North Atlantic Oscillation (NAO)

Pattern of variability in the North Atlantic.

Postive Phase:

Calculation Method:
The indices are based on centers-of-action of 500mb height patterns. These time series utilize the NCEP/NCAR R1 dataset. The area averaged region 55-70N;70W-10W is subtracted from 35-45N; 70W-10W. The 1981-2010 period was used as climatology. Before computing these indices the 500mb height fields are spectrally truncated to total wavenumber 10 in order to emphasize large-scale aspects of the teleconnections.
Time Interval: Daily
Time Coverage: 1948-near present
Update Status: Daily
Get Data:
NAO Timeseries
Data is from NOAA/ESRL PSL
Monthly NAO (different source)
NOAA/CPC's NAO Information