Stochastic theories for the irregularity of ENSO

Kleeman, Richard

doi:10.1098/rsta.2008.0048

Cited by 47 publications

(39 citation statements)

References 44 publications

(59 reference statements)

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“…On the other hand, the two shortest, 'aborted' La Niña events lasted only two sliding bimonthly seasons each (both in 1962), attesting to a wider range of duration for La Niña events than El Niño. It is beyond the scope of this paper to discuss the complicated reasons that determine the duration of ENSO events, but the reader is referred to Eccles and Tziperman (2004), Kleeman (2008), andMacMynowski andTziperman (2008) that explore both linear and nonlinear mechanisms for this at length. Returning to the issue of the longest-lasting La Niña events in the sense of Trenberth and Hoar (1997), it is perhaps noteworthy that one of the three longestlasting runs below the MEI.ext median was completed just in this millennium (1998-2002: 43 months), while the other two occurred about a century ago: 1891-1895 (45 months), and 1907-1911 (46 months).…”

Section: Spatial Features Of the Meiextmentioning

confidence: 99%

El Niño/Southern Oscillation behaviour since 1871 as diagnosed in an extended multivariate ENSO index (MEI.ext)

Wolter

Timlin

2011

Intl Journal of Climatology

920

696

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El Niño/Southern Oscillation (ENSO) remains the most important coupled ocean-atmosphere phenomenon to cause global climate variability on seasonal to interannual time scales. This paper addresses the need for a reliable ENSO index that allows for the historical definition of ENSO events in the instrumental record back to 1871. The Multivariate ENSO Index (MEI) was originally defined as the first seasonally varying principal component of six atmosphere-ocean (COADS) variable fields in the tropical Pacific basin. It provides for a more complete and flexible description of the ENSO phenomenon than single variable ENSO indices such as the SOI or Niño 3.4 SST. Here we describe our effort to boil the MEI concept down to its most essential components (based on SLP, SST) to enable historical analyses that more than double its period of record to 1871-2005. The new MEI.ext confirms that ENSO activity went through a lull in the earlyto mid-20th century, but was just about as prevalent one century ago as in recent decades. We diagnose strong relationships between peak amplitudes of ENSO events and their duration, as well as between their peak amplitudes and their spacing (periodicity). Our effort is designed to help with the assessment of ENSO conditions through as long a record as possible to be able to differentiate between 'natural' ENSO behaviour in all its rich facets, and the 'Brave New World' of this phenomenon under evolving GHG-related climate conditions. So far, none of the behaviour of recent ENSO events appears unprecedented, including duration, onset timing, and spacing in the last few decades compared to a full century before then.

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Section: Spatial Features Of the Meiextmentioning

confidence: 99%

El Niño/Southern Oscillation behaviour since 1871 as diagnosed in an extended multivariate ENSO index (MEI.ext)

Wolter

Timlin

2011

Intl Journal of Climatology

920

696

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“…Such models are part of a model hierarchy for ENSO that includes low-order deterministic and stochastic models (Thompson and Battisti 2001;Timmermann et al 2003;Kleeman 2008;Gehne et al 2014;Thual et al 2016), intermediate-complexity models (Zebiak and Cane 1987;Suarez and Schopf 1988;Jin and Neelin 1993;Kleeman et al 1999), and coupled climate models (Neelin et al 1994;Deser et al 2012;Choi et al 2013;Bellenger et al 2014). …”

Section: Introductionmentioning

confidence: 99%

Indo-Pacific Variability on Seasonal to Multidecadal Time Scales. Part I: Intrinsic SST Modes in Models and Observations

Sławińska

Giannakis

2017

J. Climate

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“…Meinen and McPhaden (2000) showed that a sufficiently high Pacific warm water volume (WWV; the volume of water warmer than 208C) is relevant for the occurrence of El Niño events because in order to warm the eastern Pacific Ocean (PO), sufficient heat should be present in the western PO, which is then discharged during El Niño. Also, small-scale processes can play a role in ENSO (Kleeman 2008), in particular intraseasonal spells of westerly winds (Keen 1982), such as those provided by the Madden-Julian oscillation (MJO) (Madden and Julian 1971;Zhang 2005). ''Bursts'' of westerly winds over the western PO generate equatorial Kelvin waves, which affect the thermocline in the eastern PO, favoring the development of an El Niño (Kessler et al 1995;McPhaden et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Coherent Tropical Indo-Pacific Interannual Climate Variability

et al. 2016

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A multichannel singular spectrum analysis (MSSA) applied simultaneously to tropical sea surface temperature (SST), zonal wind, and burstiness (zonal wind variability) reveals three significant oscillatory modes. They all show a strong ENSO signal in the eastern Pacific Ocean (PO) but also a substantial SST signal in the western Indian Ocean (IO). A correlation-based analysis shows that the western IO signal contains linearly independent information on ENSO. Of the three Indo-Pacific ENSO modes of the MSSA, one resembles a central Pacific (CP) El Niño, while the others represent eastern Pacific (EP) El Niños, which either start in the central Pacific and grow eastward (EPe) or start near Peru and grow westward (EPw). A composite analysis shows that EPw El Niños are preceded by cooling in the western IO about 15 months earlier. Two mechanisms are discussed by which the western IO might influence ENSO. In the atmospheric bridge mechanism, subsidence over the cool western IO in autumn (year 0) leads to enhanced convection above Indonesia, strengthening easterlies over the western PO, and the creation of a large warm water volume. This is essential for the creation of (EP) El Niños in the following spring-summer. In the state-dependent noise mechanism, a cool western IO favors a strong intraseasonal zonal wind variability over the western PO in early spring (year 1), which can partly be attributed to the Madden-Julian oscillation. This intraseasonal variability induces Kelvin waves, which in early spring lead to a strong warming of the eastern PO and can initiate EPw El Niños.

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Stochastic theories for the irregularity of ENSO

Cited by 47 publications

References 44 publications

El Niño/Southern Oscillation behaviour since 1871 as diagnosed in an extended multivariate ENSO index (MEI.ext)

El Niño/Southern Oscillation behaviour since 1871 as diagnosed in an extended multivariate ENSO index (MEI.ext)

Indo-Pacific Variability on Seasonal to Multidecadal Time Scales. Part I: Intrinsic SST Modes in Models and Observations

Coherent Tropical Indo-Pacific Interannual Climate Variability

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