Indices of El Niño Evolution

Trenberth, Kevin E.; Stepaniak, David P.

doi:10.1175/1520-0442(2001)014<1697:lioeno>2.0.co;2

Cited by 878 publications

(699 citation statements)

References 14 publications

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“…The MEI cannot differentiate between 'different flavours' of El Niño (Trenberth and Stepaniak, 2001), or weigh in on the debate whether there are fundamentally different so-called Eastern-Pacific versus Central-Pacific events (Kao and Yu, 2009). It was ironic to witness the very first El Niño after Rasmusson and Carpenter (1982) described the 'canonical sequence' of El Niño events as a westward propagating phenomenon from the eastern Pacific, to be the 1982-1983 'Super-El Niño' that propagated eastward from the Central Pacific.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

“…It was ironic to witness the very first El Niño after Rasmusson and Carpenter (1982) described the 'canonical sequence' of El Niño events as a westward propagating phenomenon from the eastern Pacific, to be the 1982-1983 'Super-El Niño' that propagated eastward from the Central Pacific. There were several more events of this type since then, most prominently the 1986-1988 and 1991-1995 events, leading some to proclaim that there had been a fundamental shift in behaviour (Trenberth and Stepaniak, 2001). For the newer record, we can confirm that central Pacific events tend to start later in the calendar year than eastern-Pacific events (Kao and Yu, 2009), but found that most events of either type end up becoming basin-wide nevertheless, rendering their distinction less meaningful once fully established.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

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

Wolter

Timlin

2011

Intl Journal of Climatology

970

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: Discussion and Concluding Remarksmentioning

confidence: 99%

Section: Discussion and Concluding Remarksmentioning

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

970

696

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“…The data base, spanning from January 1910 to December 2011 in monthly time steps, has a spatial resolution of 2 × 2º. We excluded iced-oceans by extracting data only from 70º S to 70º N. From the same website we downloaded the time series of the Atlantic Multidecadal Oscillation (AMO; Enfield et al, 2001), the Pacific Decadal Oscillation (PDO; Mantua et al, 1997), and the Trans Niño Index (TNI; Trenberth and Stepaniak, 2001), and plotted them with a five year moving average filter to explore similarities in the variability patterns.…”

Section: Methodsmentioning

confidence: 99%

Recent trends in sea surface temperature off Mexico

et al. 2013

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RESUMENLos cambios de temperatura promedio del océano a nivel global tienen el potencial de afectar negativamente los sistemas naturales y socioeconómicos actuales; sin embargo, los registros para proyectar las tendencias de cambio a nivel regional son escasos y, en algunos casos, contradictorios. En este estudio se analizan las señales de cambio de la temperatura superficial en mares mexicanos, y se comparan con otras regiones del planeta y con indicadores climáticos clave, tanto del Pacífico Norte como de la franja tropical en el Atlántico y el Pacífico. Se identificaron ocho regiones con diferente exposición a la variabilidad climática: en el Pacífico, la costa occidental de la península de Baja California no muestra una tendencia clara, el Golfo de California exhibe una tendencia modesta de enfriamiento durante los últimos 20 a 25 años, en la parte más oceánica del Pacífico mexicano se nota una tendencia intensa de enfriamiento, la región más tropical muestra una tendencia intensa de calentamiento, y entre ambas regiones se forma una banda de transición sin tendencia; en el Atlántico, la parte noreste del Golfo de México muestra una tendencia de enfriamiento, en tanto que la parte oeste, junto con el Caribe, se han estado calentando por lo menos durante los últimos 30 años. Se analizan las interacciones potenciales de estas tendencias con algunas pesquerías principales y la presencia de ecosistemas costeros sensibles. ABSTRACTChanges in global mean sea surface temperature may have potential negative implications for natural and socioeconomic systems; however, measurements to predict trends in different regions have been limited and sometimes contradictory. In this study, an assessment of sea surface temperature change signals in the seas off Mexico is presented and compared to other regions and the world ocean, and to selected basin scale climatic indices of the North Pacific, the Atlantic and the tropical Pacific variability. We identified eight regions with 538 S. E. Lluch-Cota et al. different exposure to climate variability: In the Pacific, the west coast of the Baja California peninsula with mostly no trend, the Gulf of California with a modest cooling trend during the last 20 to 25 years, the oceanic area with the most intense recent cooling trend, the southern part showing an intense warming trend, and a band of no trend setting the boundary between North-Pacific and tropical-Pacific variability patterns; in the Atlantic, the northeast Gulf of Mexico shows cooling, while the western Gulf of Mexico and the Caribbean have been warming for more than three decades. Potential interactions with fisheries and coastal sensitive ecosystems are discussed.

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“…The ±0.5°C threshold is consistent with the ONI. Following Trenberth (1997), a threshold sensitivity analysis was carried out for the ±0.4°C ENSO definition given by Trenberth (1997) and Trenberth and Stepaniak (2001) to allow event-capture discrepancies to be investigated.…”

Section: Oceanic Component Of Enso; El Niñomentioning

confidence: 99%

“…This was derived from the HadISST (Hadley Centre Sea Ice and Sea Surface Temperature) dataset using 1°× 1°l atitude/longitude grids with all area averages and interpolation computations calculated at full resolution (Trenberth and Stepaniak, 2001). The period of overlap between observational and reconstructed SSTs was analysed to assess the ability of the latter to serve as a reliable pre-instrumental surrogate, details of which are found in Section 3.1.…”

Section: Oceanic Component Of Enso; El Niñomentioning

confidence: 99%

Classification of synchronous oceanic and atmospheric El Niño-Southern Oscillation (ENSO) events for palaeoclimate reconstruction

Gergis

Fowler

2005

Int. J. Climatol.

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Since the mid-1970s, ENSO has changed in character to a predominance of El Niño conditions, the extreme phase of which appears coincidental with increases in global temperature records. Instrumental time series (<150 years) are too short to adequately address the significance of late twentieth-century ENSO variability, thus, multi-century palaeoclimate reconstructions derived from long proxy records are sought. Despite the global influence exerted by ENSO on society, limited consensus exists within the scientific community as to which index best defines the timing, duration and strength of events. Here we address issues associated with the complexity of ENSO characterisation by comparing the 'event capture' ability of two currently used indices of ENSO. It is suggested that the use of a sole ENSO index is undesirable as a given index is only indicative of one physical aspect of the phenomenon, and as such is unlikely to be representative of the wider interactions experienced in the coupled ocean-atmospheric system. In an attempt to describe more of the nature and evolution of ENSO events, the Coupled ENSO Index (CEI) classification scheme was devised to identify synchronous oceanic (Niño 3.4 SST) and atmospheric (Southern Oscillation Index) anomalies associated with ENSO for the instrumental period . The CEI is of practical relevance to the ENSO community as it provides an amplitude preserving instrumental baseline for the calibration of proxy records to reconstruct both components of the ENSO system. Analysis of the nature of instrumental ENSO events from the CEI suggests that the frequency and intensity of post-1970 ENSO events (when 50% of all extreme events identified occur) appears the most anomalous in the context of at least the past century. It is hoped that the CEI will facilitate palaeo-ENSO research to systematically resolve the long-term context of past ENSO behaviour to assess whether the apparently anomalous nature of late twentieth-century variability is unprecedented within existing palaeoclimate archives.

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Indices of El Niño Evolution

Cited by 878 publications

References 14 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)

Recent trends in sea surface temperature off Mexico

Classification of synchronous oceanic and atmospheric El Niño-Southern Oscillation (ENSO) events for palaeoclimate reconstruction

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