1 / 18

The North Atlantic Oscillation (NAO)

The North Atlantic Oscillation (NAO). Atmospheric Effects of the NAO. NAO + - Strong H and L pressure cells - Westerlies strengthen - Storm track shifts North NAO - -Weak H and L pressure cells - Westerlies weaken - Storm track shifts South.

claire
Download Presentation

The North Atlantic Oscillation (NAO)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The North Atlantic Oscillation(NAO)

  2. Atmospheric Effects of the NAO NAO + - Strong H and L pressure cells - Westerlies strengthen - Storm track shifts North NAO - -Weak H and L pressure cells - Westerlies weaken - Storm track shifts South

  3. North Atlantic Ocean Circulation Responses to the NAO Emphasis on NW Atlantic 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

  4. The Winter NAO Index 4 2 0 -2 -4 1860 1880 1900 1920 1940 1960 1980 2000

  5. Gulf of Maine/Georges Bank Region An oceanographic transition zone especially vulnerable to changes in climate.

  6. NW Atlantic’s Coupled Slope Water System Maximum Modal State - Associated with NAO + Minimum Modal State - Associated with NAO -

  7. The Winter NAO Index 4 2 0 -2 -4 1860 1880 1900 1920 1940 1960 1980 2000

  8. Feb.98 Jan.98 Sep.97 Oct.97 Feb.98 Mar.98 Progress of LSSW along Continental Margin

  9. January April May September October November Intrusions of LSSW into Gulf of Maine

  10. NW Atlantic Response of Calanus finmarchicus to the NAO • C. finmarchicus dominates zooplankton biomass at high latitudes. • Although an oceanic species, C. finmarchicus populations dominate springtime production of many North Atlantic shelf ecosystems, including the Gulf of Maine.

  11. HYPOTHESIS:C. finmarchicus - an indicator of climate-driven changes in ocean circulation? • Since shelf populations of C. finmarchicus are not self-sustaining and must be supplied every year or every few years from external sources, we hypothesize that their fluctuations in abundance reflect climate-driven changes in ocean circulation.

  12. Continuous Plankton Recorder (CPR) Survey of the North Atlantic - SAHFOS supervises CPR surveys throughout most of North Atlantic. - Sister CPR surveys on Scotian Shelf and Gulf of Maine provide comparable plankton time-series data. - Gulf of Maine CPR surveys are conducted by NMFS in Narragansett, RI.

More Related