Trends of atmospheric circulation during singular hot days in Europe

Jézéquel, Aglaé; Cattiaux, Julien; Naveau, Philippe; Radanovics, Sabine; Ribes, Aurélien; Vautard, Robert; Vrac, Mathieu; Yiou, Pascal

doi:10.1088/1748-9326/aab5da

Cited by 30 publications

(40 citation statements)

References 52 publications

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“…7). These results are also broadly consistent with the fact that (Jézéquel et al 2018a) found negligible trends in single-day circulation analogue frequency over the observational record for two European heat events, while (Yiou et al 2017) found robust changes to the frequency of resampled 31-day analogue sequences related to the unusually wet January of 2014 over the Southern UK. While the differences are stark between Figs.…”

Section: Reconciling Differences Between Changes To the Frequency Of supporting

confidence: 85%

“…A warming world might influence how often weather patterns conducive to exceptionally hot weather will occur over Central Europe (Jézéquel et al 2018a;Woollings et al 2018), as well as how warm summertime temperature maxima will reach. However, our results show further work is needed to properly quantify the uncertainty of these changes, both to understand the evolution of changes in the past and as warming continues into the future.…”

Section: Discussionmentioning

confidence: 99%

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Circulation analogues and uncertainty in the time-evolution of extreme event probabilities: evidence from the 1947 Central European heatwave

et al. 2019

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The science of extreme event attribution has rapidly expanded in recent years, with numerous studies dedicated to determining whether and to what extent anthropogenic climate change has increased the likelihood of specific extreme weather events occurring. However, the majority of such studies have focussed on extreme events which have occurred in the recent past (usually within the past 10 years) while minimal research efforts have considered the multitude of high-impact extreme climatic events which occurred throughout the instrumental record. This study proposes a framework to quantify how the likelihood of witnessing meteorological characteristics reminiscent of the 1947 Central European heatwave have evolved over time. We specifically examine circulation analogues as a tool to understand the relative role of dynamical and thermodynamic contributions to changes in the probability of experiencing similar heatwave events. Using a reanalysis-based dataset, our results show changes in the frequency of 1947-like extreme heat throughout the twentieth century to be highly sensitive to methodological choices, particularly in the context of disaggregating dynamic and thermodynamic changes in the risk of extreme heat. Evidence also suggests clear decadal variability in the occurrence of circulation patterns conducive to the 1947 heatwaves. Finally, we discuss how to appropriately consider the time-evolution of attribution statements, as well as the broader limitations of employing circulation analogues as a method to interrogate the dynamical contribution to the probability ratio of an extreme event.

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Section: Reconciling Differences Between Changes To the Frequency Of supporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Circulation analogues and uncertainty in the time-evolution of extreme event probabilities: evidence from the 1947 Central European heatwave

et al. 2019

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“…They are defined as those days with root-mean-square error of the anomalous Z500 field over (30°W to 15°E, 30-55°N), with respect to the same field during the mentioned 47 days, below their 5th percentile (Jézéquel et al, 2018). For each day from the SSW onset until the end of March 2018 (+47 days after the 2018 SSW), we counted the number of good analogues found in the reanalysis period (excluding that winter).…”

Section: Resultsmentioning

confidence: 99%

“…For each day from the SSW onset until the end of March 2018 (+47 days after the 2018 SSW), we counted the number of good analogues found in the reanalysis period (excluding that winter). They are defined as those days with root-mean-square error of the anomalous Z500 field over (30°W to 15°E, 30-55°N), with respect to the same field during the mentioned 47 days, below their 5th percentile (Jézéquel et al, 2018). To identify a stratospheric influence, the search was separated into winter days after SSWs (with SSWs, from now on) and the remaining winter days of 1979-2017.…”

Section: Resultsmentioning

confidence: 99%

Stratospheric Connection to the Abrupt End of the 2016/2017 Iberian Drought

Ayarzagüena

Barriopedro

Garrido-Perez

et al. 2018

Geophysical Research Letters

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Southwestern Europe experienced extraordinary rainy and windy conditions in March 2018, leading to the end of the most severe drought since 1970 at continental scale. This anomalous weather was linked to a persistent negative North Atlantic Oscillation pattern. Two weeks earlier a sudden stratospheric warming (SSW) took place, preceded by the strongest planetary wave activity on record. In this study, we explore the connection between the SSW and the weather shift by employing a weather regime approach and flow analogues. The timing of the downward propagation of the stratospheric anomalies, the transition to and persistence of the negative North Atlantic Oscillation weather regime, and the sudden precipitation increase are all consistent with the typical tropospheric state after SSWs. Our results evidence a significant role of the 2018 SSW in the record‐breaking precipitation event.

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“…We determine the temperature distribution conditional to atmospheric patterns that are similar to 2018 changes with time. Following the procedure of Jézéquel et al (2018b), we computed analogs of geopotential height at 500 mb (Z500) over a zone covering Scandinavia (rectangle in Fig. 1c), which optimizes the temperature/circulation correspondence.…”

Section: Conditional Attributionmentioning

confidence: 99%