[Source: NOAA Climate Prediction Center, http://www.cpc.ncep.noaa.gov/
The East Atlantic (EA) pattern is the second of three prominent modes of low-frequency variability over the North Atlantic, appearing in all months except May-August. The pattern is structurally similar to the NAO, and consists of a north-south dipole of anomaly centers which span the entire North Atlantic Ocean from east to ... west. However, the anomaly centers in the EA pattern are displaced southeastward to the approximate nodal lines of the NAO pattern. For this reason, the EA pattern is often mistaken as simply a slightly `southward-shifted' NAO pattern. Also, the lower-latitude center contains a strong subtropical link, reflecting large-scale modulations in the strength and location of the subtropical ridge. This subtropical link also makes the EA pattern distinct from its NAO counterpart. This EA pattern is similar to that shown in the Barnston and Livezey (1987) study, but is distinctly different from the EA pattern originally defined by Wallace and Gutzler (1981).