The Rogers (1984) North Atlantic Oscillation Index (1874-2005)

The North Atlantic Oscillation is the opposition noted in sea level pressures in every month of the year between the subtropical and subpolar Atlantic. The varying gradient of pressure between these regions is a measure of the strength of the North Atlantic westerlies. This website contains the following information:

• Ponta Delgada (Horta/Santa Maria), Azores - monthly/seasonal mean sea level pressure and anomalies
  
• Akureyri, Iceland - monthly/seasonal mean sea level pressure and anomalies
  
• Raw monthly index
  
• Raw seasonal index
  
• Normalized monthly index
  
• Normalized seasonal index