•“One of the most prominent teleconnection patterns in all seasons is the North Atlantic Oscillation (NAO) (Barnston and Livezey 1987). The NAO combines parts of the East-Atlantic and West Atlantic patterns originally identified by Wallace and Gutzler (1981) for the winter season.” (Climate Prediction Center (CPC))
•Positive Phase: below (above) normal heights and pressures across N. Atlantic (central N. Atlantic) (CPC)
•Negative Phase: pattern opposite positive phase (CPC)
•Both phases influence (1) the intensity and location of the North Atlantic jet stream and (2) zonal and meridional heat and moisture transport
(CPC)
NAP - "The NAO is the dominant mode of winter climate variability in the North Atlantic region ranging from central North America to Europe and much into Northern Asia. The NAO is a large scale seesaw in atmospheric mass between the subtropical high and the polar low. The corresponding index varies from year to year, but also exhibits a tendency to remain in one phase for intervals lasting several years."
source -
http://www.ldeo.columbia.edu/res/pi/NAO/
