Sub-seasonal wind events and El Niño

Abstract:

It is widely recognized that El Niño events influence global seasonal weather anomalies in many regions and seasons, and that knowledge of ENSO state can provide useful forecasts in regions where the influence is strong and consistent enough from event-to-event. Despite the considerable advances made in the last thirty years of ENSO study, serious challenges still remain in predicting the trajectory of ENSO state (particularly from neutral conditions) and in forecasting the year-to-year weather anomalies seen among the commonly identified El Niño years. The variability of the tropical Pacific in recent years, such as 2012 and 2014, whose early to mid-year anomaly conditions prompted many to forecast the development of El Niño events, highlights the ability of sub-seasonal winds to affect that development. We offer some recent research results on the role that sub-seasonal wind events play in the initiation and growth of different types of ENSO events, with focus on their prolonged effects on the development of sea surface temperature (SST) anomalies in the Pacific oceanic waveguide and impacts on seasonal weather anomalies elsewhere.