North Atlantic Oscillation
Seeing the big picture in the Gulf of Maine

5. Warm or cold offshore water masses can enter the Northeast Channel

• Two water masses called the Labrador Slope Water and Warm Slope Water occupy the continental slope of North America.
• The water masses differ in temperature, salinity, nutrients, and nutrient ratios.
• Depending on the NAO, either can penetrate the Northeast Channel, affecting conditions in the Gulf of Maine.

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High NAO Index A high NAO index brings Warm Slope Water toward the Northeast Channel. This carries warm, salty water into the Gulf of Maine.

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Low NAO Index A low NAO index brings the Labrador Current toward the Northeast Channel. This carries cold, relatively fresh water into the Gulf of Maine. Images: Chris Brehme re-created from image by K. Drinkwater, Bedford Institute of Oceanography

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1.Seeing the big picture: Introduction
2.Offshore buoys are sentinels of change
3.GoMOOS monitors currents entering the Gulf Of Maine
4."El Niño of the Atlantic" affects the incoming currents
5.Warm or cold currents can penetrate the Northeast Channel
6.Case study: Cold water invades the Gulf of Maine
7.Ripple effects reach bays and estuaries
Acknowledgements