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The transition towards decarbonized power systems requires accounting for the impacts of the climate variability and climate change on renewable energy sources. With the growing share of wind and solar power in the European power system and their strong weather dependence, balancing the energy demand and supply becomes a great challenge. We characterize energy compound events, defined as periods of simultaneous low renewable production of wind and solar power, and high electricity demand. Using a logistic regression approach, we examine the influence of meteorological and atmospheric drivers on energy compound events. Moreover, we assess the spatial coherence of energy compound events that pose a major challenge within an interconnected power grid, as they can affect multiple countries simultaneously. On average, European countries are exposed to winter energy compound events more than twice per year. The combination of extremely low temperatures and low wind speeds is associated with a higher probability of occurrence of energy compound events. Furthermore, we show that blocked weather regimes have a major influence on energy compound events. In particular, Greenland and European blocking lead to widespread energy compound events that affect multiple countries at the same time. Our results highlight the relevance of weather regimes resulting in synchronous spatial energy compound events, which might pose a greater risk within a potential fully interconnected European grid.

Increased tropospheric ozone (O3) and high temperatures affect human health during heat waves. Here, we perform a source attribution that considers separately the formation of German surface ozone from emitted NOx and VOC precursors during two peak ozone events that took place in 2015 and 2018 which were associated with elevated temperatures. Results showed that the peak ozone concentrations can be primarily attributed to nearby emissions of anthropogenic NOx (from Germany and immediately neighboring countries) and biogenic VOC. Outside of these high ozone episodes, baseline ozone concentrations are attributed primarily to long-range transport, with ozone due to remote anthropogenic NOx emissions and methane oxidation adding to the tropospheric ozone background. We show that a significant contribution to modeled O3 coming from German NOx or VOC emissions occurs mostly in southern Germany, emphasizing that the production of ozone depends on the local interplay among NOx and VOC precursors. Shipping activities in the Baltic and North Seas have a large impact on ozone predicted in coastal areas, yet a small amount of ozone from these sources can also be seen far inland, showing the importance of transported ozone on pollution levels. We have also shown that changes in circulation patterns during the peak O3 episodes observed in Germany during the 2015 and 2018 heatwaves can affect the contribution of different NOX emission sources to total O3, thus the possible influence of multiple upwind source regions should be accounted for when mitigation strategies are designed. Our study also highlights the good correlation between ozone coming from German biogenic VOC emissions and total ozone, although the diurnal variation in the ozone coming from biogenic sources is not dominated by the diurnal variation in biogenic emissions, and the peaks of ozone from biogenic sources are disconnected from local emission peaks. This suggests that the formation of O3 from local German biogenic VOC emissions is not the sole factor that influences the ozone formation and other meteorological and chemical processes affect the diel variation of ozone having a biogenic origin. Overall, this study helps to understand the importance of a source attribution method to understand the sources of O3 in Germany and can be a useful tool that will help to design effective mitigation strategies.

Air pollution is a pressing issue that is associated with adverse effects on human health, ecosystems, and climate. Despite many years of effort to improve air quality, nitrogen dioxide (NO2) limit values are still regularly exceeded in Europe, particularly in cities and along streets. This study explores how concentrations of nitrogen oxides (NOx = NO + NO2) in European urban areas have changed over the last decades and how this relates to changes in emissions. To do so, the incremental approach was used, comparing urban increments (i.e. urban background minus rural concentrations) to total emissions, and roadside increments (i.e. urban roadside concentrations minus urban background concentrations) to traffic emissions. In total, nine European cities were assessed. The study revealed that potentially confounding factors like the impact of urban pollution at rural monitoring sites through atmospheric transport are generally negligible for NOx. The approach proves therefore particularly useful for this pollutant. The estimated urban increments all showed downward trends, and for the majority of the cities the trends aligned well with the total emissions. However, it was found that factors like a very densely populated surrounding or local emission sources in the rural area such as shipping traffic on inland waterways restrict the application of the approach for some cities. The roadside increments showed an overall very diverse picture in their absolute values and trends and also in their relation to traffic emissions. This variability and the discrepancies between roadside increments and emissions could be attributed to a combination of local influencing factors at the street level and different aspects introducing inaccuracies to the trends of the emission inventories used, including deficient emission factors. Applying the incremental approach was evaluated as useful for long-term pan-European studies, but at the same time it was found to be restricted to certain regions and cities due to data availability issues. The results also highlight that using emission inventories for the prediction of future health impacts and compliance with limit values needs to consider the distinct variability in the concentrations not only across but also within cities.

Meeting carbon-reduction targets will require to consider climate variability and climate change due the increasing share of climate-sensitive renewable energy sources (RES). In particular, wind and solar power are an important contribution within the energy mix in Europe. However, the strong dependence of RES on weather conditions poses a great challenge to the European power systems. One of the main concerns arises from situations of low production and high demand that can further aggravate the energy system. The purpose of the present study is twofold. Firstly, we characterize energy droughts, identified as periods of low wind and solar production (PWS) and periods of high energy residual load (RL)(i.e. energy demand minus wind and solar production). For that, a bivariate copula modelling approach is used to construct the joint probability distribution of two main characteristics of droughts: duration and severity. Secondly, we examine energy compound events defined as episodes of low PWS and high RL occurring simultaneously. A least absolute shrinkage and selection operator (LASSO) logistic regression is used to model the frequency of energy compound events using relevant meteorological drivers as covariates. Our results show that energy droughts derived from RL are less frequent but last longer than the droughts obtained from PWS that are more frequent although generally shorter. The bivariate frequency analysis indicates that severe droughts of PWS occur less frequent with large return periods at most of the countries. Shorter return periods are found in the case of RL, which points out that European countries experience more often severe droughts of RL. Results from the LASSO logistic regression indicate that temperature plays a relevant role on the occurrence of energy compound events. Overall, a higher likelihood of the occurrence of energy compound events is associated with extreme low wind speeds and low temperatures (

Due to the strong temperature dependence of surface ozone concentrations (O3), future warmer conditions may worsen ozone pollution levels despite continued efforts on emission controls of ozone precursors. Using long-term measurements of hourly O3 concentrations co-located with NOx concentrations in stations distributed throughout Germany, we assess changes in the climate penalty, defined as the slope of ozone-temperature relationship during the period 1999–2018. We find a stronger temperature sensitivity in the urban stations over the southwestern regions, especially in the first period of the study (1999–2008).We show a decrease in the climate penalty in most of stations during the second period of the study (2009–2018), with some exceptions (e.g. Berlin) where the climate penalty did not show significant changes. To examine the impacts of NOx reductions on the O3 sensitivity to temperature, we propose a statistical approach based on generalized additive models (GAMs) to describe ozone production rates, inferred from hourly observations, as a function of NOx and temperature, among other variables relevant during the O3 production. We find lower O3 production rates during the second period (2009–2018) at most stations and a decreasing sensitivity to temperature, pointing out that lowering NOx concentrations resulted in decreasing O3 production rates. However, we also observe changes in the shape of the function representing the O3-temperature relationship, which indicate that NOx reductions alone can not explain the changes in the temperature dependence of O3. Our analysis would suggest that decreasing NOx concentrations are not the only factor causing the observed changes in the climate penalty factor.

Con la finalidad de determinar la periodicidad en la deriva de insectos acuáticos durante un ciclo de 16 horas, en un tramo del Río Gatú, Veraguas, Panamá; se realizaron muestreos una vez por semana, durante los meses de febrero, marzo y abril de 2017, con un total de 13 giras. Para la recolecta de insectos acuáticos en la deriva, se utilizaron dos trampas de deriva, con un área de 0,176 m2 y 500 μm de ojo de malla, colocadas contra corriente, una al lado de la otra. Las trampas de deriva se mantuvieron sumergidas durante todo el periodo de muestreo y se desocuparon cada cuatro horas: de 06:00 a 10:00 h.; de 10:00 a 14:00 h.; de 14:00 a 18:00 h. y de 18:00 a 22:00 h., para un total de ocho muestras por día de recolecta. Se recolectó un total de 1 935 insectos acuáticos, distribuidos en nueve órdenes, 27 familias y 48 géneros. La mayor abundancia de insectos en la deriva en el tramo estudiado del Río Gatú, se registró en los periodos de 6:00 -10:00 h. y 18:00 – 22:00 h.

Climate change is expected to alter global, regional and local meteorological conditions and as a result, the changes in the climate system will play an essential role on future air quality. Tropospheric ozone is considered one of the most harmful pollutants and it is strongly dependent on weather conditions. Therefore, understanding the impacts of near-term climate change on ozone concentrations is crucial for developing effective air quality policies. This dissertation focuses on the analysis of the influence of synoptic and local meteorological conditions on ground-level ozone over Europe and it provides a comprehensive spatial characterization of the most important meteorological key-driving factors of surface ozone concentrations over the whole domain. For this purpose two approaches are proposed: i) a weather types classification and ii) regression methods. Firstly, large-scale atmospheric circulation is examined through a weather types classification, implemented grid cell-by-grid cell over Europe. The ability of a suite of global climate models to reproduce realistic synoptic patterns in the present climate is evaluated against two reanalysis products. Additionally, the association between weather types and anomalies of maximum and minimum temperatures is investigated. In general, the models are able to capture realistic synoptic patterns when compared to the reanalyses. However, some limitations to reproduce the frequencies of certain weather types, such as low flow conditions over South Europe in summer and autumn are found. The projected changes in the frequency of weather types under future climate scenarios reveal an increase of anticyclonic days and warmer conditions affecting the British Isles in summer, and more westerlies and consequently mild winter conditions over Central Europe. As a result of a projected increase of low flow conditions over the Mediterranean basin, stagnant situations would become more frequent, favouring episodes of air pollution. Further analysis indicate that changes in the frequency of weather types represent a minor contribution of the total change of projected European temperatures. Thus, the temperature changes could be attributed to the so-called within-type variations (changes of the weather types themselves). In the context of climate change, that implies that global warming would also affect the characteristics of some weather types over time (i.e., within-type variations) that are associated with warmer temperatures under future conditions. Secondly, the classification of weather types provides an easy physically interpretable framework for assessing the impacts of synoptic conditions on ozone concentrations. A synoptic-regression approach is developed to investigate the effect of both, synoptic and local meteorological conditions on surface ozone over the European domain. It is shown that local meteorological conditions are generally dominant factors influencing surface ozone variability, rather than the synoptic conditions. The results reveal distinctive regional and seasonal patterns of the most influential ozone drivers. In particular, local meteorological conditions have a strong influence over Central and East Europe, where maximum temperature becomes the most important driver of surface ozone in summer and relative humidity along with surface solar radiation in spring. Finally, a multi-model assessment examines the capability of a set of state-of-the-art air quality models to reproduce the observed relationship between meteorological variables and surface ozone. The results show distinctive seasonal and regional performances in the statistical models developed for each dataset (i.e. observations and model outputs). Overall, the air quality models are in better agreement with observations over the regions referred to as internal regions: England, France, Mid-Europe, North Italy and East Europe. On the contrary, they present more limitations over the rest of the regions, referred to as the external regions: Inflow, Scandinavia, Iberian Peninsula, Mediterranean and the Balkans. There is a larger meteorological contribution in the internal regions, especially in summer where the local meteorology plays an important role in photochemical processes. A minor meteorological effect is found in the external regions, probably due to a major influence of the dynamical processes that are not captured by the statistical models. Most of the air quality models tend to overestimate the sensitivity to maximum temperature and solar radiation and none of them are able to capture the strength of the observed relationship between ozone and relative humidity appropriately. Here, dry deposition schemes may be a key for the underestimation of such relationship. Further analysis of the slopes of the ozone-temperature relationship indicates that the air quality models capture the observed relationship between ozone and temperature in most of the internal regions in summer, while in spring they overestimate it in most of the European regions., Da zu erwarten ist, dass der Klimawandel die globalen, regionalen und kommunalen meteorologischen Zustände verändern wird, werden die Veränderungen des Klimasystems eine wesentliche Rolle in Bezug auf die zukünftig Luftqualität spielen. Troposphärisches Ozon gilt als einer der schädlichsten Schadstoffe und ist stark abhängig von den Wetterbedingungen. Die zeitnahen Auswirkungen des Klimawandels zu verstehen ist daher dringend erforderlich, um eine effektive Luftqualitätspolitik zu entwickeln. Diese Doktorarbeit legt den Schwerpunkt auf die Analyse des Einflusses von synoptischen und kommunalen meteorologischen Zuständen auf bodennahes Ozon in Europa und sie liefert eine umfassende räumliche Charakterisierung der wichtigsten Schlüsselfaktoren der Oberflächen-Ozon-Konzentration auf dem gesamten Gebiet. Zu diesem Zweck werden zwei Ansätze vorgeschlagen: i) eine objektive Wetterlagenklassifikation und ii) Regressionsmethoden. Zunächst wird die großflächige atmosphärische Zirkulation durch eine objektiveWetterlagenklassifikation untersucht – umgesetzt in Form von Gitterzelle zu Gitterzelle in Europa. Es wird ein Vergleich zwischen der Fähigkeit mehrerer globaler Klimamodelle realistisch aussehende synoptische Muster im gegenwärtigen Klima zu reproduzieren einerseits und neuen Darlegungen andererseits aufgestellt und anschließend ausgewertet. Darüber hinaus wird der Zusammenhang zwischen Wetterarten und Anomalien von Maximal- und Mindesttemperaturen untersucht. Im Vergleich mit den neuen Darlegungen können die Modelle im Allgemeinen realistische synoptische Muster erfassen. Allerdings gibt es einige Einschränkungen in der Reproduktion der Frequenzen bestimmter Wetterarten, wie z. B. niedrige Strömungsbedingungen über Südeuropa im Sommer und Herbst. Die prognostizierten Veränderungen bezüglich der Häufigkeit der Wetterarten unter zukünftigen Klimaszenarien zeigen einen Anstieg antizyklonischer Tage und wärmeren Bedingungen, die die britischen Inseln im Sommer beeinflussen, sowie mehrere Westwindzonen, welche folglich mildeWinterbedingungen über Mitteleuropa hervorbringen. Infolge einer prognostizierten Zunahme der niedrigen Strömungsbedingungen über dem Mittelmeerraum würden stagnierende Situationen häufiger vorkommen, was die Folgen der Luftverschmutzung begünstigt. Eine Analyse des Abbaus zur Beurteilung der Auswirkungen der Frequenzänderungen auf die prognostizierten Temperaturen deutet darauf hin, dass Veränderungen in der Häufigkeit derWetterarten einen geringen Beitrag zur Gesamtveränderung der europäischen Temperaturen darstellen. So könnten die Temperaturveränderungen den sogenannten In-Typ-Variationen (selbst Änderungen der Wetterarten) zugeschrieben werden. Im Kontext des Klimawandels bedeutet dies, dass die globale Erwärmung auch die Eigenschaften einiger Wetterarten im Laufe der Zeit beeinflussen würde (d.h. In-Typ-Variationen ), die mit wärmeren Temperaturen unter zukünftigen Bedingungen verbunden sind. Zweitens bietet die Einordnung von Wetterarten einen einfachen physikalisch interpretierbaren Rahmen, um die Auswirkungen von synoptischen Bedingungen auf die Ozonkonzentration zu bewerten. Ein Ansatz der synoptischen Regression wird entwickelt, um die Wirkung von sowohl synoptischen als auch kommunalen meteorologischen Bedingungen auf Oberflächen-Ozon auf europäischem Gebiet zu untersuchen. Es wird gezeigt, dass kommunale meteorologische Bedingungen in der Regel dominierende Faktoren sind, die die Oberflächen-Ozon-Variabilität beeinflussen, und nicht synoptische Bedingungen. Die Ergebnisse zeigen regionale und saisonale Muster der einflussreichsten Ozon Treiber. Die Ozon- Persistenz (vom Vortag) ist auch als Prädiktor enthalten und scheint eine wesentliche Rolle über Südeuropa zu spielen, wohingegen die kommunalen/ regionalen meteorologischen Bedingungen einen starken Einfluss auf Mittel- und Osteuropa haben. Besonders die Maximaltemperatur und relative Luftfeuchtigkeit sind der wichtigste Treiber für Oberflächen-Ozon im Sommer zusammen mit Oberflächen- Sonnenstrahlung im Frühling. Der letzte Teil der Doktorarbeit untersucht eine Multimodell-Bewertung der Fähigkeit einer Reihe von hochmodernen Modellen zur Luftqualität, um die beobachtete Beziehung zwischen meteorologischen Variablen und Oberflächen-Ozon zu reproduzieren. Die Ergebnisse zeigen deutliche saisonale und regionale Leistungen der statistischen Modellen, die für jeden Datensatz (d. H. Beobachtungen und Modellausgaben) entwickelt wurden. Insgesamt stehen die Luftqualitätsmodelle in größerer Übereinstimmung zu den Beobachtungen über die Regionen, welche als folgende interne Regionen bezeichnet werden: England, Frankreich, Mitteleuropa, Norditalien und Osteuropa. Dem gegenübergestellt sind Regionen, welche mehr Einschränkungen gegenüber den übrigen Regionen haben. Solche werden als äußere Regionen bezeichnet: Inflow, Skandinavien, die Iberische Halbinsel, das Mittelmeer und die Balkanstaaten. Es gibt einen größeren meteorologischen Beitrag in den internen Regionen, vor allem im Sommer, wo die lokale Meteorologie eine wichtige Rolle bei photochemischen Prozessen spielt. Eine kleinere meteorologische Wirkung findet sich in den äußeren Regionen, vermutlich aufgrund eines großen Einflusses der dynamischen Prozesse, die nicht durch die statistischen Modelle erfasst werden. Die meisten Luftqualitätsmodelle neigen dazu, die Empfindlichkeit gegen Maximaltemperatur und Sonneneinstrahlung zu überschätzen, und keines von ihnen kann die Stärke der beobachteten Wechselwirkung zwischen Ozon und relativer Feuchtigkeit passend erfassen. Hier könnten trockene Ablagerungsschemata ein Lösungsansatz für die Unterschätzung einer solchen Beziehung bieten. Eine weitere Analyse des Anstiegs der Beziehung zwischen Ozon und Temperatur deutet darauf hin, dass die Luftqualitätsmodelle die beobachtete Beziehung zwischen Ozon und Temperatur in den meisten internen Regionen im Sommer einfangen, während sie diese im Frühjahr sie in den meisten europäischen Regionen überschätzen.

The implementation of European emission abatement strategies has led to a significant reduction in the emissions of ozone precursors during the last decade. Ground-level ozone is also influenced by meteorological factors such as temperature, which exhibit interannual variability and are expected to change in the future. The impacts of climate change on air quality are usually investigated through air-quality models that simulate interactions between emissions, meteorology and chemistry. Within a multi-model assessment, this study aims to better understand how air-quality models represent the relationship between meteorological variables and surface ozone concentrations over Europe. A multiple linear regression (MLR) approach is applied to observed and modelled time series across 10 European regions in springtime and summertime for the period of 2000-2010 for both models and observations. Overall, the air-quality models are in better agreement with observations in summertime than in springtime and particularly in certain regions, such as France, central Europe or eastern Europe, where local meteorological variables show a strong influence on surface ozone concentrations. Larger discrepancies are found for the southern regions, such as the Balkans, the Iberian Peninsula and the Mediterranean basin, especially in springtime. We show that the air-quality models do not properly reproduce the sensitivity of surface ozone to some of the main meteorological drivers, such as maximum temperature, relative humidity and surface solar radiation. Specifically, all air-quality models show more limitations in capturing the strength of the ozone-relative-humidity relationship detected in the observed time series in most of the regions, for both seasons. Here, we speculate that dry-deposition schemes in the air-quality models might play an essential role in capturing this relationship. We further quantify the relationship between ozone and maximum temperature (mo3−T, climate penalty) in observations and air-quality models. In summertime, most of the air-quality models are able to reproduce the observed climate penalty reasonably well in certain regions such as France, central Europe and northern Italy. However, larger discrepancies are found in springtime, where air-quality models tend to overestimate the magnitude of the observed climate penalty.