The complex behavior of El Niño winter 2015-2016

• Main Authors: Palmeiro, Froila M., Iza, M., Barriopedro, David, Calvo, N., García Herrera, Ricardo
• Other Authors: Ministerio de Economía y Competitividad (España), European Commission
• Format: Conference Object
• Language: English
• Published: 2017
• Subjects: Española; Greenland; Pacific; aleutian low
• Online Access: http://hdl.handle.net/10261/188994; https://doi.org/10.13039/501100000780; https://doi.org/10.13039/501100003329

Trabajo presentado a la XXXVI Reunión Bienal de la Real Sociedad Española de Física, celebrada en Santiago de Compostela (España) del 17 al 21 de julio de 2017. In this study we examine the outstanding characteristics of the strong 2015–2016 El Niño (EN), one of the strongest in record, and its impact over the European region through the stratospheric pathway. Despite being classified as a strong eastern Pacific (EP) EN event, our analysis reveals its complex nature, with some signatures that are more typical of central Pacific (CP) EN events instead. The CP-EN behavior of this event is based on first, the value of the CP index, which reached a historical record. Second, the polar stratospheric signal, as a stronger and colder polar vortex in early and mid-winter in relation to reduced upward wave propagation and a weak Aleutian low; which resembles the typical behavior reported for CP-EN. Third, the occurrence of one of the earliest Stratospheric Final Warmings (SFWs) on record; which are found to be more prone to occur during CP-EN than EP-EN events. In addition, anomalies following the SFW descended from the stratosphere into the troposphere and influenced the surface weather during spring. Thus, persistent blocking conditions over Greenland diverted the Atlantic storm-tracks to the south, resulting in above-normal precipitation over southern Europe. These results highlight the importance of considering early SFWs as mediators in El Niño teleconnections. This work was supported by the Spanish Ministry of Economy and Competitiveness through the PALEOSTRAT (CGL2015-69699-R) project and the European Project 603557-STRATOCLIM under program FP7-ENV.2013.6.1-2. F.M. Palmeiro was funded by grant BES-2013-063906 Peer reviewed