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The El Niño-Southern Oscillation (ENSO) Modoki signal in the stratosphere

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Zubiaurre, I. and Calvo Fernández, Natalia (2012) The El Niño-Southern Oscillation (ENSO) Modoki signal in the stratosphere. Journal of geophysical research-atmospheres, 117 . ISSN 0148-0227

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Official URL: http://dx.doi.org/10.1029/2011JD016690




Abstract

El Niño-Southern Oscillation (ENSO) is known to be the largest source of interannual variability in the tropical troposphere. However, the variability in the tropical Pacific since 1979 seems to be associated not only with "canonical" ENSO events but also with a variation thereof known as ENSO Modoki, which is characterized by warm anomalies in the central Pacific, west from those occurring during a typical ENSO. This works analyzes the signal of ENSO Modoki in the stratosphere and compares it to canonical ENSO by using the chemistry-climate Whole Atmosphere Community Climate Model (WACCM3.5). The results reveal a significant warming in the Southern Hemisphere polar stratosphere during boreal winter months, which propagates downward in early spring; this is absent during canonical warm ENSO events. On the other hand, in the Northern Hemisphere stratosphere, the anomalous warming typical of canonical El Niño episodes during boreal winter is not statistically significant during El Niño Modoki events. These differences are related in WACCM3.5 to changes in tropical convection and tropospheric teleconnections associated with each type of event. In particular, an enhancement and westward displacement of the anomalous convective area during El Niño Modoki episodes is related to an intensification of the Pacific South American teleconnection pattern and a weakening of the Aleutian Low. During cold ENSO Modoki events a significant anomalous cooling is present in the model simulations.


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Additional Information:

© Copyright 2012 by the American Geophysical Union. The authors are very thankful to Rolando R. Garcia for multiple fruitful discussions of some parts of the manuscript. D. E. Kinnison is also acknowledged for providing the WACCM3.5 simulations used in this study. I. Zubiaurre was supported by the Spanish Ministry of Education and Sciences under TRODIM project. N. Calvo has been supported by the advanced study program from the National Center for Atmospheric Research (ASP-NCAR).

Uncontrolled Keywords:North-Atlantic; Pacific rim; Climate; Events; Winter; Troposphere; Hemisphere; Atmosphere; Patterns; Impact
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
Sciences > Physics > Atmospheric physics
ID Code:25476
Deposited On:23 May 2014 08:00
Last Modified:10 Dec 2018 15:05

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