The complex behavior of El Niño winter 2015-2016
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2017
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American Geophysical Union
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Abstract
This paper examines the outstanding characteristics of the strong 2015-2016 El Nino (EN) winter and its impact over the European region through the stratosphere. Despite being classified as a strong eastern Pacific (EP) EN event, our analysis reveals an anomalous behavior, with some signatures that are more typical of central Pacific (CP) EN events instead. They include (i) a record-breaking value of the CP index, (ii) a stronger polar vortex in early and midwinter, due to reduced upward wave activity and a weakened Aleutian low, and (iii) the occurrence of one of the earliest stratospheric final warmings (SFWs) on record, which are more prone to occur during CP-EN. Following the SFW, a stratospheric influence on the Euro-Atlantic sector is reported in spring, with persistent Greenland blocking resulting in extreme precipitation over some southern European regions. Results highlight the importance of considering early SFWs as mediators of El Nino teleconnections.
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©2017. American Geophysical Union. All Rights Reserved. We acknowledge the ECMWF for providing ERA-40 and ERA-Interim reanalysis data (http://apps.ecmwf.int/datasets/), the Global Precipitation Climatology Centre for the precipitation data (ftp://ftp-anon.dwd.de/pub/data/gpcc/html/download_gate.html), and the Met Office Hadley Centre for the HadISST1 data (http://www.metoffice.gov.uk/hadobs/hadisst/data/download.html). We thank Kate Willett and an anonymous reviewer for their helpful comments. 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.