Tropical and North Pacific coupling at decadal timescales shapes basin variability and marine heatwaves

Although Pacific decadal variability is often described in terms of processes operating separately in the tropics and North Pacific, interactions between these two regions are also potentially important but are not well understood. Using 60 years of monthly sea surface temperature and height reanalysis data, here we investigate a dynamical mode with a spatial pattern extending from the Northeast Pacific to the Central equatorial Pacific, the “North Pacific-Central Pacific” mode. We show that this mode accounts for a large fraction of decadal variance in both tropical and North Pacific regions and appears to encapsulate tropical-North Pacific coupled dynamics. We also show that the unprecedented intensity and duration of Northeast Pacific marine heatwaves in recent decades was primarily associated with enhanced variability of this mode, while sea surface temperature variations at interannual timescales in the equatorial Pacific did not play any significant role. Increased understanding of this mode may improve assessments of decadal predictability and aid prediction of Northeast Pacific marine heatwaves. The North Pacific - Central Pacific climate mode accounts for a large fraction of decadal variance in both tropical and North Pacific regions, according to analysis of sea surface temperature and height data.