[OANNES Foro] Late-twentieth-century emergence of the El Niño propagation asymmetry and future projections

[Mario Cabrejos]

Nature 
Volume: 504, Pages: 126-130
doi:10.1038/nature12683
Published online 17 November 2013 
http://www.nature.com/nature/journal/v504/n7478/full/nature12683.html?WT.ec_id=NATURE-20131205
Late-twentieth-century emergence of the El Niño propagation asymmetry and future projections
Agus Santoso1 Shayne McGregor1 Fei-Fei Jin2 Wenju Cai3 Matthew H. England1 Soon-Il An4 Michael J. McPhaden5 Eric Guilyardi6, 7 
1 Australian Research Council (ARC) Centre of Excellence for Climate System Science and Climate Change Research Centre, Level 4 Mathews Building, The University of New South Wales, Sydney 2052, Australia 2 Department of Meteorology, School of Ocean and Earth Science and Technology (SOEST), University of Hawaii at Manoa, 2525 Correa Road, Honolulu, Hawaii 96822, USA 3 Commonwealth Scientific and Industrial Research Organisation (CSIRO), Marine and Atmospheric Research, 107-121 Station Street, Aspendale, Victoria 3195, Australia 4 Department of Atmospheric Sciences, Yonsei University, 50 Yonsei-ro, Seodaemun-Gu, Seoul 120-749, South Korea 5 National Oceanic and Atmospheric Administration (NOAA)/Pacific Marine Environmental Laboratory, Seattle, Washington 98115, USA 6 Laboratoire d'Océanographie et du Climat: Expérimentation et Approches Numériques/Institut Pierre Simon Laplace (IPSL)/Centre national de la recherché scientifique (CNRS), tour 45-55, étage 4, pièce 406, Université Pierre et Marie Curie, 4 Jussieu, 75252 Paris Cedex 05, France 7 National Centre for Atmospheric Science (NCAS)-Climate, Department of Meteorology, University of Reading, Earley Gate, Reading RG6 6BB, UK

SUMMARY

The El Niño/Southern Oscillation (ENSO) is the Earth's most prominent source of interannual climate variability, exerting profound worldwide effects1, 2, 3, 4, 5, 6, 7. Despite decades of research, its behaviour continues to challenge scientists. In the eastern equatorial Pacific Ocean, the anomalously cool sea surface temperatures (SSTs) found during La Niña events and the warm waters of modest El Niño events both propagate westwards, as in the seasonal cycle7. In contrast, SST anomalies propagate eastwards during extreme El Niño events, prominently in the post-1976 period7, 8, 9, 10, spurring unusual weather events worldwide with costly consequences3, 4, 5, 6, 11. The cause of this propagation asymmetry is currently unknown10. Here we trace the cause of the asymmetry to the variations in upper ocean currents in the equatorial Pacific, whereby the westward-flowing currents are enhanced during La Niña events but reversed during extreme El Niño events. Our results highlight that propagation asymmetry is favoured when the westward mean equatorial currents weaken, as is projected to be the case under global warming12, 13, 14. By analysing past and future climate simulations of an ensemble of models with more realistic propagation, we find a doubling in the occurrences of El Niño events that feature prominent eastward propagation characteristics in a warmer world. Our analysis thus suggests that more frequent emergence of propagation asymmetry will be an indication of the Earth's warming climate.
------------ próxima parte ------------
Se ha borrado un adjunto en formato HTML...
URL: <http://lista.oannes.org.pe/pipermail/oannes-oannes.org.pe/attachments/20140110/e258331b/attachment.html>