in water mass distribution and the winds lead to changes in the circulation of the Atlantic; however, the changes are typically delayed by a year or more.  In the western atlantic, the Gulf Stream shifts south during NAO- at the same time as the Labrador Current intensifies and extends.  In the east, there is evidence that a warm coastal jet extends during NAO+