The relationship between the North Atlantic Oscillation and El Niño‐Southern Oscillation

We have applied a multiresolution cross‐spectral analysis technique to resolve the temporal relationship between the NAO and ENSO. The study shows significant coherence between NAO and Niño3 SST in about 70% of the warm ENSO events from 1900 to 1995, of which 33% and 37% are associated with a 5‐ to 6‐year period (E1) and a 2‐ to 4‐year period (E2) oscillation terms in the spectral decomposition, respectively. The dominant teleconnection pattern associated with changes in the mean atmospheric circulation during the initial winter of a typical E1 and E2 events is the positive phase of the Pacific/North American (PNA) pattern. Non‐coherence between the NAO and ENSO occurs during relatively weak Niño3 SST anomaly, with a teleconnection pattern which shows a strong negative phase of the NAO and a pattern which resembles a weak eastward shifted negative phase of the PNA pattern.