Resampling of ENSO teleconnections: accounting for cold-season evolution reduces uncertainty in the North Atlantic

King, Martin P.; Li, Camille; Sobolowski, Stefan

doi:10.5194/wcd-2-759-2021

Cited by 8 publications

(14 citation statements)

References 40 publications

(71 reference statements)

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“…More generally, this study contributes to a larger body of literature arguing that seasonal‐mean analyses of teleconnections, and of stratosphere–troposphere coupling in particular, can blur over important details (Jiménez‐Esteve and Domeisen, 2018; Kretschmer et al ., 2018a; King et al ., 2021). While differences in the monthly surface response to SSWs were here demonstrated to be the result of the SSW definition, other teleconnections and their seasonal dependencies might give further insights into European climate variability.…”

Section: Discussionmentioning

confidence: 99%

“…For example, the influence of La Niña on the NAO is mostly observed during February but not during the other winter months (Jiménez‐Esteve and Domeisen, 2018). Similarly, the North Atlantic response to ENSO in late autumn was proposed to be different compared to mid‐winter (King et al ., 2021). Understanding how these other mechanisms are related to our findings and contribute to differences in the surface response to SSWs is important but is beyond the scope of the present study.…”

Section: Discussionmentioning

confidence: 99%

“…The purpose of this study is to investigate whether the timing of a SSW within the cold season (from December to March) plays a role in the surface response. Such differences have been documented for other drivers of European weather and climate, such as the El Niño Southern Oscillation (Jiménez‐Esteve and Domeisen, 2018; King et al ., 2021), but have as of yet not been documented for SSWs. While SSWs are linked to a range of extreme events in different regions (Domeisen and Butler, 2020), here, we focus on anomalous temperature and precipitation in Europe.…”

Section: Introductionmentioning

confidence: 99%

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The role of the timing of sudden stratospheric warmings for precipitation and temperature anomalies in Europe

Monnin

Kretschmer

Polichtchouk

2021

Intl Journal of Climatology

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The Northern Hemisphere stratospheric polar vortex (SPV), a band of fast westerly winds over the Pole extending from approximately 10 to 50 km altitude, is a key driver of European winter weather. Extremely weak polar vortex states, so called sudden stratospheric warmings (SSWs), are on average followed by dry and cold weather in Northern Europe, as well as wetter weather in Southern Europe. However, the surface response of SSWs varies greatly between events, and it is not well understood which factors modulate this difference. Here, we address the role of the timing of SSWs within the cold season (December–March) for the temperature and precipitation response in Europe. Given the limited sample size of SSWs in the observations, hindcasts of the seasonal forecasting model SEAS5 from the European Centre for Medium‐Range Weather Forecasts are analysed. First, we evaluate key characteristics of stratosphere–troposphere coupling in SEAS5 against reanalysis data and find them to be reasonably well captured by the model, justifying our approach. We then show that in SEAS5, early winter (December and January) SSWs are followed by more pronounced surface impacts compared to late winter (February and March) SSWs. For example, in Scotland, the low precipitation anomalies are roughly twice as severe after early winter SSWs than after late winter SSWs. The difference in the response cannot be explained by more downward propagating SSWs in early winter, or by different monthly precipitation climatologies. Instead, we demonstrate that the differences result from stronger SPV anomalies associated with early winter SSWs. This is a statistical artefact introduced through the commonly used SSW event definition, which involves an absolute threshold, and, therefore, leads to stronger SPV anomalies during early winter SSWs when the stratospheric mean state is stronger. Our study highlights the sensitivity of surface impacts to SSW event definition.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The role of the timing of sudden stratospheric warmings for precipitation and temperature anomalies in Europe

Monnin

Kretschmer

Polichtchouk

2021

Intl Journal of Climatology

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“…and high-latitude Eurasian snow cover (J. L. Cohen et al, 2012;Furtado et al, 2015;Orsolini & Kvamstø, 2009; may have significant influences on the climate over the downstream East Asia through inducing a distinct thermal and dynamical teleconnection. Most of these studies have focused on seasonal mean conditions, while more and more studies emphasized that the teleconnections on the monthly time scale are different to the seasonal mean (He & Wang, 2013;King et al, 2018King et al, , 2021.…”

mentioning

confidence: 99%

Atmospheric Contributions to the Reversal of Surface Temperature Anomalies Between Early and Late Winter Over Eurasia

Zhou

et al. 2022

Earth's Future

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Observations have shown subseasonal reversal of temperature anomalies between early and late winter over Eurasia, which is distinct from the seasonal mean condition. Based on the reanalysis data, the 1800‐year control simulation and the 40‐member ensemble simulations in 1920–2100 from the Community Earth System Model (CESM) Large Ensemble (CESM‐LE), this study reveals that the reversal of surface air temperature (SAT) anomalies between early and late winter is one of the dominant and intrinsic features of the Arctic‐Eurasian winter climate. Such a reversal is characterized by “colder Arctic, warmer Eurasia” in December (January–February) and “warmer Arctic, colder Eurasia” in January–February (December). Robust climate dynamic processes associated with the reversal of SAT anomalies, including subseasonal reversals of anomalies in the Ural blocking, midlatitude westerlies, and stratospheric polar vortex, are found in both reanalysis data and CESM simulations, indicating the important role of internal atmospheric variability. Further analysis reveals that the reversal of Ural blocking anomalies in late December can be a potential precursor for the reversal of SAT anomalies in late winter. The reversal of midlatitude westerly wind anomalies associated with the Ural blocking can affect upward propagation of planetary‐scale waves especially with wavenumber 1, subsequently promoting the contribution of stratospheric polar vortex to the reversal of SAT anomalies in late winter over the Arctic‐Eurasian regions. Such a troposphere‐stratosphere pathway triggered by the perturbation of tropospheric circulations is confirmed by the CESM‐LE simulations, and it may be useful for the prediction of subseasonal reversal of SAT anomalies.

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“…For consistency with the tropical teleconnections discussed in Sect. 4, which display a significant sub-seasonal variability (Ayarzagüena et al, 2018;King et al, 2021), we compute these covariances from bi-monthly mean anomalies in January and February (JF) over the 1981-2020 period. The same teleconnection patterns, computed from ERA5 data, are also shown for comparison.…”

Section: Atmospheric Mean State and Teleconnectionsmentioning

confidence: 99%

Multi-decadal pacemaker simulations with an intermediate-complexity climate model

Molteni,

Kucharski,

Farneti

2024

Weather Clim. Dynam.

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Abstract. In this paper, we first describe the main features of a new version of the International Centre for Theoretical Physics global atmospheric model (SPEEDY) with improved simulation of surface fluxes and the formulation of a three-layer thermodynamic ocean model (TOM3) suitable to explore the coupled extratropical response to tropical ocean variability. Then, we present results on the atmospheric model climatology, highlighting the impact of the modifications introduced in the model code, and show how important features of interdecadal and interannual variability are simulated in a “pacemaker” coupled ensemble of 70-year runs, where portions of the tropical Indo-Pacific are constrained to follow the observed variability. Despite the very basic representation of variations in greenhouse forcing and heat transport to the deep ocean (below the 300 m domain of the TOM3 model), the coupled ensemble reproduces the variations in surface temperature over land and sea with very good accuracy, confirming the role of the Indo-Pacific as a “pacemaker” for the natural fluctuations of global-mean surface temperatures found in earlier studies. Atmospheric zonal-mean temperature trends over 50 years are also realistically simulated in the extratropical lower troposphere and up to 100 hPa in the tropics. On the interannual scale, sea-surface temperature (SST) variability in sub-tropical and tropical regions not affected by SST relaxation is underestimated (mostly because of the absence of dynamically induced variability), while extratropical SST variability during the cold seasons is comparable to that observed. Atmospheric teleconnection patterns and their connections with SST are reproduced with high fidelity, although with local differences in the amplitude of regional features (such as a larger-than-observed response of extratropical SST to North Atlantic Oscillation variability). The SPEEDY-TOM3 model also reproduces the observed connection between averages of surface heat fluxes over the oceans and land surface air temperature in the wintertime northern extratropics. Overall, as in earlier versions of SPEEDY, the fidelity of the simulations (both in terms of climatological means and variability) is higher near the surface and in the lower troposphere, while the negative impacts of the coarse vertical resolution and simplified parameterizations are mostly felt in the stratosphere. However, the improved simulation of surface heat fluxes and their impact on extratropical SST variability in this model version (obtained at a very modest computational cost) make the SPEEDY-TOM3 model a suitable tool to investigate the coupled response of the extratropical circulation to interannual and inter-decadal changes of tropical SST in ensemble experiments.

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Resampling of ENSO teleconnections: accounting for cold-season evolution reduces uncertainty in the North Atlantic

Cited by 8 publications

References 40 publications

The role of the timing of sudden stratospheric warmings for precipitation and temperature anomalies in Europe

The role of the timing of sudden stratospheric warmings for precipitation and temperature anomalies in Europe

Atmospheric Contributions to the Reversal of Surface Temperature Anomalies Between Early and Late Winter Over Eurasia

Multi-decadal pacemaker simulations with an intermediate-complexity climate model

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