Mechanisms linking multi-year La Niña with preceding strong El Niño

Iwakiri, Tomoki

doi:10.1038/s41598-021-96056-6

Cited by 41 publications

(44 citation statements)

References 54 publications

(67 reference statements)

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“…Moreover, the PC1 also shows two persistent excess rainfall events: a first event between 1998 and 2000 and a second event between 2010 and 2012, which coincide with the multiyear La Niña events discussed by Iwakiri and Watanabe [18] and Lopes et al [7]. An important feature of these events is that they were immediately preceded by El Niño events-in this case, the 1997-1998 and 2009-2010 periods, respectively, consistent with [18,75,76]. These events are reflected in the rainfall deficits in the SRB presented in Figure 3c.…”

Section: Standardized Precipitation Indexsupporting

confidence: 73%

“…In the last forty years, the El Niño (La Niña) events recorded during 1997-1998 and 2015-2016 (1998-2000 and 2010-2012) stand out as the strongest events, with significant negative consequences for the country [6,9,11,[15][16][17], mainly during La Niña events, which were of longer duration than El Niño events. According to Iwakiri et al [18], this behavior is due to the strong transition asymmetry of ENSO, whereby El Niño concludes quickly, whereas some La Niña events often last more than two years and are defined as multiyear events [7,18,19]. The persistence of multiyear El Niño and La Niña events exacerbate the induced climate impacts, generating persistent floods and droughts worldwide [9,[20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

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Multiscale Interactions of Climate Variability and Rainfall in the Sogamoso River Basin: Implications for the 1998–2000 and 2010–2012 Multiyear La Niña Events

Cerón

Díaz

Escobar-Carbonari

et al. 2022

Water

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In this research, we explored rainfall variability in the Sogamoso River Basin (SRB), its relationship with multiple scales of variability associated with El Niño–Southern Oscillation (ENSO), and the implications for rainfall prolongation during multiyear La Niña events. First, we examined time-frequency rainfall variations in the SRB based on the standardized precipitation index (SPI) from 1982 to 2019, using wavelet transform and principal component analysis (PCA). In addition, we applied wavelet analysis to investigate the links at different time scales between ENSO and the main mode of rainfall variability in the SRB. Finally, we explored the role that each scale of variability played in the prolongation and intensity of rainfall in the SRB during the 1998–2000 and 2010–2012 multiyear La Niña events. The results of the wavelet analyses revealed significant ENSO relationships affecting SRB rainfall at three different scales: quasi-biennial (2–3-years) between 1994 and 2002, as well as from 2008 to 2015; interannual (5–7 years) from 1995 to 2011; and quasi-decadal (9–12 years) from 1994 to 2012. This indicates that multiyear events are a consequence of the interaction of several scales of variability rather than a unique scale. During the 1998–2000 event, El Niño conditions were observed during the first half of 1998; subsequently, a cooling of the central and eastern tropical Pacific (western tropical Pacific) on the quasi-biennial (interannual) scale was observed during 1999; in 2000, only La Niña conditions were observed on the interannual scale. Therefore, during this event, the quasi-biennial (interannual) scale promoted wet conditions in the Caribbean, the Andes, and the Colombian Pacific from June–August (JJA) 1998 to JJA 1999 (during 1999–2000). During the 2010–2012 La Niña event, the interbasin sea surface temperature gradient between the tropical Pacific and tropical North Atlantic contributed to strengthening (weakening) of the Choco jet (Caribbean low-level jet) on the quasi-biennial scale during 2010, and the interannual scale prolonged its intensification (weakening) during 2011–2012, acting to extend the rainy periods over most of the Colombian territory. Variations on quasi-decadal scales were modulated by the Pacific decadal oscillation (PDO), resulting in a further intensification of the 2010–2012 La Niña event, which developed under conditions of the cold PDO (CPDO) phase, whereas the 1998–2000 La Niña occurred during the transition from warm (WPDO, 1977–1998) to cold (CPDO, 2001–2015) conditions. These results indicate that the interaction of quasi-biennial to quasi-decadal scales of variability could play a differential role in the configuration and prolongation of rainfall events in the SRB.

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Section: Standardized Precipitation Indexsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Multiscale Interactions of Climate Variability and Rainfall in the Sogamoso River Basin: Implications for the 1998–2000 and 2010–2012 Multiyear La Niña Events

Cerón

Díaz

Escobar-Carbonari

et al. 2022

Water

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“…The mean velocity‐weighted temperature over the Ekman layer,

T_{E}

, is calculated as follows:

T_{E} = \sum v_{n} (z) T (x, y, z),

v_{n} \propto e^{z / δ} \sin (\frac{- z}{δ} + \frac{π}{4}),

where

v_{n}

is the normalized velocity weight as a function of the ocean depth z . The Ekman layer depth,

δ

, is assumed to be constant at 70 m and not sensitive when 50 and 100 m are selected (Figure S3 in Supporting Information , Iwakiri & Watanabe, 2021). The contribution from the GHT is simply defined by the difference between the recharge rate and the EHT.…”

Section: Methods Of Analysismentioning

confidence: 99%

“…Indeed, McGregor et al (2013McGregor et al ( , 2014McGregor et al ( , 2016 showed that the Ekman-induced meridional surface transport is an important factor for ENSO phase transition in ocean general circulation model experiments. In addition, Iwakiri and Watanabe (2021) revealed that anomalous Ekman transport is crucial for linking strong El Niño with a subsequent 2-year persistent La Niña.…”

mentioning

confidence: 99%

Contribution of Ekman Transport to the ENSO Periodicity Estimated With an Extended Wyrtki Index

Iwakiri

2021

Geophysical Research Letters

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It is well known that El Niño-Southern Oscillation (ENSO) is represented by anomalous sea surface temperature (SST) in the eastern equatorial Pacific, which is positive in El Niño and negative in La Niña. Its oscillatory nature is an intrinsic feature of ENSO, which indicates a periodicity of 3-8 years in the observational record. Bjerknes (1969) first discovered the oscillatory property of ENSO and argued that the SST anomaly grows by air-sea coupled instability. Wyrtki (1985) found a redistribution of ocean heat content (OHC) in the equatorial Pacific between the equatorial band and the off-equator, which is now recognized as a process leading to the ENSO phase change.Based on these findings, Jin (1996, 1997a, 1997b) constructed a recharge oscillator (RO) paradigm, consisting of a two-dimensional system and explicitly representing the periodic feature of ENSO. The RO equations are expressed as follows:where T and h represent the SST anomaly in the eastern equatorial Pacific and the OHC anomaly averaged in the equatorial Pacific, respectively. The parameter R crudely represents the ENSO growth rate, and  E is the damping rate for the OHC. 1 E F and 2 E F are the phase transition rates for the SST and OHC, respectively.

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“…The composite multi-year La Niña is preceded by SSTAs characteristic of a strong El Niño that are absent from the single-year composite La Niña (cf., Figure 1a and Figure S1a in Supporting Information S1). Several previous studies have emphasized this pre-onset strong El Niño condition to explain the generation of multi-year La Niña events (Iwakiri & Watanabe, 2021;Larson & Pegion, 2020).…”

Section: Ssta Characteristics During Single-and Multi-year La Niñasmentioning

confidence: 96%

A Shifting Tripolar Pattern of Antarctic Sea Ice Concentration Anomalies During Multi‐Year La Niña Events

Zhu

2022

Geophysical Research Letters

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A 2,200‐year CESM1 pre‐industrial simulation is used to contrast Antarctic sea ice concentration (SIC) variations between the first and second austral winters of multi‐year La Niñas. The typical SIC anomaly pattern induced by single‐year La Niñas appears only during the second austral winter of multi‐year La Niñas. A similar pattern, but zonally shifted compared to the typical one, is found during the first winter and exhibits a tripolar pattern with anomaly centers over the Ross, Amundsen‐Bellingshausen, and Weddell Seas. The shift is a result of the pre‐onset conditions associated with multi‐year La Niñas that excites unique atmospheric circulation modes during the first winter. The distinct zonally‐shifted SIC anomaly pattern is observed in four of the six multi‐year La Niña events during the period 1979–2020. These results suggest that it is helpful to separate La Niñas into single and multi‐year events to better understand the La Niña impacts on Antarctic climate.

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Mechanisms linking multi-year La Niña with preceding strong El Niño

Cited by 41 publications

References 54 publications

Multiscale Interactions of Climate Variability and Rainfall in the Sogamoso River Basin: Implications for the 1998–2000 and 2010–2012 Multiyear La Niña Events

Multiscale Interactions of Climate Variability and Rainfall in the Sogamoso River Basin: Implications for the 1998–2000 and 2010–2012 Multiyear La Niña Events

Contribution of Ekman Transport to the ENSO Periodicity Estimated With an Extended Wyrtki Index

A Shifting Tripolar Pattern of Antarctic Sea Ice Concentration Anomalies During Multi‐Year La Niña Events

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