All flavours of El Nino have similar early subsurface origins

Ramesh, Nandini and Murtugudde, Raghu (2012) All flavours of El Nino have similar early subsurface origins. In: NATURE CLIMATE CHANGE, 2 .

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Abstract

The El Nino/Southern Oscillation phenomenon, characterized by anomalous sea surface temperatures and winds in the tropical Pacific, affects climate across the globe(1). El Ninos occur every 2-7 years, whereas the El Nino/Southern Oscillation itself varies on decadal timescales in frequency and amplitude, with a different spatial pattern of surface anomalies(2) each time the tropical Pacific undergoes a regime shift. Recent work has shown that Bjerknes feedback(3,4) (coupling of the atmosphere and the ocean through changes in equatorial winds driven by changes in sea surface temperature owing to suppression of equatorial upwelling in the east Pacific) is not necessary(5) for the development of an El Nino. Thus it is unclear what remains constant through regimes and is crucial for producing the anomalies recognized as El Nino. Here we show that the subsurface process of discharging warm waters always begins in the boreal summer/autumn of the year before the event (up to 18 months before the peak) independent of regimes, identifying the discharge process as fundamental to the El Nino onset. It is therefore imperative that models capture this process accurately to further our theoretical understanding, improve forecasts and predict how the El Nino/Southern Oscillation may respond to climate change.

Item Type:	Journal Article
Publication:	NATURE CLIMATE CHANGE
Publisher:	NATURE PUBLISHING GROUP
Additional Information:	Copyright for this article belongs to NATURE PUBLISHING GROUP, ENGLAND
Department/Centre:	Division of Mechanical Sciences > Divecha Centre for Climate Change
Date Deposited:	22 Jan 2013 06:44
Last Modified:	22 Jan 2013 06:44
URI:	http://eprints.iisc.ac.in/id/eprint/45680

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