Atlantic Multidecadal Oscillation (AMO)

The Atlantic Multidecadal Oscillation (AMO) index reflects an argued 50-80 year pattern of North Atlantic coupled ocean-atmosphere variability. It is associated with changes in rainfall over North America and Europe, the frequency of North American droughts, and the intensity of North Atlantic hurricanes. It may mask or exaggerate signals of global change, though the argument that it is a separate signal from the forced global change signal is disputed.

The term was introduced in a summary of the Delworth and Mann (2000) study by Kerr (2000), which can be found at the Science Web site. The index was defined by Enfield, Mestas-Nuñez, and Trimble (Geophys. Res. Lett., 2001) as the North Atlantic SST anomaly north of the equator. NOAA/AOML has further information on their AMO Web page »

In the shorter series case, monthly averages are shown by the plus signs and 3-month running mean filtered index values are shown by the shaded regions. In the longer series case, 3-month averages are shown by the plus signs and 12-month running mean filtered index values are shown by the shaded regions. The monthly standard deviation of the index over the period 1948-2005 is indicated on each plot. get series (netcdf 12kB) »

Data source and calculation

Calculated by NOAA/ESRL (CDC) (last update 15-JAN-2023).