Das Projekt "Erweiterte experimentelle Untersuchungen der reaktiven Halogenchemie in Polarregionen (HALOPOLE III)" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Universität Heidelberg, Institut für Umweltphysik.Halogenradikale spielen eine Schlüsselrolle in der Chemie der polaren Grenzschicht. Alljährlich im Frühjahr beobachtet man riesige Flächen von mehreren Millionen Quadratkilometern mit stark erhöhten Konzentrationen von reaktivem Brom, welches von salzhaltigen Oberflächen in der Arktis und Antarktis emittiert werden. Dieses Phänomen ist auch als Bromexplosion bekannt. Des Weiteren detektieren sowohl boden- als auch satellitengestützte Messungen signifikante Mengen von Jodoxid über der Antarktis, jedoch nicht in der Arktis. Die Gründe für diese Asymmetrie sind nach wie vor unbekannt, aber das Vorhandensein von nur wenigen ppt reaktiven Jods in der antarktischen Grenzschicht sollte einen signifikanten Einfluss auf das chemische Gleichgewicht der Atmosphäre haben und zu einer Verstärkung des durch Brom katalysierten Ozonabbaus im polaren Frühjahr haben. Der Schwerpunkt der Aktivitäten im Rahmen von HALOPOLE III wird auf der Untersuchung von wichtigen Fragestellungen liegen, die im Rahmen der Vorgängerprojekte HALOPOLE I und II im Bezug auf die Quellen, Senken und Transformationsprozesse von reaktiven Halogenverbindungen in Polarregionen aufgetreten sind. Basierend sowohl auf der synergistischen Untersuchung der bislang gewonnen Daten aus Langzeit - und Feldmessungen sowie auf neuartigen Messungen in der Antarktis sind die wesentlichen Schwerpunkte: (1) Die Untersuchung einer im Rahmen von HALOPOLE II aufgetretenen eklatanten Diskrepanz zwischen aktiven und passiven Messungen DOAS Messungen von IO. (2) Eine eingehende Analyse der DOAS Langzeitmessungen von der Neumayer Station und Arrival Heights (Antarktis) sowie Alert (Kanada) bezüglich Meteorologie, Ursprung der Luftmassen, Vertikalverteilung, sowie des Einflusses von Schnee, Meereis und Eisblumen auf die Freisetzung von reaktiven Halogenverbindungen. (3) Die Untersuchung der kleinskaligen räumlicher und zeitlichen Variation von BrO auf der Basis einer detaillierten Analyse der flugzeuggebundenen MAX-DOAS Messungen während der BROMEX 2012 Kampagne in Barrow/Alaska. (4) Die Analyse der kürzlich in der marginalen Eiszone der Antarktis auf dem Forschungsschiff Polarstern durchgeführten Messungen im Hinblick auf die horizontale und vertikale Verteilung von BrO und IO, sowie den Einfluss der Halogenchemie auf den Ozon- und Quecksilberhaushalt. (5) Weitere detaillierte Untersuchungen des Einflusses von Halogenradikalen, insbesondere Chlor und Jod, auf das chemische Gleichgewicht der polaren Grenzschicht auf der Basis einer Messkampagne in Halley Bay, Antarktis. (6) Detailliertere Langzeit-Messungen von Halogenradikalen und weiteren Substanzen auf der Neumayer Station mittels eines neuen Langpfad-DOAS Instruments welches im Rahmen dieses Projektes entwickelt wird. Zusätzlich zu den bereits existierenden MAX-DOAS Messungen werden diese eine ganzjährige Messungen des vollen Tagesganges sowie die Untersuchung nicht nur der Brom- und Jodchemie, sondern auch der Chlorchemie ermöglichen.
Das Projekt "Quantifizierung sekundärer Eisbildungsmechanismen: das Zersplittern gefrierender Tropfen gegen Tropfen-Eispartikel-Kollision" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Leibniz-Institut für Troposphärenforschung e.V..Eine verlässliche Modellierung der Wolkenprozesse für die Wetter- und Klimavorhersage bedarf eines fundierten Verständnisses der Eisbildung in Mischphasenwolken. Jedoch überschreiten in situ gemessene Eiskristallkonzentrationen oft die Konzentration der eisnukleierenden Partikel um mehrere Größenordnungen. Motiviert durch diese Diskrepanz sucht die Atmosphärenforschungsgemeinschaft nach Sekundären Eisbildungsmechanismen (SIP), d.h. Prozessen, bei denen zusätzliche Eispartikel zum Beispiel durch Fragmentierung vorhandener Eispartikel oder während des Tropfengefrierens gebildet werden.In Zusammenarbeit zwischen dem Leibniz-Institut für Troposphärenforschung (TROPOS) in Leipzig und dem Institut für Meteorologie und Klimaforschung des Karlsruher Institutes für Technologie (KIT) planen wir, zwei mögliche SIP Mechanismen zu untersuchen: die Bildung von sekundären Eispartikeln, verursacht durch (A) Tropfen-Eispartikel Kollisionen (Eissplitterentstehung) und (B) dem Zersplittern gefrierender Tropfen. Es wird angenommen, dass diese zwei SIP Mechanismen in Mischphasenwolken besondere Relevanz besitzen.Folgende Hauptziele wird das geplante Projekt umfassen: (1) die Entwicklung eines neuen experimentellen Aufbaus (Ice Droplet splintEring and FragmentatIon eXperiment, IDEFIX), um die Bildung sekundärer Eispartikel durch (A) und (B) zu untersuchen, (2) die Identifizierung des physikalischen Mechanismus der sekundären Eisbildung mittels Hochgeschwindigkeitsvideoüberwachung eines SIP Ereignisses, (3) die Quantifizierung der Anzahl sekundärer Eispartikel in Abhängigkeit von der Temperatur, Tropfengröße und Aufprallgeschwindigkeit (A) und von der Tropfengröße und -zusammensetzung (B), und (4) die Entwicklung von Parametrisierungen beider SIP Mechanismen (A) und (B). Diese Parametrisierungen werden von externen Kooperationspartnern in Modellen, die Wolkenmikrophysik auflösen, für die Beschreibung der SIP Mechanismen angewendet.Bei der Entwicklung von IDEFIX werden wir von der langjährigen Erfahrung beider Kooperationspartner profitieren: die Expertise des TROPOS Teams bzgl. der Tropfen-/Eisbildung und des Tropfen-/Eispartikelwachstums und Verdunstung in einem wohl definierten thermodynamisch kontrollierten System, sowie der Detektion dieser Hydrometeore, und der Expertise des KIT Teams für die Hochgeschwindigkeitsvideobeobachtung von freischwebenden gefrierenden Tropfen. Das modulare Design von IDEFIX ermöglicht es beiden Kooperationspartnern ihre Möglichkeiten für die Modulentwicklung vor Ort auszuschöpfen und dann beim Experimentieren in einer Reihe von Messkampagnen, die am TROPOS durchgeführt werden, zusammenzuführen.
Das Projekt "Catchment classification and regionalisation with Self-Organising Maps (SOMs) and flexible model structures" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Universität Trier, Fachbereich VI Raum- und Umweltwissenschaften, Fach Physische Geographie.The major research objective of the project is catchment classification with a view to regionalization. Three different clustering methods serve as a basis for catchment classification: Self Organising Maps (SOMs), a benchmark conceptual model and the SUPERFLEX modelling framework. We will classify catchments by runoff behaviour and by hydroclimatic and physiographic properties. The project will use data from approximately 100 catchments in western Germany. Next, the classification methods will be compared and based on the best classification method we will regionalize runoff and model parameters to test its suitability for regionalization.Catchment classification as well as regionalization will be used to gain insight into the functioning of meso-scale river basins: to uncover resemblances and discrepancies, to interpret their hydrological behaviour and to provide meaningful data-backed-up hypothesis. Furthermore, we will develop auto-mated procedures of our methods and assemble them into a toolbox, which can be used by a wide group of users. This study will strive for a dual approach: firstly, to implement novel clustering methods with a view to regionalization and secondly, to stimulate the ongoing and highly relevant discussion on catchment classification and regionalisation.
Das Projekt "Steady-State Dilution and Mixing-Controlled Reactions in Three-Dimensional Heterogeneous Porous" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Eberhard Karls Universität Tübingen, Zentrum für Angewandte Geowissenschaften (ZAG), Arbeitsgruppe Hydrogeology.Understanding transport of contaminants is fundamental for the management of groundwater re-sources and the implementation of remedial strategies. In particular, mixing processes in saturated porous media play a pivotal role in determining the fate and transport of chemicals released in the subsurface. In fact, many abiotic and biological reactions in contaminated aquifers are limited by the availability of reaction partners. Under steady-state flow and transport conditions, dissolved reactants come into contact only through transverse mixing. In homogeneous porous media, transverse mixing is determined by diffusion and pore-scale dispersion, while in heterogeneous formations these local mixing processes are enhanced. Recent studies investigated the enhancement of transverse mixing due to the presence of heterogeneities in two-dimensional systems. Here, mixing enhancement can solely be attributed to flow focusing within high-permeability inclusions. In the proposed work, we will investigate mixing processes in three dimensions using high-resolution laboratory bench-scale experiments and advanced modeling techniques. The objective of the proposed research is to quantitatively assess how 3-D heterogeneity and anisotropy of hydraulic conductivity affect mixing processes via (i) flow focusing and de-focusing, (ii) increase of the plume surface, (iii) twisting and intertwining of streamlines and (iv) compound-specific diffusive/dispersive properties of the solute species undergoing transport. The results of the experimental and modeling investigation will allow us to identify effective large-scale parameters useful for a correct description of conservative and reactive mixing at field scales allowing to explain discrepancies between field observations, bench-scale experiments and current stochastic theory.
Das Projekt "Discrepancy between long-term trends of the 10Be- and 14C-inferred radionuclide production rate: Likely reasons and implications" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Universität Heidelberg, Institut für Umweltphysik.The atmospheric production rate of cosmogenic radionuclides depends on the variable shielding effects of cosmic rays by the solar activity and the geomagnetic field intensity. The history of these production rate changes can be basically inferred from 14C tree ring/sediment records as well as from 10Be archived in polar ice cores. However, while both reconstruction efforts agree fairly well in view of their decadal to centennial variability, they systematically deviate, for unknown reasons, on the millennia time scale, particularly in the early Holocene and late Glacial. The project aims at pinning down the main reasons for this apparent inconsistency by combining a global carbon cycle model with an atmospheric 10Be cycle model, supported by an air/firn transfer module. This innovative attempt comprises the extension of an existing carbon cycle box model to the simulation of aerosol-borne radionuclides, backed up by novel 10Be and 7Be aerosol data as well as dedicated sensitivity studies. Thereby, the various impacts of non-production related changes on the 14C and 10Be archive data shall be investigated, focusing on possible long term changes, related to the carbon and to the atmospheric 10Be cycles. Final evaluation of the results aims at depicting realistic scenarios, which allow to reduce the reconstruction mismatch, and thus, to improve the understanding of past cosmogenic production rate changes.
Das Projekt "Production and Processing of Atmospheric Aerosols from Biogenic and Biomass Burning Sources" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Paul Scherrer Institut.Aerosols affect climate through direct scattering and/or absorption of solar radiation and by acting as cloud condensation nuclei (CCN). Cloud formation and optical scattering cool the atmosphere, while optical absorption (e.g. by black carbon) warms it. These climate effects are strongly influenced by particle concentration, atmospheric lifetime, CCN activity, and optical properties, which are determined by particle composition. Composition is in turn influenced by the effects of emissions sources and oxidation-induced atmospheric transformations. Quantification of these effects has proven challenging, in part because of major uncertainties resulting from the complexity of the organic aerosol fraction. Recent studies have demonstrated the dominance and ubiquity of secondary organic aerosol (SOA), formed from atmospheric reactions of gas-phase precursors. Biogenic emissions and biomass burning constitute major sources of SOA. Biomass burning is also a major source of black carbon and primary organic aerosol. Deconvolution of aerosol sources and processes is complicated by the simultaneous influence of multiple factors on aerosol composition at field measurement sites, discrepancies between laboratory and field measurements, and limitations in existing measurement and analysis techniques. This project provides a detailed characterization of the chemical and physical properties of biogenic and biomass burning aerosol, and the rate and extent to which these properties change as a result of reaction with the OH radical, a major atmospheric oxidant. The project combines three approaches: (1) OH oxidation of model compounds and well-characterized sources characteristic of biomass burning and biogenic emissions; (2) summer and winter field measurements in locations influenced by these sources; and (3) development and deployment of a flow reactor for controlled OH oxidation of laboratory and ambient sources. Molecular tracers and/or chemical signatures for biogenic and biomass burning SOA will be identified using a newly developed coupled high-resolution time-of-flight mass spectrometer/thermal desorption aerosol gas chromatograph. The flow reactor will provide a controlled environment for ambient aerosol oxidation, thereby enabling process-level analysis of the nature and rate of molecular changes induced by atmospheric oxidation, as well as the effect of such processes on source apportionment techniques commonly applied to ambient aerosol. Optical absorption and scattering properties will be constrained with respect to atmospheric oxidation.
Das Projekt "Support to Member States in improving waste management based on assessment of Member States' performance" wird/wurde gefördert durch: Europäische Kommission, Generaldirektion Umwelt / Kommission der Europäischen Gemeinschaften Brüssel. Es wird/wurde ausgeführt durch: BIPRO Beratungsgesellschaft für integrierte Problemlösungen GmbH.Implementation of EU waste legislation shows large differences in the EU Member States especially with regard to municipal waste management. Major discrepancies prevail particularly in the implementation and application of the Waste Framework Directive and proper transposition of EU requirements into national legislation. The waste management performance of all EU Member States was subject to screening to identify those Member States with the largest implementation gaps, in particular in relation to municipal waste management. For screening the main elements and legal requirements stemming from EU waste directives (mainly from the Waste Framework and the Landfill Directive) were considered for the design of suitable criteria. These core elements comprise the practical implementation of the waste management hierarchy, application of economic and legal instruments to move up the waste hierarchy, sufficiency of treatment infrastructure and quality of waste management planning, the fulfilment of targets and infringement procedures. These elements were assessed by 18 criteria for each Member State taking into account information sources at EU, national or regional level. Latest available statistical data and data of former years for comparison of development within a country were extracted from the EUROSTAT database. References comprised reports published by the European Commission, the European Topic Centre on Sustainable Consumption and Production, internal working documents of EUROSTAT and the EU Commission as well as national/regional Waste Management Plans. Where available also Waste Prevention Programmes were screened. The screening results confirmed the assumption of large differences within the EU-27 with regard to treatment of municipal waste, compliance with the WFD and Landfill Directives and application of legal or economic instruments as well as planning quality. For each criterion two, one or zero points could be achieved, leading to maximum points of 42 for all criteria. The methodology includes weighting of results for three selected criteria related to the application of the treatment options recycling, energy recovery and disposal of municipal waste.
Das Projekt "Quantifying the sensitivity of the hydrological cycle to increasing temperature" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Eidgenössische Technische Hochschule Zürich, Institut für Atmosphäre und Klima.Since the preindustrial period, the concentration of greenhouse gases in the atmosphere is increasing due to human activities. It is well understood that greenhouse gases such as carbon dioxide act to increase the temperature of the atmosphere. Warmer air can consequently hold more moisture, which again results in an increase in precipitation. Global climate models are currently the most powerful tool to investigate the future climate but interestingly, the simulated increase in precipitation is smaller by a factor of two compared to observations. Since changes in precipitation will affect numerous ecosystems as well as food and water security, it is important to understand the reasons for the discrepancy between climate models and observations. On one hand, observations might overestimate the precipitation increase because of too short available time series or inadequacies in measurement systems. On the other hand, climate models might fail at simulating important processes leading to the precipitation formation. In a first step, different observation datasets will be analysed and compared. Then, simulations will be performed with a global climate model in order to investigate the mechanisms leading to precipitation and these results will be compared to already existing model datasets. The proposed project will allow to understand the nature of the discrepancy between climate models and observations. Overall, the project will inform policy makers about the future climate and allow them to agree on adequate adaptation measures.
Das Projekt "Schwerpunktprogramm (SPP) 1158: Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; Bereich Infrastruktur - Antarktisforschung mit vergleichenden Untersuchungen in arktischen Eisgebieten, Overlap and discrepancies between ecotypes, genotypes and morphotypes of Antarctic and Arctic nanofauna" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Universität Köln, Institut für Zoologie, Biozentrum Köln, Arbeitsgruppe Allgemeine Ökologie.
Das Projekt "Evapotranspiration estimates at global and regional scales (WACMOS-II)" wird/wurde gefördert durch: Kommission der Europäischen Gemeinschaften Brüssel. Es wird/wurde ausgeführt durch: Centre National de la Recherche Scientifique, Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres (LERMA).The WACMOS-ET project aims to advance the development of land evaporation estimates at global and regional scales. Its main objective is the derivation, validation and inter-comparison of a group of existing evaporation retrieval algorithms driven by a common forcing data set. With the project coming to an end, here we present for the first time the results of our global simulations. Four commonly used process-based evaporation methodologies are evaluated: the Penman-Monteith algorithm from the official MODIS evaporation product (PM-MOD), the Global Land Evaporation: the Amsterdam Methodology (GLEAM), the Surface Energy Balance System (SEBS), and the Priestley and Taylor Jet Propulsion Laboratory model (PT-JPL). The resulting global spatiotemporal variability of evaporation, the closure of regional water budgets and the discrete estimation of land evaporation components or sources (i.e. transpiration, interception loss and direct soil evaporation) are investigated using river discharge data, independent global evaporation data sets and results from previous studies. The project carried out an assessment of the performance of these four models, first, at local scales using measurements from eddy-covariance towers and lysimeters. Them, an assessment and inter-comparisons of their performances was done at global level. Results indicate that the Priestley and Taylor based products (PT-JPL and GLEAM) perform overall better for most ecosystems and climate regimes. While all three products adequately represent the expected long-term geographical patterns and temporal seasonality, there is a tendency from PM-MOD to underestimate the flux in the tropics and subtropics. Overall, results from GLEAM and PT-JPL appear more robust when compared against surface water balances from 837 globally-distributed catchments, and against evaporation estimates from ERA-Interim and the Model Tree Ensemble (MTE). Nonetheless, all products manifest large discrepancies during conditions of water stress and drought, and deficiencies in the way evaporation is partitioned into its different components. Overall, the observed inter-product variability implies caution in using a single data set for any large-scale application in isolation. The general finding that different models perform better under different conditions highlights the potential for considering biome- or climate-specific composites of models. Yet, the generation of a multi-product ensemble, with weighting based on validation analyses and uncertainty assessments, appears the best way forward in our long-term goal to develop a robust observational benchmark data set of continental evaporation.
