Atmosphere Ocean Science Colloquium

---

The Development of 2015 El Nino and the End of Global Warming "Hiatus"

Speaker: Alexey Fedorov, Yale University

Location: Warren Weaver Hall 1302

Date: Wednesday, February 8, 2017, 3:30 p.m.

Synopsis:

The extreme El Nino of 2015 was part of surprisingly persistent warm conditions in the equatorial Pacific that began in March 2014 and lasted for almost two and a half years. Here I discuss the mechanisms and global impacts of these prolonged El Nino conditions using a combination of observations, GCM experiments and simple modeling. The onset of the warming occurred after a series of strong westerly wind bursts over the western tropical Pacific in early 2014, which generated the initial ocean warming reminiscent of the onset of El Nino in 1997. However, the development of a potentially strong El Nino event stalled, larely due to an exceptionally strong easterly wind burst that occurred in June. Nevertheless, the weak surface warming that developed by year-end and a recharged ocean state created favorable conditions for the continuation of El Nino. Consequently, another series of westerly wind bursts in early 2015 generated a further warming in the central and eastern equatorial Pacific that eventually led to an extreme El Nino event. These warm conditions in the tropical Pacific ocean induced broad surface air temperature anomalies not only in the Pacific but globally as well, resulting in the last three years being the warmest years on record so far and effectively ending the much-discussed global warming "hiatus".