Diversity of North Pacific Meridional Mode and Its Distinct Impacts on El Niño-Southern Oscillation

Numerous studies have demonstrated that the North Pacific Meridional Mode (NPMM) plays an important role in determining El Niño-Southern Oscillation (ENSO) events in the following winter season. However, little attention has been given to significant differences among its spatial patterns. Here we show that the NPMM exhibits a large diversity in spatial patterns, leading to distinct impacts on ENSO. Based on objective clustering analysis, two distinct spatial patterns of NPMM are detected. Cluster 1 (C1) NPMM exhibits a strong sea surface temperature dipole over the subtropical eastern Pacific and midlatitude central Pacific whereas Cluster 2 (C2) features a dipole over the subtropical eastern Pacific and equatorial cold tongue region. We find that the C1 NPMM is strongly linked to following ENSO events while the C2 NPMM has no statistically significant relation. This gives new implications for ENSO dynamics and predictions.