European Extremely Research Articles

Forecasting atmospheric persistence and implications for the predictability of temperature and temperature extremes

AbstractExtreme temperatures can cause severe disruptions to society, from negative health consequences to infrastructure damage. Accurate and timely weather forecasts contribute to minimising these detrimental effects, by supporting early‐warning systems. In this context, information on the expected performance of the forecasts is valuable. Here, we investigate whether there is a relationship between the persistence of atmospheric circulation patterns in the Euro‐Atlantic sector and forecast skill for temperatures and temperature extremes in Europe. We first apply an objective method to compute the persistence of large‐scale atmospheric patterns in European Centre for Medium‐Range Weather Forecasts (ECMWF) subseasonal retrospective forecasts. We find that the forecasts successfully predict atmospheric persistence up to time‐scales of approximately two weeks. We next investigate the relationship between the persistence of an atmospheric state and the practical predictability of temperature in terms of the error in surface temperature forecasts. The relationship between the two varies depending on season and location. Nonetheless, in a number of cases atmospheric persistence provides potentially valuable information on the practical predictability of temperature. We specifically highlight the cases of wintertime temperature forecasts up to three weeks lead time and wintertime cold spells up to roughly two weeks lead time.

From history to modern period: Jet stream drives European climatic and agricultural extremes

From history to modern period: Jet stream drives European climatic and agricultural extremes

Artificial intelligence reveals past climate extremes by reconstructing historical records

The understanding of recent climate extremes and the characterization of climate risk require examining these extremes within a historical context. However, the existing datasets of observed extremes generally exhibit spatial gaps and inaccuracies due to inadequate spatial extrapolation. This problem arises from traditional statistical methods used to account for the lack of measurements, particularly prevalent before the mid-20th century. In this work, we use artificial intelligence to reconstruct observations of European climate extremes (warm and cold days and nights) by leveraging Earth system model data from CMIP6 through transfer learning. Our method surpasses conventional statistical techniques and diffusion models, showcasing its ability to reconstruct past extreme events and reveal spatial trends across an extensive time span (1901-2018) that is not covered by most reanalysis datasets. Providing our dataset to the climate community will improve the characterization of climate extremes, resulting in better risk management and policies.

Ingot-like class of wavefront sensors for laser guide stars

Context. Full sky coverage adaptive optics (AO) on extremely large telescopes requires the adoption of several laser guide stars as references. With such large apertures, the apparent elongation of the beacons is absolutely significant. With a few exceptions, wavefront sensors (WFSs) designed for natural guide stars can be adapted and used in suboptimal mode in this context. Aims. We analyse and describe the geometrical properties of a class of WFSs that are specifically designed to deal with laser guide stars propagated from a location in the immediate vicinity of the telescope aperture. Methods. We describe, in three dimensions, the loci where the light of the laser guide stars would focus in the focal volume located behind the focal plane where astronomical objects are reimaged. We also describe the properties of several types of optomechanical devices that act as perturbers for this new class of pupil plane sensors, through refraction and reflections. We refer to these as ingot WFSs. Results. We provide the recipes both for the most reasonably complex version of these WFSs, with six pupils and, for the simplest one, only three pupils. Both of them are referred to on the basis of the European Extremely Large Telescope (ELT) case. We outlined elements that are meant to give a qualitative idea of how the sensitivity of this new class of sensors compares to conventional ones. Conclusions. We present a new class of WFSs, based on an extension to the case of elongated sources at a finite distance of the pyramid WFS. We point out which advantages of the pyramid can be retained and how it may be adopted to optimize the sensing procedure.

The linkage between autumn Barents-Kara sea ice and European cold winter extremes

While the Arctic's accelerated warming and sea ice decline have been associated with Eurasian cooling, debates persist between those attributing this to sea ice retreat and those to internal variability. Our study examines the association between autumn sea ice variability over the Barents-Kara Seas and extreme cold winters in Europe. Using the observational data and composite analysis, we explore the interannual variability and the potential linkage between sea ice and atmospheric circulation patterns. It reveals a correlation with shifts toward a negative phase of North Atlantic Oscillation and more frequent episodes of the atmospheric blocking over Greenland and the North Atlantic. Furthermore, the negative phase of the North Atlantic Oscillation and enhanced blocking are closely related and mutually reinforcing, shaping the spatial distribution of cold anomalies over much of the European continent. Our results suggest a link between the unusual decrease in Barents-Kara Sea ice during autumn and the occurrence of intense European weather extremes in subsequent winter months, emphasizing the need for delving deeper into this relationship on monthly time scales to enhance our predictive capabilities for midlatitude extreme events.

Jet Configurations Leading to Extreme Winter Temperatures Over Europe

AbstractThe North Atlantic eddy‐driven jet (EDJ) is the main driver of winter weather in Europe and has often been described by its latitude or strength. Here, we show that the influence of the EDJ on European winter temperature extremes can be better characterized by a multiparametric perspective that accounts for additional aspects of the EDJ structure (tilt, zonal elongation, etc.). We identify four regions where extreme temperatures are distinctly associated with the EDJ: Scandinavia, Central Europe, Eastern Europe, and Western Mediterranean (WMED). Overall, the anomalous horizontal advection induced by blockings during cold spells and enhanced westerlies during warm events is the main mechanism leading to extreme event occurrence. However, diabatic processes play an important role in WMED region. Both processes generate asymmetric effects in minimum and maximum temperatures contributing to higher intensities of cold than warm events. These extreme events are associated with different EDJ configurations, which typically involve perturbed EDJs during cold spells and strong tilted EDJs during warm events, but with important variations depending on the region. In almost every region, the combined effects of more than two EDJ parameters yield significant increases in the probability of cold and warm events, suggesting an oversimplification of traditional approaches based on a single EDJ parameter. We show, using logistic regression models, that, although important, latitude and intensity are often unable to discriminate unequivocally the region of extreme event occurrence, and in some regions, they do not drive the largest changes in the odds of extremes.

Modulation of North Atlantic extratropical cyclones and extreme weather in Europe during North American cold spells

Recent research has established a statistical link between North American cold spells (CS) and concurrent wet or windy extremes in Europe. Here, we investigate whether such a link can be related to changes in the characteristics of North Atlantic extratropical cyclones (hereafter cyclones). Despite large regions of anomalous baroclinicity during periods of North American CS, the number of cyclones across the North Atlantic as a whole is not significantly above climatology. However, we observe rates of explosive cyclogenesis significantly above climatology. We further find that CS over different North American regions are associated with large-scale atmospheric configurations displaying a strenghtened jet stream in the vicinity of the CS and different upper-level wind anomalies in the East Atlantic. These, in turn, modulate the regional distributions and characteristics of cyclones in the North Atlantic and Europe. We compute a fixed-radius cyclone footprint which we use to associate extreme precipitation and wind occurrences to individual cyclones. For eastern Canada CS, the North Atlantic jet extends over Northern Europe, resulting in a heightened numbers of cyclones for the British Isles and Scandinavia, while France, the British Isles, Northern Europe and Scandinavia all experience more intense cyclones. The British Isles consistently experience wind extremes associated with cyclones during east Canada CS. For central Canada CS, the jet is displaced poleward and only partly extends over Europe, resulting in an above average cyclone density in the eastern Atlantic and a higher number of cyclones affecting Iberia only. Iberia consistently experiences precipitation extremes associated with the cyclones during central Canada CS. For eastern United States CS, the jet is displaced equatorward and extends over Southern Europe, with a significantly heightened number of cyclones affecting Iberia and France. Iberia experiences wind extremes associated with the cyclones during eastern United States CS. Our results provide a dynamical explanation for previous statistical findings on the concurrence of North American CS and wet or windy extremes over Europe.

Optique adaptative : correction des effets de la turbulence atmosphérique sur les images astronomiques

Today, adaptive optics (AO) is installed on all very large astronomical telescopes. It allows to overcome the limitation in angular resolution imposed on large ground-based telescopes by the atmospheric turbulence perturbations. This review paper presents the state of the art of the field for astronomical applications. It gives the principles of AO and describes its main components which are the deformable mirrors, the wavefront sensors and the control algorithms. The paper also presents the main recent achievements and ongoing projects. First, for the direct imaging of extra-solar planets by extreme AO and coronography, taking as example the SPHERE instrument. Then to solve the problem of the very limited sky coverage by using laser guide star and to extend the AO correction beyond the isoplanatic patch. Thus, the various laser-assisted tomographic AO concepts are presented with examples of each realization as for the laser tomography AO, the multi-conjugate AO and the multi-object AO. Finally, the challenges of the new generation of giant telescopes are discussed at the end of the paper with a particular focus on the European Extremely Large Telescope (ELT) project.

Changes in European fire weather extremes and related atmospheric drivers

Recent destructive fire seasons around the world have increased concern that climate change is escalating the frequency, intensity, and extent of wildfires. While the contributions of individual factors can be debated, the scientific literature concludes that fire weather is one prominent driver of fire activity. Our analysis of the relationship between fire weather extremes and burned area in Europe revealed that the number of extreme fire weather days per year correlates positively with the annual burned area over most of the study domain. The evidence presented in our study strongly suggests that fire weather extremes in Europe have become more frequent in recent decades while affecting increasingly larger areas and occurring earlier and later in the fire season. Increases in fire weather extremes occurred abruptly in several parts of Europe, as evidenced by the detection of statistically significant change-points in the time series of the annual extreme fire weather days. Our analysis revealed that, at the regional scale, significant change-points occurred around the late 1990s and mid-2000s in the Mediterranean, marking an abrupt rise in the median of extreme fire weather days per year. We found that high-latitude blocking and sub-tropical ridging drive fire weather extremes in northern and southern Europe, respectively. The results of our study suggest that fire weather extremes are today more likely to occur than in the past, and the increasing occurrence of extreme fire weather could lead to rapidly reaching adaptation limits, thereby reversing currently stagnating or even declining trends reported for fire activity in Europe. Corresponding with extreme fire weather years reported here, recent destructive fire seasons exemplify the limits of fire suppression and the need to adapt to the reality of more frequent extreme fire weather.

Christian Extremism in Europe and its Impact on Technological Advancement

Europe has been a cradle of technological innovation for centuries. However, in recent times, the continent has witnessed the rise of Christian extremism that poses challenges to the progress of technology. This article explores the phenomenon of Christian extremism in Europe and its implications for technological development. It delves into the reasons behind this extremism, its impact on innovation, and possible strategies to address the issue.

Teledyne imaging sensors' recent contributions to astronomy, earth science, and planetary science

AbstractTeledyne Imaging Sensors (TIS) is the leading supplier of infrared focal plane arrays (FPAs) to astronomy and TIS plays a strong role in providing image sensors for Earth and Planetary Science. This article starts with a brief introduction to TIS' technologies and image sensor products. We then present some of TIS' deliveries to space missions and ground‐based telescopes. The space missions include ESA's Euclid Dark Universe mission and several NASA missions (James Webb Space Telescope, Roman Space Telescope, SPHEREx, EMIT). TIS continues to serve ground‐based astronomy by providing the H2RG and the world's largest high‐performance infrared astronomy FPA, the H4RG‐15, to several ground‐based observatories. Active programs will be described. Ongoing work includes NASA's NEO Surveyor asteroid surveillance mission, ESA's Ariel exo‐planet spectroscopy mission, and deliveries to the European Southern Observatory's Extremely Large Telescope.

The New Max Planck Institute Grand Ensemble With CMIP6 Forcing and High‐Frequency Model Output

AbstractSingle‐model initial‐condition large ensembles are powerful tools to quantify the forced response, internal climate variability, and their evolution under global warming. Here, we present the CMIP6 version of the Max Planck Institute Grand Ensemble (MPI‐GE CMIP6) with currently 30 realizations for the historical period and five emission scenarios. The power of MPI‐GE CMIP6 goes beyond its predecessor ensemble MPI‐GE by providing high‐frequency output, the full range of emission scenarios including the highly policy‐relevant low emission scenarios SSP1‐1.9 and SSP1‐2.6, and the opportunity to compare the ensemble to complementary high‐resolution simulations. First, we describe MPI‐GE CMIP6, evaluate it with observations and reanalyzes and compare it to MPI‐GE. Then, we demonstrate with six application examples how to use the power of the ensemble to better quantify and understand present and future climate extremes, to inform about uncertainty in approaching Paris Agreement global warming limits, and to combine large ensembles and artificial intelligence. For instance, MPI‐GE CMIP6 allows us to show that the recently observed Siberian and Pacific North American heatwaves would only avoid reaching 1–2 years return periods in 2071–2100 with low emission scenarios, that recently observed European precipitation extremes are captured only by complementary high‐resolution simulations, and that 3‐hourly output projects a decreasing activity of storms in mid‐latitude oceans. Further, the ensemble is ideal for estimates of probabilities of crossing global warming limits and the irreducible uncertainty introduced by internal variability, and is sufficiently large to be used for infilling surface temperature observations with artificial intelligence.

폭력적 극단주의 예방을 위한 교육프로그램 운영 방안에 관한 연구

Day after day, violent incidents by extremists continue to occur in the global village. Concerns about far-right terrorism or violent far-right extremism are rising in Europe as well as the United States, and these countries are nervous about the spread of far-right extremism or far-right terrorism that is unusually expanding. Recently, violent protests occurred in France because of the police's excessive suppression of second-generation immigrants, and in the Netherlands, a coalition government collapsed over the demand for refugees and migrants. The recent spread of violent far-right extremism in Europe appears to be closely related to the rapid influx of refugees into Europe since 2015.
 In this situation, in order to prevent the spread of violent extremism, it is persuasive to recognize that it is a social problem rather than the existing state-centered response, and to find a solution through integrated cooperative governance of the government, businesses, schools, and civic groups. In Korea, too, there are many vulnerable groups who are complaining of suffering in the shadow of economic growth and national development. While being discriminated against and alienated from society, they have dissatisfaction with the country, and teenagers who are not adapted to school are directly affected by the online community.
 Therefore, in this study, the concept of violent extremism is introduced, the factors and paths leading to violent extremism are examined, and measures for prevention are presented. First, we selected the vulnerable class who are most likely to be inclined to violent extremism in Korea and key stakeholders who are in a position to control and manage them. In order to operate a violent extremism prevention education program targeting them, it is important to understand the characteristics of the local community and active participation of various stakeholders, and differentiated and customized education for each vulnerable group is necessary. In addition, periodic evaluation and monitoring, budget and manpower security are important considerations.
 This study presents a customized education program targeting the vulnerable and key stakeholders. In the prevention education program, the contents of education for the selected vulnerable class and key stakeholders and the criteria for selecting instructors were presented. In addition, in order to continuously operate these programs, it was suggested that a feedback system to evaluate and improve their effectiveness should be established. Despite some limitations, this study is meaningful in that it has presented the most specific implementation plan among the papers in related fields published so far, and additional follow-up research will contribute to the prevention of violent extremism and the safety of the community.

Proscribing Right-Wing Extremist Organizations in Europe: Variations, Trends, and Prospects

ABSTRACT Among the legal instruments that address organized right-wing extremism in Europe, proscription is one of the most severe. Yet there is scant comparative work on where, how frequently, and against which right-wing extremist organization proscriptions have been applied. This article presents a new dataset on Proscribed Right-wing Extremist Organizations (PREOs) in Europe. A typology of countries’ proscriptive regimes illuminates how proscription by executive decrees is more frequent than proscription by judicial ruling, and how proscription by executive decrees appears to be more responsive to high-profile incidents of extremist violence. We complement this descriptive overview with a close investigation of patterns in Germany, the state that has most frequently used proscription against right-wing extremist organizations. Furthermore, the article presents paired case studies of the proscriptions of Blood & Honour in Germany (by executive decree) and the Nordic Resistance Movement in Finland (by judicial ruling), which point to the causal factors underlying proscription of right-wing extremist organizations.

The link between European warm-temperature extremes and atmospheric persistence

Abstract. We investigate the link between warm-temperature extremes in Europe and the persistence of large-scale atmospheric-circulation patterns for both winter and summer, along with some possible physical mechanisms connecting the two. We assess atmospheric persistence, leveraging concepts from dynamical systems theory, and reconcile this approach with the more conventional meteorological views of persistence. We find that wintertime warm spells are partly associated with persistent zonal advection at the surface level but display no statistically significant persistence anomaly in the mid-troposphere. For summertime heatwaves, we find a weak yet significant link to anomalously persistent circulation patterns in the mid-troposphere, while there are few significant persistence anomalies of the surface circulation pattern. We further find no evidence of a strong warm-temperature advection signal. This suggests that other radiative and dynamical processes, for example sensible heating and adiabatic warming, as well as local effects, could play a more important role than large-scale warm-temperature advection for these events. We thus argue that persistent atmospheric configurations are not a necessary requirement for warm-temperature extremes and that the results depend to a considerable extent on region and tropospheric level.

On the linkage between future Arctic sea ice retreat, Euro-Atlantic circulation regimes and temperature extremes over Europe

Abstract. The question to what extent Arctic sea ice loss is able to affect atmospheric dynamics and climate extremes over mid-latitudes still remains a highly debated topic. In this study we investigate model experiments from the Polar Amplification Model Intercomparison Project (PAMIP) and compare experiments with future sea ice loss prescribed over the entire Arctic, as well as only locally over the Barents and Kara seas, with a present-day reference experiment. The first step is to perform a regime analysis and analyze the change in occurrence frequencies of five computed Euro-Atlantic winter circulation regimes. Forced by future Arctic sea ice conditions, most models show more frequent occurrences of a Scandinavian blocking pattern in at least 1 winter month, whereas there is an overall disagreement between individual models on the sign of frequency changes of two regimes that, respectively, resemble the negative and positive phase of the North Atlantic Oscillation. Focusing on the ECHAM6 PAMIP experiments, we subsequently employ a framework of conditional extreme-event attribution. It demonstrates how detected regime frequency changes can be used to decompose sea-ice-induced frequency changes of European temperature extremes into two different contributions: one “changed-regime” term that is related to dynamical changes in regime occurrence frequencies and another more thermodynamically motivated “fixed-regime” contribution that is related to increased surface temperatures during a specific circulation regime. We show how the overall fixed-regime warming effect and also an increased Scandinavian blocking pattern frequency under future sea ice reductions can equally contribute to and shape the overall response signal of European cold extremes in midwinter. We also demonstrate how a decreased occurrence frequency of an anticyclonic regime over the eastern Atlantic dynamically counteracts the fixed-regime warming response and results in no significant changes in overall January warm-extreme occurrences. However, when compared to other characteristics of future climate change, such as the thermodynamical impact of globally increased sea surface temperatures, the effects of Arctic sea ice loss on European temperature extremes are of secondary relevance.

Juxtaposing violent extremism and critical radicalism in Europe: the role of reflexive awareness in pursuit of religious purity and cultural essence

ABSTRACT Employing an approach that focuses on three goals of ideology-making (i.e. resolving grievances, seeking status, socialization), this study explores the reflexive boundaries between (1) 68 individual representations of violent ‘Jihadi’ and ‘right-wing’ extremism in Europe, and (2) 130 young adult European citizens who pursue religious purity or cultural essence. Having identified the latter as a pool of ‘critical radicalism’ in the current political context, the study juxtaposes violent and non-violent radicalizations by challenging two interrelated assumptions. The first is the sameness assumption: those who use a similar repertoire are unified by their similarity. The second is the continuum assumption: radicalism will eventually lead to violence, given that ‘radicalization’ discursively implies a shift towards promoting or carrying out violent behaviour. Drawing on comparisons between interview and media narratives, I argue that violent extremism and critical radicalism part ways while developing reflective methods to evaluate grievances, reclaim agency in response to status losses, and align social bonds with the ideology. The conceptual divergence indicates several fault lines between ideological simplicity and completeness and relates to individuals’ self-awareness in (re)making the ideology rather than a given ideology. This concluding remark has implications for the value of reflexive awareness in democracies.

The potential of an increased deciduous forest fraction to mitigate the effects of heat extremes in Europe

Abstract. Deciduous forests are characterized by a higher albedo, a reduced stomatal resistance, and a deeper root system in comparison to coniferous forests. As a consequence, less solar radiation is absorbed and evapotranspiration is potentially increased, making an increase in the deciduous forest fraction a potentially promising measure to mitigate the burdens of heat extremes for humans and nature. We analyze this potential by means of an idealized 30-year-long regional climate model (RCM) experiment, in which all coniferous forests in Europe are replaced by deciduous forests and compared to a simulation using the actual forest composition. Results show that an increase in the deciduous forest fraction reduces the heat intensity during heat periods in most regions of Europe. During heat periods, there is a slight reduction in the mean daily maximum 2 m temperatures simulated of about 0.2 K locally and 0.1 K non-locally. Regions with a high cooling potential are southwestern France and northern Turkey, where heat period intensities are reduced by up to 1 K. Warming effects are simulated in Scandinavia and eastern Europe. Although the cooling effect on heat period intensities is statistically significant over large parts of Europe, the magnitude of the temperature reduction is small. Consequently, an increase in the deciduous forest fraction only has a limited potential to reduce heat period intensities in Europe and can therefore only be considered as a supporting mitigation measure to complement more effective mitigation strategies.

Spatially resolved mock observations of stellar kinematics: full radiative transfer treatment of simulated galaxies

ABSTRACT We present a framework to build realistic mock spectroscopic observations for state-of-the-art hydrodynamical simulations, using high spectral resolution stellar population models and full radiative transfer treatment with skirt. As a first application, we generate stellar continuum mock observations for the Auriga cosmological zoom simulations emulating integral-field observations from the Sydney–AOO Multi-object Integral Field Spectrograph (SAMI) Galaxy Survey. We perform spectral fitting on our synthetic cubes and compute the resulting rotation velocity (Vrot) and velocity dispersion within 1Re (σe) for a subset of the Auriga sample. We find that the kinematics produced by Auriga are in good agreement with the observations from the SAMI galaxy survey after taking into account the effects of dust and the systematics produced by the observation limitations. We also explore the effects of seeing convolution, inclination, and attenuation on the line-of-sight velocity distribution. For highly inclined galaxies, these effects can lead to an artificial decrease in the measured V/σ by nearly a factor of two (after inclination correction). We also demonstrate the utility of our method for high-redshift galaxies by emulating spatially resolved continuum spectra from the Large Early Galaxy Census (LEGA-C) survey and, looking forward, the European Extremely Large Telescope (E-ELT) High Angular Resolution Monolithic Optical and Near-infrared Integral field spectrograph (HARMONI). Our framework represents a crucial link between the ground truth for stellar populations and kinematics in simulations and the observed stellar continuum observations at low and high redshift.

On the effects of spider-arms vignetting on interferometric measurements of deformable mirrors

The interferometric calibration and measurement of deformable mirrors for adaptive optics are often performed on complex optical system with spider arms. The spider shadows may divide the mirror surface into separate islands on the detector, so the interferometer fails in reconnecting them to a common phase value. The calibration measurements then suffer from such artificial differential pistons across islands, which is converted into a wrong actuator command and in general into a poor calibration. We review the effects of spider arms shadowing as experienced during the optical calibration of large format adaptive mirrors, such as the Large Binocular Telescope and Very Large Telescope ones; we describe the procedures that we tested to cope with these issues and their effectiveness; and we present a laboratory assessment of the effect of such a shadowing with a dedicated test setup. Our work is part of a preparatory activity for the optical test of the European Extremely Large Telescope adaptive mirror M4.