The Continuum of Northeast Pacific Marine Heatwaves and Their Relationship to the Tropical Pacific
Tongtong Xu, Matthew Newman, Antonietta Capotondi, Emanuele Di Lorenzo
Abstract
Abstract Some questions remain concerning the record‐breaking 2013–2015 Northeast Pacific marine heatwave (MHW) event: was it exceptional or merely the most pronounced of a group of similar events, and was its intensity and multiyear duration driven by internal extratropical processes or did the tropics play an important role? By analyzing the statistical behavior of the historical MHWs within the ERSST.v3 data set over the 1950–2019 period, we find that Northeast Pacific MHWs occurred over a continuum of intensities and durations, suggesting that these events are a recurrent Pacific phenomenon. These statistics and corresponding composite evolution are dynamically reproduced by a large ensemble simulation of a Pacific Linear Inverse Model, thereby providing a greater range of MHW expressions than the short observational record alone. Consistent with the 2013–2015 event's evolution, we find that overall the tropics influence MHWs primarily by increasing their duration, while MHW intensity is related to the initial extratropical anomalies.