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Worldwide, academics and practitioners are developing ‘planning-oriented’ approaches to reduce the negative impacts of car traffic for more sustainable urban and transport development. One such example is the design of car-reduced neighborhoods, although these are controversial issues in the hegemonic ‘system’ of automobility. Despite the reduction of emissions and frequent recognition as ‘best practice examples’, ‘planning-critical’ research questions the underlying objectives and narratives of such sustainable developments. Our study contributes to this research perspective by improving the understanding of narratives that emerge along with car-reduced housing developments. For this purpose, we analyze two car-reduced neighborhoods in the City of Darmstadt (Germany) by conducting interviews with different actors involved in the planning and implementation processes. Our investigation reveals that the development of car-reduced neighborhoods (i) is consciously embedded in the context of sustainability, (ii) is characterized by power relations, (iii) follows normative indicators, and (iv) does not always correspond to lived realities. Altogether, the traced narratives of car-reduced neighborhoods are embedded in the overarching debate on sustainability, while at the same time revealing the dependence of society on the automobile. Thus, the hegemonic ‘system’ of automobility—although it is beginning to crack—continues to exist.
Abiotic formation of n-alkane hydrocarbons has been postulated to occur within Earth's crust. Apparent evidence was primarily based on uncommon carbon and hydrogen isotope distribution patterns that set methane and its higher chain homologues apart from biotic isotopic compositions associated with microbial production and closed system thermal degradation of organic matter. Here, we present the first global investigation of the carbon and hydrogen isotopic compositions of n-alkanes in volcanic-hydrothermal fluids hosted by basaltic, andesitic, trachytic and rhyolitic rocks. We show that the bulk isotopic compositions of these gases follow trends that are characteristic of high temperature, open system degradation of organic matter. In sediment-free systems, organic matter is supplied by surface waters (seawater, meteoric water) circulating through the reservoir rocks. Our data set strongly implies that thermal degradation of organic matter is able to satisfy isotopic criteria previously classified as being indicative of abiogenesis. Further considering the ubiquitous presence of surface waters in Earth’s crust, abiotic hydrocarbon occurrences might have been significantly overestimated.
To quantify water flows between groundwater (GW) and surface water (SW) as well as the impact of Abstract. To quantify water flows between groundwater (GW) and surface water (SW) as well as the impact of capillary rise on evapotranspiration by global hydrological models (GHMs), it is necessary to replace the bucket-like linear GW reservoir model typical for hydrological models with a fully integrated gradient-based GW flow model. Linear reservoir models can only simulate GW discharge to SW bodies, provide no information on the location of the GW table and assume that there is no GW flow among grid cells. A gradient-based GW model simulates not only GW storage but also hydraulic head, which together with information on SW table elevation enables the quantification of water flows from GW to SW and vice versa. In addition, hydraulic heads are the basis for calculating lateral GW flow among grid cells and capillary rise.
G³M is a new global gradient-based GW model with a spatial resolution of 5' that will replace the current linear GW reservoir in the 0.5° WaterGAP Global Hydrology Model (WGHM). The newly developed model framework enables inmemory coupling to WGHM while keeping overall runtime relatively low, allowing sensitivity analyses and data assimilation. This paper presents the G³M concept and specific model design decisions together with results under steady-state naturalized conditions, i.e. neglecting GW abstractions. Cell-specific conductances of river beds, which govern GW-SW interaction, were determined based on the 30'' steady-state water table computed by Fan et al. (2013). Together with an appropriate choice for the effective elevation of the SW table within each grid cell, this enables a reasonable simulation of drainage from GW to SW such that, in contrast to the GW model of de Graaf et al. (2015, 2017), no additional drainage based on externally provided values for GW storage above the floodplain is required in G³M. Comparison of simulated hydraulic heads to observations around the world shows better agreement than de Graaf et al. (2015). In addition, G³M output is compared to the output of two established macro-scale models for the Central Valley, California, and the continental United States, respectively. As expected, depth to GW table is highest in mountainous and lowest in flat regions. A first analysis of losing and gaining rivers and lakes/wetlands indicates that GW discharge to rivers is by far the dominant flow, draining diffuse GW recharge, such that lateral flows only become a large fraction of total diffuse and focused recharge in case of losing rivers and some areas with very low GW recharge. G³M does not represent losing rivers in some dry regions. This study presents the first steps towards replacing the linear GW reservoir model in a GHM while improving on recent efforts, demonstrating the feasibility of the approach and the robustness of the newly developed framework.
In global hydrological models, groundwater (GW) is typically represented by a bucket-like linear groundwater reservoir. Reservoir models, however, (1) can only simulate GW discharge to surface water (SW) bodies but not recharge from SW to GW, (2) provide no information on the location of the GW table, and (3) assume that there is no GW flow among grid cells. This may lead, for example, to an underestimation of groundwater resources in semiarid areas where GW is often replenished by SW or to an underestimation of evapotranspiration where the GW table is close to the land surface. To overcome these limitations, it is necessary to replace the reservoir model in global hydrological models with a hydraulic head gradient-based GW flow model.
We present G3M, a new global gradient-based GW model with a spatial resolution of 5′ (arcminutes), which is to be integrated into the 0.5∘ WaterGAP Global Hydrology Model (WGHM). The newly developed model framework enables in-memory coupling to WGHM while keeping overall runtime relatively low, which allows sensitivity analyses, calibration, and data assimilation. This paper presents the G3M concept and model design decisions that are specific to the large grid size required for a global-scale model. Model results under steady-state naturalized conditions, i.e., neglecting GW abstractions, are shown. Simulated hydraulic heads show better agreement to observations around the world compared to the model output of de Graaf et al. (2015). Locations of simulated SW recharge to GW are found, as is expected, in dry and mountainous regions but areal extent of SW recharge may be underestimated. Globally, GW discharge to rivers is by far the dominant flow component such that lateral GW flows only become a large fraction of total diffuse and focused recharge in the case of losing rivers, some mountainous areas, and some areas with very low GW recharge. A strong sensitivity of simulated hydraulic heads to the spatial resolution of the model and the related choice of the water table elevation of surface water bodies was found. We suggest to investigate how global-scale groundwater modeling at 5′ spatial resolution can benefit from more highly resolved land surface elevation data.
Analysis of stratospheric transport from an observational point of view is frequently realized by evaluation of mean age of air values from long-lived trace gases. However, this provides more insight into general transport strength and less into its mechanism. Deriving complete transit time distributions (age spectra) is desirable, but their deduction from direct measurements is difficult and so far primarily achieved by assumptions about dynamics and spectra themselves. This paper introduces a modified version of an inverse method to infer age spectra from mixing ratios of short-lived trace gases. For a full description of transport seasonality the formulation includes an imposed seasonal cycle to gain multimodal spectra. The EMAC model simulation used for a proof of concept features an idealized dataset of 40 radioactive trace gases with different chemical lifetimes as well as 40 chemically inert pulsed trace gases to calculate pulse age spectra. Annual and seasonal mean inverse spectra are compared to pulse spectra including first and second moments as well as the ratio between them to assess the performance on these time scales. Results indicate that the modified inverse age spectra match the annual and seasonal pulse age spectra well on global scale beyond 1.5 years mean age of air. The imposed seasonal cycle emerges as a reliable tool to include transport seasonality in the age spectra. Below 1.5 years mean age of air, tropospheric influence intensifies and breaks the assumption of single entry through the tropical tropopause, leading to inaccurate spectra in particular in the northern hemisphere. The imposed seasonal cycle wrongly prescribes seasonal entry in this lower region and does not lead to a better agreement between inverse and pulse age spectra without further improvement. As the inverse method aims for future implementation on in situ observational data, possible critical factors for this purpose are delineated finally.
Deriving stratospheric age of air spectra using an idealized set of chemically active trace gases
(2019)
Analysis of stratospheric transport from an observational point of view is frequently realized by evaluation of the mean age of air values from long-lived trace gases. However, this provides more insight into general transport strength and less into its mechanism. Deriving complete transit time distributions (age spectra) is desirable, but their deduction from direct measurements is difficult. It is so far primarily based on model work. This paper introduces a modified version of an inverse method to infer age spectra from mixing ratios of short-lived trace gases and investigates its basic principle in an idealized model simulation. For a full description of transport seasonality the method includes an imposed seasonal cycle to gain multimodal spectra. An ECHAM/MESSy Atmospheric Chemistry (EMAC) model simulation is utilized for a general proof of concept of the method and features an idealized dataset of 40 radioactive trace gases with different chemical lifetimes as well as 40 chemically inert pulsed trace gases to calculate pulse age spectra. It is assessed whether the modified inverse method in combination with the seasonal cycle can provide matching age spectra when chemistry is well-known. Annual and seasonal mean inverse spectra are compared to pulse spectra including first and second moments as well as the ratio between them to assess the performance on these timescales. Results indicate that the modified inverse age spectra match the annual and seasonal pulse age spectra well on global scale beyond 1.5 years of mean age of air. The imposed seasonal cycle emerges as a reliable tool to include transport seasonality in the age spectra. Below 1.5 years of mean age of air, tropospheric influence intensifies and breaks the assumption of single entry through the tropical tropopause, leading to inaccurate spectra, in particular in the Northern Hemisphere. The imposed seasonal cycle wrongly prescribes seasonal entry in this lower region and does not lead to a better agreement between inverse and pulse age spectra without further improvement. Tests with a focus on future application to observational data imply that subsets of trace gases with 5 to 10 species are sufficient for deriving well-matching age spectra. These subsets can also compensate for an average uncertainty of up to ±20 % in the knowledge of chemical lifetime if a deviation of circa ±10 % in modal age and amplitude of the resulting spectra is tolerated.
Im Beitrag entwickeln wir einen kritischen Blick auf die Geographie der Wahlergebnisse der Alternative für Deutschland (AfD) bei den Bundestagswahlen 2017. Wir hinterfragen Erklärungsmuster, die in einem starren Stadt-Land-Gegensatz verhaftet bleiben und die komplexe Prozesshaftigkeit der Urbanisierung ignorieren. Dagegen gehen wir mit Henri Lefebvre und Theodor W. Adorno vom Urbanen und Ruralen als sozialen Verhältnissen aus, die sich im übergeordneten Prozess der Urbanisierung in dialektischer Weise scheiden sowie räumlich im Spannungsverhältnis von Zentrum und Peripherie materialisieren. Beispielhaft illustrieren wir diesen Prozess in der Diskussion von drei unterschiedlichen Orten, an denen die AfD bei den Bundestagswahlen besonders erfolgreich war: dem Landkreis Vorpommern-Greifswald als Fall einer umfassenden Peripherisierung, dem Quartier Pforzheim-Haidach als peripheres Zentrum und dem Stadtteil Mannheim-Schönau als zentrale Peripherie. Der Beitrag versucht damit eine räumliche Perspektive auf aktuelle Erfolge des Rechtspopulismus zu entwickeln wie auch Stadt-Land-Verhältnisse konzeptionell neu zu erfassen.
Understanding new particle formation and growth is important because of the strong impact of these processes on climate and air quality. Measurements to elucidate the main new particle formation mechanisms are essential; however, these mechanisms have to be implemented in models to estimate their impact on the regional and global scale. Parameterizations are computationally cheap ways of implementing nucleation schemes in models but they have their limitations, as they do not necessarily include all relevant parameters. Process models using sophisticated nucleation schemes can be useful for the generation of look-up tables in large scale models or for the analysis of individual new particle formation events. In addition, some other important properties can be derived from a process model that implicitly calculates the evolution of the full aerosol size distribution, e.g., the particle growth rates. Within this study, a model (SANTIAGO, Sulfuric acid Ammonia NucleaTIon And GrOwth model) is constructed that simulates new particle formation starting from the monomer of sulfuric acid up to a particle size of several hundred nanometers. The smallest sulfuric acid clusters containing one to four acid molecules and varying amount of base (ammonia) are allowed to evaporate in the model, whereas growth beyond the pentamer (5 sulfuric acid molecules) is assumed to be entirely collision-controlled. The main goal of the present study is to derive appropriate thermodynamic data needed to calculate the cluster evaporation rates as a function of temperature. These data are derived numerically from CLOUD (Cosmics Leaving OUtdoor Droplets) chamber new particle formation rates for neutral sulfuric acid-water-ammonia nucleation at temperatures between 208 K and 292 K. The numeric methods include an optimization scheme to derive the best estimates for the thermodynamic data (dH and dS) and a Monte Carlo method to derive their probability density functions. The derived data are compared to literature values. Using different data sets for dH and dS in SANTIAGO detailed comparison between model results and measured CLOUD new particle formation rates is discussed.
Understanding new particle formation and growth is important because of the strong impact of these processes on climate and air quality. Measurements to elucidate the main new particle formation mechanisms are essential; however, these mechanisms have to be implemented in models to estimate their impact on the regional and global scale. Parameterizations are computationally cheap ways of implementing nucleation schemes in models, but they have their limitations, as they do not necessarily include all relevant parameters. Process models using sophisticated nucleation schemes can be useful for the generation of look-up tables in large-scale models or for the analysis of individual new particle formation events. In addition, some other important properties can be derived from a process model that implicitly calculates the evolution of the full aerosol size distribution, e.g., the particle growth rates. Within this study, a model (SANTIAGO – Sulfuric acid Ammonia NucleaTIon And GrOwth model) is constructed that simulates new particle formation starting from the monomer of sulfuric acid up to a particle size of several hundred nanometers. The smallest sulfuric acid clusters containing one to four acid molecules and a varying amount of base (ammonia) are allowed to evaporate in the model, whereas growth beyond the pentamer (five sulfuric acid molecules) is assumed to be entirely collision-controlled. The main goal of the present study is to derive appropriate thermodynamic data needed to calculate the cluster evaporation rates as a function of temperature. These data are derived numerically from CLOUD (Cosmics Leaving OUtdoor Droplets) chamber new particle formation rates for neutral sulfuric acid–water–ammonia nucleation at temperatures between 208 and 292 K. The numeric methods include an optimization scheme to derive the best estimates for the thermodynamic data (dH and dS) and a Monte Carlo method to derive their probability density functions. The derived data are compared to literature values. Using different data sets for dH and dS in SANTIAGO detailed comparison between model results and measured CLOUD new particle formation rates is discussed.
Parabens and sorbic acid are commonly used as food preservatives due to their antimicrobial effect. However, their use in foods for infants and young children is not permitted in the European Union. Previous studies found these compounds in some gel-filled baby teethers, whereby parabens, which are well-known as endocrine disruptors, were identified in the polymer-based chewing surface consisting of ethylene-vinyl acetate (EVA). To assess the exposure of infants and young children to these products, the application of parabens in teethers should be thoroughly investigated. Therefore, the present study aimed to apply a representative migration test procedure combined with an accurate analytical method to examine gel-filled baby teethers without elaborate sample preparation, high costs, and long processing times. Accordingly, solid-phase extraction (SPE), in combination with a stable isotope dilution assay (SIDA) and subsequent gas chromatography–mass spectrometry (GC–MS) for analysis of methyl-, ethyl-, and n-propylparaben (MeP, EtP, and n-PrP), was found to be well-suited, with recoveries ranging from 93 to 99%. The study compared the release of these parabens from intact teether surfaces into water and saliva simulant under real-life conditions, with total amounts of detected parabens found to be in the range of 101–162 µg 100 mL−1 and 57–148 µg 100 mL−1, respectively. Furthermore, as a worst-case scenario, the release into water was examined using a long-term migration study.
Here we present a comprehensive attempt to correlate aragonitic Na / Ca ratios from Lophelia pertusa, Madrepora oculata and a caryophylliid cold-water coral (CWC) species with different seawater parameters such as temperature, salinity and pH. Living CWC specimens were collected from 16 different locations and analyzed for their Na / Ca content using solution-based inductively coupled plasma-optical emission spectrometry (ICP-OES) measurements. The results reveal no apparent correlation with salinity (30.1–40.57 g/kg) but a significant inverse correlation with temperature (−0.31 mmol/mol/°C). Other marine aragonitic organisms such as Mytilus edulis (inner aragonitic shell portion) and Porites sp. exhibit similar results highlighting the consistency of the calculated CWC regressions. Corresponding Na / Mg ratios show a similar temperature sensitivity to Na / Ca ratios, but the combination of two ratios appear to reduce the impact of vital effects and domain-dependent geochemical variation. The high degree of scatter and elemental heterogeneities between the different skeletal features in both Na / Ca and Na / Mg however limit the use of these ratios as a proxy and/or make a high number of samples necessary. Additionally, we explore two models to explain the observed temperature sensitivity of Na / Ca ratios for an open and semi-enclosed calcifying space based on temperature sensitive Na and Ca pumping enzymes and transport proteins that change the composition of the calcifying fluid and consequently the skeletal Na / Ca ratio.
In late 2013, a whole air flask collection program started at the Taunus Observatory (TO) in central Germany. Being a rural site in close vicinity to the densely populated Rhein-Main area, Taunus Observatory allows to assess local and regional emissions. Owed to its altitude of 825 m, the site also regularly experiences background conditions, especially when air masses approach from north-westerly directions. With a large footprint area mainly covering central Europe north of the Alps, halocarbon measurements at the site have the potential to improve the data base for estimation of regional and total European halogenated greenhouse gas emissions. Flask samples are collected weekly for offline analysis using a GC-MS system employing a quadrupole as well as a time-of-flight mass spectrometer. As background reference, additional samples are collected approximately bi-weekly at the Mace Head Atmospheric Research Station (MHD) when air masses approach from the site’s clean air sector. Thus the TO time series can be linked to the in-situ AGAGE measurements and the NOAA flask sampling program at MHD. An iterative baseline identification procedure separates polluted samples from baseline data. While there is good agreement of baseline mixing ratios between TO and MHD, with a larger variability of mixing ratios at the continental site, measurements at TO are regularly influenced by elevated halocarbon mixing ratios. Here, first time series are presented for CFC-11, CFC-12, HCFC-22, HFC-134a, HFC-227ea, HFC-245fa, and dichloromethane. While atmospheric mixing ratios of the CFCs decrease, they increase for the HCFC and the HFCs. Small unexpected differences between CFC-11 and CFC-12 are found with regard to the occurrence of high mixing ratio events and seasonality, although production and use of both compounds are strictly regulated by the Montreal Protocol, and therefore a similar decrease of atmospheric mixing ratios should occur. Dichloromethane, a solvent about which recently concerns have risen regarding its growing influence on stratospheric ozone depletion, does not show a significant trend with regard to both, baseline mixing ratios and the occurrence of pollution events at Taunus Observatory for the time period covered, indicating stable emissions in the regions that influence the site. An analysis of HYSPLIT trajectories reveals differences in halocarbon mixing ranges depending on air mass origin.
In late 2013, a whole air flask collection programme was started at Taunus Observatory (TO) in central Germany. Being a rural site in close proximity to the Rhine–Main area, Taunus Observatory allows assessment of emissions from a densely populated region. Owing to its altitude of 825 m, the site also regularly experiences background conditions, especially when air masses approach from north-westerly directions. With a large footprint area mainly covering central Europe north of the Alps, halocarbon measurements at the site have the potential to improve the database for estimation of regional and total European halogenated greenhouse gas emissions. Flask samples are collected weekly for offline analysis using a GC/MS system simultaneously employing a quadrupole as well as a time-of-flight mass spectrometer. As background reference, additional samples are collected approximately once every 2 weeks at the Mace Head Atmospheric Research Station (MHD) when air masses approach from the site's clean air sector. Thus the time series at TO can be linked to the in situ AGAGE measurements and the NOAA flask sampling programme at MHD. An iterative baseline identification procedure separates polluted samples from baseline data. While there is good agreement of baseline mixing ratios between TO and MHD, with a larger variability of mixing ratios at the continental site, measurements at TO are regularly influenced by elevated halocarbon mixing ratios. Here, first time series are presented for CFC-11, CFC-12, HCFC-22, HFC-134a, HFC-227ea, HFC-245fa, and dichloromethane. While atmospheric mixing ratios of the chlorofluorocarbons (CFCs) decrease, they increase for the hydrochlorofluorocarbons (HCFCs) and the hydrofluorocarbons (HFCs). Small unexpected differences between CFC-11 and CFC-12 are found with regard to frequency and relative enhancement of high mixing ratio events and seasonality, although production and use of both compounds are strictly regulated by the Montreal Protocol, and therefore a similar decrease in atmospheric mixing ratios should occur. Dichloromethane, a solvent about which recently concerns have been raised regarding its growing influence on stratospheric ozone depletion, does not show a significant trend with regard to both baseline mixing ratios and the occurrence of pollution events at Taunus Observatory for the time period covered, indicating stable emissions in the regions that influence the site. An analysis of trajectories from the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model reveals differences in halocarbon mixing ranges depending on air mass origin.
Nach einer Pressemitteilung des Statistischen Bundesamtes (2018) hatten von allen in Deutschland erfassten Lohn- und Einkommensteuerpflichtigen 19.000 Einkünfte von mindestens einer Million Euro. Dass Arbeit aber nicht die vorrangige Methode ist, um reich zu werden und zu bleiben, kann man daran erkennen, dass die Zahl der High-Net-Worth-Individuals (HNWI) mit mehr als einer Million Euro Vermögen jene der Einkommensmillionär_innen im Jahr 2017 um 1.345.600 in Deutschland überstieg. Auch die Entwicklung der HNWI ist in Deutschland günstiger als die der Einkommensmillionär_innen. Dem Statistischen Bundesamt zufolge nahm die Zahl der Einkommensmillionär_innen von 2013 bis 2018 "lediglich" um 1.600 zu (Statistisches Bundesamt 2018). Dem World Wealth Report 2018 von Capgemini zufolge konnten sich aber alleine von 2016 bis 2017 85.000 Personen mehr in Deutschland als HNWI bezeichnen (Capgemini 2018). Ganz offensichtlich ist Arbeit weniger erfolgversprechend, wenn man sich auf den Weg machen will, Millionär_in zu werden. Dies gilt nicht nur in Deutschland, sondern ist ein weit verbreitetes Phänomen. Es hat ganz einfach damit zu tun, dass Vermögen geringer besteuert wird als das Einkommen.
Die Verwaltung der unternehmerischen Stadt : (k)ein Thema in der geographischen Stadtforschung?!
(2018)
In der geographischen Stadtforschung finden sich allgemeine Verweise darauf, dass zum Kanon neoliberaler Reskalierung und urbaner Transformation auch die Einführung von New Public Management in den Städten westlicher Industriestaaten zählt. Daran anschließend argumentiere ich, dass das, was ich als die Verwaltung der unternehmerischen Stadt zusammenfasse, nicht lediglich das Ergebnis abstrakter Neoliberalisierungsprozesse oder technokratischer Modernisierung eines mechanischen Exekutivapparats darstellt. In dem Beitrag zeige ich auf, dass die betriebswirtschaftlich reformierte Verwaltung Effekt und wichtiges Terrain der Ausarbeitung, Artikulation und Durchsetzung einer unternehmerischen Stadtpolitik ist.
A new method for size resolved chemical analysis of nucleation mode aerosol particles (size range from ~10 to ~30 nm) is presented. The Thermal Desorption Differential Mobility Analyzer (TD-DMA) uses an online, discontinuous principle. The particles are charged, a specific size is selected by differential mobility analysis and they are collected on a filament by electrostatic precipitation. Subsequently, the sampled mass is evaporated in a clean carrier gas and analyzed by a chemical ionization mass spectrometer. Gas phase measurements are performed with the same mass spectrometer during the sampling of particles. The characterization shows reproducible results, with a particle size resolution of 1.19 and the transmission efficiency for 15 nm particles being slightly above 50 %. The signal from the evaporation of a test substance can be detected starting from 0.01 ng and shows a linear response in the mass spectrometer. Instrument operation in the range of pg/m3 is demonstrated by an example measurement of 15 nm particles produced by nucleation from dimethylamine, sulfuric acid and water.
A new method for size-resolved chemical analysis of nucleation mode aerosol particles (size range from ∼10 to ∼30 nm) is presented. The Thermal Desorption Differential Mobility Analyzer (TD-DMA) uses an online, discontinuous principle. The particles are charged, a specific size is selected by differential mobility analysis and they are collected on a filament by electrostatic precipitation. Subsequently, the sampled mass is evaporated in a clean carrier gas and analyzed by a chemical ionization mass spectrometer. Gas-phase measurements are performed with the same mass spectrometer during the sampling of particles. The characterization shows reproducible results, with a particle size resolution of 1.19 and the transmission efficiency for 15 nm particles being slightly above 50 %. The signal from the evaporation of a test substance can be detected starting from 0.01 ng and shows a linear response in the mass spectrometer. Instrument operation in the range of pg m−3 is demonstrated by an example measurement of 15 nm particles produced by nucleation from dimethylamine, sulfuric acid and water.
The multi-valence nature of vanadium means that its geochemical behaviour will be ƒO2-dependent, so that its concentration or V/Sc (or V/Ga), can serve as proxies for oxidation state in mantle peridotites. Compared to Fe3+/Fe2+-based equilibria, such trace elements may be less sensitive to metasomatic processes. To investigate these systematics, we have measured V, Sc, Ga and Fe3+ contents in clinopyroxene from well-characterised spinel peridotite xenoliths from the Massif Central, France. These samples were metasomatised by a variety of agents with different oxidation states.V contents can be modified by metasomatic interactions, and other geochemically similar elements including Sc and Ga can also be added, removed or remain constant. A link between V/Sc and Fe3+-Fe2+ equilibria is apparent. Partial removal of V is caused by different metasomatic agents; the common factor is that all agents were significantly more oxidised than the initial ambient mantle peridotite. This extraction can be understood by a decreasing partition coefficient for V for ΔlogƒO2 > ~FMQ-2. Considering that mineral/melt partitioning of V decreases similarly for all peridotite minerals, the bulk-rock V/Sc will also change during relatively oxidising metasomatic interactions and mirror the results obtained for clinopyroxene.
The social construction of technological stasis : the stagnating data structure in OpenStreetMap
(2018)
The article aims for examining the ‘technological stasis’ of the data structure in OpenStreetMap – the successful global collaborative geodata project devoted to ‘create and distribute free geographic data for the world’. Digital structures are strongly influenced by continuing stagnation. This technological stasis – the lack of change in technology – influences data in various ways, as demonstrated by the intensive discussion of the issue by computer scientists and software engineers. However, existing research describing stagnating software is often technic centred and fuzzy, while critical research is barely considering issues of technological stasis in the digital context at all. Therefore, this paper aims for enriching this body of knowledge in order to shed light on aging data structures. I reframe technological stasis with a social-constructivist perspective – using the approach of Social Construction of Technology – especially with the concept of technological frames. Based on the case example of OpenStreetMap, my findings suggest that the data structure – and its stasis – is the outcome of competing understandings and perspectives, shaped by power asymmetries. Although the data structure did not significantly change for more than 10 years, I demonstrate that this is not because of a lack of motivation, nor technological difficulties of carrying out such changes. The technological stasis is rather rooted in the dominant position of few project members who are able to change the software design; it is their perception of the project that defines how data should be stored and what features are dispensable.
Subduction zone magmas are more oxidised on eruption than those at mid-ocean ridges. This is attributed either to oxidising components, derived from subducted lithosphere (slab) and added to the mantle wedge, or to oxidation processes occurring during magma ascent via differentiation. Here we provide direct evidence for contributions of oxidising slab agents to melts trapped in the sub-arc mantle. Measurements of sulfur (S) valence state in sub-arc mantle peridotites identify sulfate, both as crystalline anhydrite (CaSO4) and dissolved SO42− in spinel-hosted glass (formerly melt) inclusions. Copper-rich sulfide precipitates in the inclusions and increased Fe3+/∑Fe in spinel record a S6+–Fe2+ redox coupling during melt percolation through the sub-arc mantle. Sulfate-rich glass inclusions exhibit high U/Th, Pb/Ce, Sr/Nd and δ34S (+ 7 to + 11‰), indicating the involvement of dehydration products of serpentinised slab rocks in their parental melt sources. These observations provide a link between liberated slab components and oxidised arc magmas.
In der rezensierten Monographie gelingt es, "New Public Management" als strategisches und politisches Projekt auszudeuten. Die Konsequenzen für die Liegenschaftspolitik können fundiert dargelegt werden. In der Rezension wird eine Einordnung in die bisherige Forschung sowie eine kritische Würdigung der rezensierten Arbeit versucht.
Innerhalb der Gentrifizierungsforschung analysiert die Rent‑Gap‑Theorie, wie kleinräumige Differenzen zwischen gegenwärtigen Verwertungsbedingungen einerseits sowie Erwartungen auf zukünftig steigende Mieten andererseits Verdrängungsprozesse antreiben. Dementgegen hat Eric Clark (2014) jüngst eingefordert, dass die Stadtforschung den Blick verstärkt darauf richten müsse, wie Verdrängung verhindert werden kann. Diesen Appell aufgreifend, zeigen wir bezogen auf den deutschen Kontext, inwiefern mietrechtliche Regularien, stadtplanerische Entscheidungen und die jeweilige Eigentümerstruktur wesentlich darüber entscheiden, ob sich ein immobilienwirtschaftlicher Verwertungsdruck auch tatsächlich in Verdrängungsprozesse übersetzt. Illustriert wird dies am Wandel der Eigentümerstruktur im Frankfurter Gallus seit den 1970er Jahren. Deutlich wird dabei, dass Gentrifizierung kein Naturgesetz darstellt, sondern ein zutiefst politischer Prozess ist, der sich effektiv verhindern lässt.
During the Holocene, North American ice sheet collapse and rapid sea-level rise reconnected the Black Sea with the global ocean. Rapid meltwater releases into the North Atlantic and associated climate change arguably slowed the pace of Neolithisation across southeastern Europe, originally hypothesized as a catastrophic flooding that fueled culturally-widespread deluge myths. However, we currently lack an independent record linking the timing of meltwater events, sea-level rise and environmental change with the timing of Neolithisation in southeastern Europe. Here, we present a sea surface salinity record from the Northern Aegean Sea indicative of two meltwater events at ~8.4 and ~7.6 kiloyears that can be directly linked to rapid declines in the establishment of Neolithic sites in southeast Europe. The meltwater events point to an increased outflow of low salinity water from the Black Sea driven by rapid sea level rise >1.4 m following freshwater outbursts from Lake Agassiz and the final decay of the Laurentide ice sheet. Our results shed new light on the link between catastrophic sea-level rise and the Neolithisation of southeastern Europe, and present a historical example of how coastal populations could have been impacted by future rapid sea-level rise.
A recent CLOUD (Cosmics Leaving OUtdoor Droplets) chamber study showed that sulfuric acid and dimethylamine produce new aerosols very efficiently, and yield particle formation rates that are compatible with boundary layer observations. These previously published new particle formation (NPF) rates are re-analyzed in the present study with an advanced method. The results show that the NPF rates at 1.7 nm are more than a factor of 10 faster than previously published due to earlier approximations in correcting particle measurements made at larger detection threshold. The revised NPF rates agree almost perfectly with calculated rates from a kinetic aerosol model at different sizes (1.7 nm and 4.3 nm mobility diameter). In addition, modeled and measured size distributions show good agreement over a wide range (up to ca. 30 nm). Furthermore, the aerosol model is modified such that evaporation rates for some clusters can be taken into account; these evaporation rates were previously published from a flow tube study. Using this model, the findings from the present study and the flow tube experiment can be brought into good agreement. This confirms that nucleation proceeds at rates that are compatible with collision-controlled (a.k.a. kinetically-controlled) new particle formation for the conditions during the CLOUD7 experiment (278 K, 38% RH, sulfuric acid concentration between 1×106 and 3×107 cm-3 and dimethylamine mixing ratio of ~40 pptv). Finally, the simulation of atmospheric new particle formation reveals that even tiny mixing ratios of dimethylamine (0.1 pptv) yield NPF rates that could explain significant boundary layer particle formation. This highlights the need for improved speciation and quantification techniques for atmospheric gas-phase amine measurements.
A recent CLOUD (Cosmics Leaving OUtdoor Droplets) chamber study showed that sulfuric acid and dimethylamine produce new aerosols very efficiently and yield particle formation rates that are compatible with boundary layer observations. These previously published new particle formation (NPF) rates are reanalyzed in the present study with an advanced method. The results show that the NPF rates at 1.7 nm are more than a factor of 10 faster than previously published due to earlier approximations in correcting particle measurements made at a larger detection threshold. The revised NPF rates agree almost perfectly with calculated rates from a kinetic aerosol model at different sizes (1.7 and 4.3 nm mobility diameter). In addition, modeled and measured size distributions show good agreement over a wide range of sizes (up to ca. 30 nm). Furthermore, the aerosol model is modified such that evaporation rates for some clusters can be taken into account; these evaporation rates were previously published from a flow tube study. Using this model, the findings from the present study and the flow tube experiment can be brought into good agreement for the high base-to-acid ratios (∼ 100) relevant for this study. This confirms that nucleation proceeds at rates that are compatible with collision-controlled (a.k.a. kinetically controlled) NPF for the conditions during the CLOUD7 experiment (278 K, 38 % relative humidity, sulfuric acid concentration between 1 × 106 and 3 × 107 cm−3, and dimethylamine mixing ratio of ∼ 40 pptv, i.e., 1 × 109 cm−3).
Chlorine and bromine atoms can lead to catalytic destruction of ozone in the stratosphere. Therefore the use and production of ozone depleting substances (ODS) containing chlorine and bromine is regulated by the Montreal Protocol to protect the ozone layer. Equivalent Effective Stratospheric Chlorine (EESC) has been adapted as an appropriate metric to describe the combined effects of chlorine and bromine released from halocarbons on stratospheric ozone. Here we revisit the concept of calculating EESC. We derive a new formulation of EESC based on an advanced concept of ODS propagation into the stratosphere and reactive halogen release. A new transit time distribution is introduced in which the age spectrum for an inert tracer is weighted with the release function for inorganic halogen from the source gases. This distribution is termed the “release time distribution”. The improved formulation shows that EESC levels in the year 1980 for the mid latitude lower stratosphere were significantly lower than previously calculated. 1980 marks the year commonly defined as the onset of anthropogenic ozone depletion in the stratosphere. Assuming that the EESC value must return to the same level in order for ozone to fully recover, we show that it will take more than 10 years longer than currently assumed in this region of the stratosphere. Based on the improved formulation, EESC level at mid-latitudes will reach this landmark only in 2060. We also present a range of sensitivity studies to investigate the effect of changes and uncertainties in the fractional release factors and in the assumptions on the shape of the release time distributions. We conclude that, under the assumptions that all other atmospheric parameters like stratospheric dynamics and chemistry are unchanged, the recovery of mid latitude stratospheric ozone would be expected to be delayed by about a 10 years, in a similar way as EESC.
Chlorine and bromine atoms lead to catalytic depletion of ozone in the stratosphere. Therefore the use and production of ozone-depleting substances (ODSs) containing chlorine and bromine is regulated by the Montreal Protocol to protect the ozone layer. Equivalent effective stratospheric chlorine (EESC) has been adopted as an appropriate metric to describe the combined effects of chlorine and bromine released from halocarbons on stratospheric ozone. Here we revisit the concept of calculating EESC. We derive a refined formulation of EESC based on an advanced concept of ODS propagation into the stratosphere and reactive halogen release. A new transit time distribution is introduced in which the age spectrum for an inert tracer is weighted with the release function for inorganic halogen from the source gases. This distribution is termed the release time distribution. We show that a much better agreement with inorganic halogen loading from the chemistry transport model TOMCAT is achieved compared with using the current formulation. The refined formulation shows EESC levels in the year 1980 for the mid-latitude lower stratosphere, which are significantly lower than previously calculated. The year 1980 is commonly used as a benchmark to which EESC must return in order to reach significant progress towards halogen and ozone recovery. Assuming that – under otherwise unchanged conditions – the EESC value must return to the same level in order for ozone to fully recover, we show that it will take more than 10 years longer than estimated in this region of the stratosphere with the current method for calculation of EESC. We also present a range of sensitivity studies to investigate the effect of changes and uncertainties in the fractional release factors and in the assumptions on the shape of the release time distributions. We further discuss the value of EESC as a proxy for future evolution of inorganic halogen loading under changing atmospheric dynamics using simulations from the EMAC model. We show that while the expected changes in stratospheric transport lead to significant differences between EESC and modelled inorganic halogen loading at constant mean age, EESC is a reasonable proxy for modelled inorganic halogen on a constant pressure level.
Convection-permitting models (CPMs) have proven their usefulness in representing precipitation on a sub-daily scale. However, investigations on sub-hourly scales are still lacking, even though these are the scales for which showers exhibit the most variability. A Lagrangian approach is implemented here to evaluate the representation of showers in a CPM, using the limited-area climate model COSMO-CLM. This approach consists of tracking 5‑min precipitation fields to retrieve different features of showers (e.g., temporal pattern, horizontal speed, lifetime). In total, 312 cases are simulated at a resolution of 0.01 ° over Central Germany, and among these cases, 78 are evaluated against a radar dataset. The model is able to represent most observed features for different types of convective cells. In addition, the CPM reproduced well the observed relationship between the precipitation characteristics and temperature indicating that the COSMO-CLM model is sophisticated enough to represent the climatological features of showers.
Der Beitrag analysiert Ungleichheitseffekte des 2007 eingeführten Elterngelds. Wir zeigen, dass die familienpolitische Einführung der Ressource Elterngeld die Einkommensungleichheiten der Produktions- bzw. Erwerbssphäre auf die Reproduktions- bzw. Familiensphäre übertragen hat. Das Elterngeld trägt damit aber zumindest bislang nicht (wie angedacht) zur Aufhebung der asymmetrischen Aufteilung von (entlohnter) Erwerbsarbeit und (nicht-entlohnter) Sorgearbeit zwischen Elternteilen bei. Stattdessen verdeutlicht unsere räumlich orientierte Untersuchung des Elterngeldbezugs ungleiche Muster in den Bewältigungsmöglichkeiten kinderbezogener Sorgearbeiten. Die an der ungleichen Geographie des Elterngelds deutlich werdende Ausdifferenzierung von Bearbeitungschancen von Elternschaft interpretieren wir als Ausdruck von sozialen Spaltungstendenzen auf dem Gebiet der Reproduktion, die von der familienpolitischen Einführung des Elterngelds forciert worden sind.
Mit spitzer Feder beschreibt Lucius Burckhardt in seinem Aufsatz "Wer plant die Planung?" die konfligierenden Rationalitäten der am Planungsprozess beteiligten Akteure. Dabei zeigt er auf, wie "das Kräfteparallelogramm zwischen der regierenden Beamtenschaft, der Bauspekulation, der Bürgerschaft und den durch die beschlossenen Maßnahmen betroffenen Leute" (S. 107) die "Übelstände der Stadt" häufig verschlimmbessert. Es fehle ein "strategisches Vorgehen", das "dem Systemcharakter der Stadt angemessen" (S. 113) wäre.
The assessment of water balance components using global hydrological models is subject to climate forcing uncertainty as well as to an increasing intensity of human water use within the 20th century. The uncertainty of five state-of-the-art climate forcings and the resulting range of cell runoff that is simulated by the global hydrological model WaterGAP is presented. On the global land surface, about 62 % of precipitation evapotranspires, whereas 38 % discharges into oceans and inland sinks. During 1971–2000, evapotranspiration due to human water use amounted to almost 1 % of precipitation, while this anthropogenic water flow increased by a factor of approximately 5 between 1901 and 2010. Deviation of estimated global discharge from the ensemble mean due to climate forcing uncertainty is approximately 4 %. Precipitation uncertainty is the most important reason for the uncertainty of discharge and evapotranspiration, followed by shortwave downward radiation. At continental levels, deviations of water balance components due to uncertain climate forcing are higher, with the highest discharge deviations occurring for river discharge in Africa (−6 to 11 % from the ensemble mean). Uncertain climate forcings also affect the estimation of irrigation water use and thus the estimated human impact of river discharge. The uncertainty range of global irrigation water consumption amounts to approximately 50 % of the global sum of water consumption in the other water use sector.
Evaluation of radiation components in a global freshwater model with station-based observations
(2016)
In many hydrological models, the amount of evapotranspired water is calculated using the potential evapotranspiration (PET) approach. The main driver of several PET approaches is net radiation, whose downward components are usually obtained from meteorological input data, whereas the upward components are calculated by the model itself. Thus, uncertainties can be large due to both the input data and model assumptions. In this study, we compare the radiation components of the WaterGAP Global Hydrology Model, driven by two meteorological input datasets and two radiation setups from ERA-Interim reanalysis. We assess the performance with respect to monthly observations provided by the Baseline Surface Radiation Network (BSRN) and the Global Energy Balance Archive (GEBA). The assessment is done for the global land area and specifically for energy/water limited regions. The results indicate that there is no optimal radiation input throughout the model variants, but standard meteorological input datasets perform better than those directly obtained by ERA-Interim reanalysis for the key variable net radiation. The low number of observations for some radiation components, as well as the scale mismatch between station observations and 0.5° × 0.5° grid cell size, limits the assessment.
The Earth's future depends on how we manage the manifold risks of climate change (CC). It is state-of-the-art to assume that risk reduction requires participatory management involving a broad range of stakeholders and scientists. However, there is still little knowledge about the optimal design of participatory climate change risk management processes (PRMPs), in particular with respect to considering the multitude of substantial uncertainties that are relevant for PRMPs. To support the many local to regional PRMPs that are necessary for a successful global-scale reduction of CC risks, we present a roadmap for designing such transdisciplinary knowledge integration processes. The roadmap suggests ways in which uncertainties can be comprehensively addressed within a PRMP. We discuss the concept of CC risks and their management and propose an uncertainty framework that distinguishes epistemic, ontological, and linguistic uncertainty as well as ambiguity. Uncertainties relevant for CC risk management are identified. Communicative and modeling methods that support social learning as well as the development of risk management strategies are proposed for each of six phases of a PRMP. Finally, we recommend how to evaluate PRMPs as such evaluations and their publication are paramount for achieving a reduction of CC risks.
Aufbauend auf den Erfahrungen zweier Workshops zu (urbaner) Austerität in Griechenland und Deutschland diskutiert der Beitrag die (unterschiedliche) Geschichte und Geographie der Austerität mit besonderem Blick auf die Regionen Frankfurt/Rhein-Main und Athen. Die Erfahrungen der multiplen Krise seit 2008, die sich in Griechenland vor dem Hintergrund einer austeritätspolitischen "Shock Doctrine" und in der BRD im Kontext eines langfristigen Projekts der "scheibchenweisen" Austerität entwickelten, eröffnen dabei die Möglichkeit, die Debatten um urbane Austerität einem kritischen Blick zu unterziehen. Der Beitrag sieht insbesondere im Bereich der Krisen der (urbanen) sozialen Reproduktion sowie der Krisen der (städtischen) Politik und Repräsentation weiteren Forschungsbedarf.
When assessing global water resources with hydrological models, it is essential to know the methodological uncertainties in the water resources estimates. The study presented here quantifies effects of the uncertainty in the spatial and temporal patterns of meteorological variables on water balance components at the global, continental and grid cell scale by forcing the global hydrological model WaterGAP 2.2 (ISI-MIP 2.1) with five state-of-the-art climate forcing input data-sets. While global precipitation over land during 1971–2000 varies between 103 500 and 111 000 km3 yr−1, global river discharge varies between 39 200 and 42 200 km3 yr−1. Temporal trends of global wa- ter balance components are strongly affected by the uncertainty in the climate forcing (except human water abstractions), and there is a need for temporal homogenization of climate forcings (in particular WFD/WFDEI). On about 10–20 % of the global land area, change of river discharge between two consecutive 30 year periods was driven more strongly by changes of human water use including dam construction than by changes in precipitation. This number increases towards the end of the 20th century due to intensified human water use and dam construction. The calibration approach of WaterGAP against observed long-term average river discharge reduces the impact of climate forcing uncertainty on estimated river discharge significantly. Different homgeneous climate forcings lead to a variation of Q of only 1.6 % for the 54 % of global land area that are constrained by discharge observations, while estimated renewable water resources in the remaining uncalibrated regions vary by 18.5 %. Uncertainties are especially high in Southeast Asia where Global Runoff Data Centre (GRDC) data availability is very sparse. By sharing already available discharge data, or installing new streamflow gauging stations in such regions, water balance uncertainties could be reduced which would lead to an improved assessment of the world’s water resources.
Influence of sea surface roughness length parameterization on Mistral and Tramontane simulations
(2016)
The Mistral and Tramontane are mesoscale winds in southern France and above the Western Mediterranean Sea. They are phenomena well suited for studying channeling effects as well as atmosphere–land/ocean processes. This sensitivity study deals with the influence of the sea surface roughness length parameterizations on simulated Mistral and Tramontane wind speed and wind direction. Several simulations with the regional climate model COSMO-CLM were performed for the year 2005 with varying values for the Charnock parameter α. Above the western Mediterranean area, the simulated wind speed and wind direction pattern on Mistral days changes depending on the parameterization used. Higher values of α lead to lower simulated wind speeds. In areas, where the simulated wind speed does not change much, a counterclockwise rotation of the simulated wind direction is observed.
When assessing global water resources with hydrological models, it is essential to know about methodological uncertainties. The values of simulated water balance components may vary due to different spatial and temporal aggregations, reference periods, and applied climate forcings, as well as due to the consideration of human water use, or the lack thereof. We analyzed these variations over the period 1901–2010 by forcing the global hydrological model WaterGAP 2.2 (ISIMIP2a) with five state-of-the-art climate data sets, including a homogenized version of the concatenated WFD/WFDEI data set. Absolute values and temporal variations of global water balance components are strongly affected by the uncertainty in the climate forcing, and no temporal trends of the global water balance components are detected for the four homogeneous climate forcings considered (except for human water abstractions). The calibration of WaterGAP against observed long-term average river discharge Q significantly reduces the impact of climate forcing uncertainty on estimated Q and renewable water resources. For the homogeneous forcings, Q of the calibrated and non-calibrated regions of the globe varies by 1.6 and 18.5 %, respectively, for 1971–2000. On the continental scale, most differences for long-term average precipitation P and Q estimates occur in Africa and, due to snow undercatch of rain gauges, also in the data-rich continents Europe and North America. Variations of Q at the grid-cell scale are large, except in a few grid cells upstream and downstream of calibration stations, with an average variation of 37 and 74 % among the four homogeneous forcings in calibrated and non-calibrated regions, respectively. Considering only the forcings GSWP3 and WFDEI_hom, i.e., excluding the forcing without undercatch correction (PGFv2.1) and the one with a much lower shortwave downward radiation SWD than the others (WFD), Q variations are reduced to 16 and 31 % in calibrated and non-calibrated regions, respectively. These simulation results support the need for extended Q measurements and data sharing for better constraining global water balance assessments. Over the 20th century, the human footprint on natural water resources has become larger. For 11–18% of the global land area, the change of Q between 1941–1970 and 1971–2000 was driven more strongly by change of human water use including dam construction than by change in precipitation, while this was true for only 9–13 % of the land area from 1911–1940 to 1941–1970.
Mistral and tramontane wind speed and wind direction patterns in regional climate simulations
(2016)
The Mistral and Tramontane are important wind phenomena that occur over southern France and the northwestern Mediterranean Sea. Both winds travel through constricting valleys before flowing out towards the Mediterranean Sea. The Mistral and Tramontane are thus interesting phenomena, and represent an opportunity to study channeling effects, as well as the interactions between the atmosphere and land/ocean surfaces. This study investigates Mistral and Tramontane simulations using five regional climate models with grid spacing of about 50 km and smaller. All simulations are driven by ERA-Interim reanalysis data. Spatial patterns of surface wind, as well as wind development and error propagation along the wind tracks from inland France to offshore during Mistral and Tramontane events, are presented and discussed. To disentangle the results from large-scale error sources in Mistral and Tramontane simulations, only days with well simulated large-scale sea level pressure field patterns are evaluated. Comparisons with the observations show that the large-scale pressure patterns are well simulated by the considered models, but the orographic modifications to the wind systems are not well simulated by the coarse-grid simulations (with a grid spacing of about 50 km), and are reproduced slightly better by the higher resolution simulations. On days with Mistral and/or Tramontane events, most simulations underestimate (by 13 % on average) the wind speed over the Mediterranean Sea. This effect is strongest at the lateral borders of the main flow—the flow width is underestimated. All simulations of this study show a clockwise wind direction bias over the sea during Mistral and Tramontane events. Simulations with smaller grid spacing show smaller biases than their coarse-grid counterparts.