Exceptionally strong easterly wind burst stalling El Niño of 2014

Significance The El Niño–Southern Oscillation is the dominant mode of climate variability in the tropical Pacific, with pronounced global teleconnections. Predicting El Niño and understanding its progression still present a challenge to climate scientists. At the beginning of 2014, many in the scientific community anticipated that a strong El Niño could potentially develop by year end, but the observed warm event barely reached the El Niño threshold. Here, we analyze satellite-based data and numerical simulations to show that an intense easterly wind burst that occurred in June of 2014 was the key dynamical factor that stalled the El Niño development. We discuss our findings in the context of limited El Niño predictability and explore links between intraseasonal wind bursts and decadal climate change. Intraseasonal wind bursts in the tropical Pacific are believed to affect the evolution and diversity of El Niño events. In particular, the occurrence of two strong westerly wind bursts (WWBs) in early 2014 apparently pushed the ocean–atmosphere system toward a moderate to strong El Niño—potentially an extreme event according to some climate models. However, the event’s progression quickly stalled, and the warming remained very weak throughout the year. Here, we find that the occurrence of an unusually strong basin-wide easterly wind burst (EWB) in June was a key factor that impeded the El Niño development. It was shortly after this EWB that all major Niño indices fell rapidly to near-normal values; a modest growth resumed only later in the year. The easterly burst and the weakness of subsequent WWBs resulted in the persistence of two separate warming centers in the central and eastern equatorial Pacific, suppressing the positive Bjerknes feedback critical for El Niño. Experiments with a climate model with superimposed wind bursts support these conclusions, pointing to inherent limits in El Niño predictability. Furthermore, we show that the spatial structure of the easterly burst matches that of the observed decadal trend in wind stress in the tropical Pacific, suggesting potential links between intraseasonal wind bursts and decadal climate variations.

[1]  Yu Kosaka,et al.  Recent global-warming hiatus tied to equatorial Pacific surface cooling , 2013, Nature.

[2]  Y. Masumoto,et al.  Indian Ocean warming modulates Pacific climate change , 2012, Proceedings of the National Academy of Sciences.

[3]  Bin Wang,et al.  Abrupt termination of the 2012 Pacific warming and its implication on ENSO prediction , 2014 .

[4]  Shlomo Havlin,et al.  Very early warning of next El Niño , 2014, Proceedings of the National Academy of Sciences.

[5]  Matthieu Lengaigne,et al.  About the role of Westerly Wind Events in the possible development of an El Niño in 2014 , 2014 .

[6]  B. Kirtman,et al.  Westerly wind bursts and the diversity of ENSO in CCSM3 and CCSM4 , 2013 .

[7]  H. Kao,et al.  Contrasting Eastern-Pacific and Central-Pacific Types of ENSO , 2009 .

[8]  E. Guilyardi,et al.  UNDERSTANDING EL NINO IN OCEAN-ATMOSPHERE GENERAL CIRCULATION MODELS : Progress and Challenges , 2008 .

[9]  E. Guilyardi,et al.  The impact of westerly wind bursts and ocean initial state on the development, and diversity of El Niño events , 2015, Climate Dynamics.

[10]  D. E. Harrison,et al.  Pre- and Post-1997/98 Westerly Wind Events and Equatorial Pacific Cold Tongue Warming* , 2008 .

[11]  Incorporating a semi-stochastic model of ocean-modulated westerly wind bursts into an ENSO prediction model , 2009 .

[12]  Mojib Latif,et al.  Predictability of a Stochastically Forced Hybrid Coupled Model of El Niño , 1997 .

[13]  Agus Santoso,et al.  Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus , 2014 .

[14]  Fei-Fei Jin,et al.  An Equatorial Ocean Recharge Paradigm for ENSO. Part II: A Stripped-Down Coupled Model , 1997 .

[15]  S. Xie,et al.  Seasonality of tropical Pacific decadal trends associated with the 21st century global warming hiatus , 2015 .

[16]  A. Fedorov,et al.  The response of the coupled tropical ocean–atmosphere to westerly wind bursts , 2002 .

[17]  A. Capotondi.  ENSO diversity in the NCAR CCSM4 climate model , 2013 .

[18]  B. Kirtman,et al.  El Niño in a changing climate , 2009, Nature.

[19]  Matthieu Lengaigne,et al.  Triggering of El Niño by westerly wind events in a coupled general circulation model , 2004 .

[20]  E. Tziperman,et al.  Author's Personal Copy Dynamics of Atmospheres and Oceans Impact of Interactive Westerly Wind Bursts on Ccsm3 Author's Personal Copy , 2022 .

[21]  M. Mcphaden.  A 21st century shift in the relationship between ENSO SST and warm water volume anomalies , 2012 .

[22]  D. E. Harrison,et al.  Westerly Wind Events in the Tropical Pacific, 1986–95* , 1997 .

[23]  J. Tollefson.  El Niño tests forecasters , 2014, Nature.

[24]  Fei-Fei Jin,et al.  An Equatorial Ocean Recharge Paradigm for ENSO. Part I: Conceptual Model , 1997 .

[25]  Andrew T. Wittenberg,et al.  How Predictable is El Niño , 2003 .

[26]  M. Latif,et al.  El Niño/Southern Oscillation response to global warming , 2009, Proceedings of the National Academy of Sciences.

[27]  Dake Chen,et al.  Effects of westerly wind bursts on El Niño: A new perspective , 2014 .

[28]  D. E. Harrison,et al.  Equatorial Pacific Easterly Wind Surges and the Onset of La Niña Events , 2015 .

[29]  M. Mcphaden,et al.  Genesis and evolution of the 1997-98 El Nino , 1999, Science.

[30]  D. Chelton,et al.  Satellite Measurements Reveal Persistent Small-Scale Features in Ocean Winds , 2004, Science.

[31]  A. Timmermann,et al.  Recent Walker circulation strengthening and Pacific cooling amplified by Atlantic warming , 2014 .

[32]  Andrew T. Wittenberg,et al.  Warm Pool and Cold Tongue El Nino Events as Simulated by the GFDL 2.1 Coupled GCM , 2010 .

[33]  D. Gutzler,et al.  Estimating the Effect of Stochastic Wind Stress Forcing on ENSO Irregularity , 1997 .

[34]  Jong,et al.  Two Types of El Niño Events: Cold Tongue El Niño and Warm Pool El Niño , 2009 .

[35]  E. Guilyardi,et al.  Understanding ENSO Diversity , 2015 .

[36]  E. Tziperman,et al.  Modulation of Westerly Wind Bursts by Sea Surface Temperature: A Semistochastic Feedback for ENSO , 2007 .

[37]  Christophe Cassou,et al.  Importance of oceanic decadal trends and westerly wind bursts for forecasting El Niño , 2000 .

[38]  Eli Tziperman,et al.  Westerly Wind Bursts: ENSO's tail rather than the dog? , 2004 .

[39]  P. Delecluse,et al.  Westerly Wind Events in the Tropical Pacific and their Influence on the Coupled Ocean‐Atmosphere System: A Review , 2013 .

[40]  E. Guilyardi,et al.  The impact of westerly wind bursts on the diversity and predictability of El Niño events: An ocean energetics perspective , 2014 .

[41]  Andrew M. Moore,et al.  A Theory for the Limitation of ENSO Predictability Due to Stochastic Atmospheric Transients , 1997 .

[42]  Heikki Kauppi,et al.  Reconciling anthropogenic climate change with observed temperature 1998–2008 , 2011, Proceedings of the National Academy of Sciences.

[43]  L. Hartten.  Synoptic settings of westerly wind bursts , 1996 .

[44]  E. Guilyardi,et al.  Processes driving intraseasonal displacements of the eastern edge of the warm pool: the contribution of westerly wind events , 2015, Climate Dynamics.

[45]  E. Guilyardi,et al.  Modulation of equatorial Pacific westerly/easterly wind events by the Madden–Julian oscillation and convectively-coupled Rossby waves , 2016, Climate Dynamics.

[46]  Adam S. Phillips,et al.  ENSO and Pacific Decadal Variability in the Community Climate System Model Version 4 , 2012 .

[47]  J. Bjerknes.  ATMOSPHERIC TELECONNECTIONS FROM THE EQUATORIAL PACIFIC1 , 1969 .