Importance of Late Fall ENSO Teleconnection in the Euro-Atlantic Sector

King, Martin P.; Bulić, Ivana Herceg; Bladé, Ileana; Garcı́a-Serrano, Javier; Keenlyside, Noel; Kucharski, Fred; Li, Camille; Sobolowski, Stefan

doi:10.1175/bams-d-17-0020.1

Cited by 58 publications

(69 citation statements)

References 34 publications

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“…Finally, there may be differences in ENSO tropospheric and stratospheric teleconnections between early and late winter. Moron and Gouirand (), King et al (), and Ayarzagüena, Inseon, et al, () suggest that there exists a significantly different teleconnection of ENSO to the Europe/North Atlantic sector in November‐December versus January‐March. Herceg‐Bulić et al () find that the January‐March ENSO response over Europe is maintained by both the stratosphere and extratropical Atlantic SSTs.…”

Section: Enso Teleconnections To the Stratospherementioning

confidence: 99%

The Teleconnection of El Niño Southern Oscillation to the Stratosphere

Domeisen

Garfinkel²,

Butler

2019

Reviews of Geophysics

316

284

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El Niño and La Niña events in the tropical Pacific have significant and disrupting impacts on the global atmospheric and oceanic circulation. El Niño Southern Oscillation (ENSO) impacts also extend above the troposphere, affecting the strength and variability of the stratospheric polar vortex in the high latitudes of both hemispheres, as well as the composition and circulation of the tropical stratosphere. El Niño events are associated with a warming and weakening of the polar vortex in the polar stratosphere of both hemispheres, while a cooling can be observed in the tropical lower stratosphere. These impacts are linked by a strengthened Brewer-Dobson circulation. Anomalous upward wave propagation is observed in the extratropics of both hemispheres. For La Niña, these anomalies are often opposite. The stratosphere in turn affects surface weather and climate over large areas of the globe. Since these surface impacts are long-lived, the changes in the stratosphere can lead to improved surface predictions on time scales of weeks to months. Over the past decade, our understanding of the mechanisms through which ENSO can drive impacts remote from the tropical Pacific has improved. This study reviews the possible mechanisms connecting ENSO to the stratosphere in the tropics and the extratropics of both hemispheres while also considering open questions, including nonlinearities in the teleconnections, the role of ENSO diversity, and the impacts of climate change and variability.Plain Language Summary El Niño and La Niña events, the irregular warming and cooling of the tropical Pacific that occurs every couple of years, have disrupting impacts spanning the entire world. These remote impacts, so-called "teleconnections", also reach the stratosphere, the layer of the atmosphere starting at around 10 km above the Earth's surface. El Niño leads to a warming of the stratosphere in both hemispheres, while the lower tropical stratosphere cools. These signatures are linked by a strengthened stratospheric circulation from the tropics to the polar regions. El Niño also leads to more frequent breakdowns of the stratospheric polar vortex, a band of strong eastward winds in the polar stratosphere. For La Niña, these effects tend to be opposite, though they are not always robust, suggesting nonlinear or nonstationary effects, long-term variability, and trends in the teleconnections. The observational data record is not yet long enough to make conclusions with certainty, and models that try to reproduce the teleconnections indicate that teleconnections might be more linear than the limited number of observations indicate. Further research will be needed to separate the El Niño and La Niña teleconnections from other effects and to determine to what extent nonlinearity and nonstationarity are indeed present.

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Section: Enso Teleconnections To the Stratospherementioning

confidence: 99%

The Teleconnection of El Niño Southern Oscillation to the Stratosphere

Domeisen

Garfinkel²,

Butler

2019

Reviews of Geophysics

316

284

View full text Add to dashboard Cite

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“…In January and February, a Rossby wave develops fully over the North Pacific and North America, while the signal over the North Atlantic-Europe region becomes weak and indistinct. When we perform the MCA on the individual months using reanalysis, for November the Z500 leading mode pattern is similar to the EA pattern in the North Atlantic, with weak amplitudes in the North Pacific, in agreement with King et al (2018). For December, anomalies in the extratropical Pacific strengthen and the EA weakens, and a k 5 3 wave pattern emerges.…”

Section: Conclusion and Discussionmentioning

confidence: 59%

“…The MCA Z500 pattern in this region is more related to the El Niño extratropical pattern, which has been suggested to be distinct from the PNA in both the spatial structure and probability distribution (Straus and Shukla 2002). King et al (2018) showed that the ENSO teleconnection pattern exhibits intraseasonal changes between November and the next February. In November, the teleconnection is strong over the North Atlantic and Europe, with the El Niño teleconnection resembling the positive east Atlantic (EA) teleconnection pattern.…”

Section: Conclusion and Discussionmentioning

confidence: 83%

Effect of the North Pacific Tropospheric Waveguide on the Fidelity of Model El Niño Teleconnections

Woollings

O’Reilly

et al. 2020

Journal of Climate

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In a free-running climate model, DJF tropical–extratropical teleconnections are assessed and compared to observed teleconnections in reanalysis data. From reanalysis, the leading mode of covariability between tropical outgoing longwave radiation (OLR) and Northern Hemisphere extratropical geopotential height (Z500) is identified using maximum covariance analysis (MCA). This mode relates closely to the El Niño pattern. The GCM captures the tropical OLR well but the associated extratropical Z500 less well. The GCM climatology has an equatorward shifted North Pacific jet bias. We examine whether the difference in the teleconnection pattern is related to the GCM’s jet bias. In both a ray-tracing analysis and a barotropic model, this jet bias is shown to affect the Rossby wave propagation from the tropical Pacific into the North Pacific. These idealized model results suggest qualitatively that the MCA difference is largely consistent with linear Rossby wave dynamics. While the basic state has a larger effect on the North Pacific MCA, a Rossby wave source (RWS) bias in the Caribbean has a larger effect on the North Atlantic MCA. The North Pacific jet bias is also proposed to affect the downstream propagation of waves from North America into the Caribbean, where it affects tropical RWS and the triggering of secondary waves into the North Atlantic. We propose that climatological biases in the tropics are one underlying cause of the jet bias. Our study may also help understand the results of other climate models with similar jet biases.

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“…; King et al . ; KNMI, ). It should be further noted that, while we only claim weak correlation between the pressure‐gradient forcing and the fog anomaly, the other studies also found only relatively weak correlations (∼0.4) between the synoptic indices and their relevant variables of interest.…”

Section: Discussionmentioning

confidence: 99%

“…; King et al . ). However, the extent to which these factors influence the occurrence of fog on interannual and spatial scales remains unclear.…”

Section: Introductionmentioning

confidence: 97%

Dutch fog: On the observed spatio‐temporal variability of fog in the Netherlands

Izett

Wiel

Baas

et al. 2019

Quart J Royal Meteoro Soc

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The Netherlands is characterized by highly variable land use within a small area, and a strong influence of the North Sea on national climate. Devoid of significant topography, it is an excellent location for assessing the relative influence of various factors on fog occurrence in the absence of terrain effects. Using observations from a dense network of weather stations throughout the country, the climatology of fog in the Netherlands is assessed over a period of 45 years. On a national scale, interannual variability is linked to changes in synoptic pressure‐gradient forcing. Within the country, a comprehensive in‐depth analysis of regional differences between fog occurrence is made, together with an assessment of local physical factors which could bias fog formation in one location over another. Regional variability is shown to be strongly related to the mesoscale influences of urbanization and the North Sea. In fact, some locations experience over twice as much fog as others. From this finding, a simple index is presented, which combines the water and urban fraction surrounding a station. This “Regionally Weighted Index” (RWI) is able to accurately sort the stations according to their relative fogginess. Its practical use is encouraged for assessing a given site's climatological favourability, even when in situ meteorological observations are unavailable.

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Importance of Late Fall ENSO Teleconnection in the Euro-Atlantic Sector

Cited by 58 publications

References 34 publications

The Teleconnection of El Niño Southern Oscillation to the Stratosphere

The Teleconnection of El Niño Southern Oscillation to the Stratosphere

Effect of the North Pacific Tropospheric Waveguide on the Fidelity of Model El Niño Teleconnections

Dutch fog: On the observed spatio‐temporal variability of fog in the Netherlands

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