Das Projekt "European Sub-Polar Oceans Project, ESOP-2" wird vom Umweltbundesamt gefördert und von Universität Hamburg, Zentrum für Meeres- und Klimaforschung, Institut für Meereskunde (IfM) durchgeführt. The goal of the ESOP-II project, funded by the European Unions MAST III programme, is to understand the thermohaline circulation in the Greenland Sea, its sensitivity, and impact on global ocean circulation, building on an unique combination of novel experimental techniques, modelling and experience, gained under ESOP-1. The project is a consortium of scientists from 21 laboratories in 8 European countries (D, DK, F, Iceland, I, N, UK, S). The focus of ESOP-2 is to study the formation of deep water in the Greenland sea, one of the most active regions in the world's oceans for this process. Deep water formation in the Nordic Seas drives the global 'Conveyor-belt', that is recognized to be relevant to climate and climate change.
Das Projekt "SOLEIL: Solar variability and trend effects in layers and trace gasesin the upper atmosphere" wird vom Umweltbundesamt gefördert und von Leibniz-Institut für Atmosphärenphysik e.V. an der Universität Rostock durchgeführt. In der wissenschaftlichen Klimadiskussion steht der Einfluss des Anstiegs anthropogener Treibhausgase auf die globale Änderung unserer Atmosphäre in den untersten Kilometern im Vordergrund. Allerdings ist die bisher eingetretene mittlere globale Temperaturerhöhung mit 0.85 K von 1880 bis 2012, dies entspricht 0.06 K pro Dekade, jedoch klein. In der Atmosphäre oberhalb von etwa 8 km kehrt sich das Vorzeichen des Treibhauseffekts um: ein Anstieg der Konzentration von infrarot-aktiven Gasen führt zu einer Abkühlung durch eine gesteigerte Emission von Strahlung in den Weltraum. Die globale Veränderung der Atmosphäre findet besonders stark in einem Höhenbereich von 50-75 km statt. Antworten auf die Fragen nach den Ursachen für diese rapiden Änderungen in der mittleren Atmosphäre können uns nur numerische Atmosphärenmodelle (z.B. LIMA) geben. Letztere zeigen, dass die Strahlungsbilanz der mittleren Atmosphäre weitgehend bestimmt wird durch die Spurengase CO2 und O3. Die multivariate Trendanalyse erlaubt nun eine Aussage über den Beitrag am Gesamttrend der einzelnen Spurengase O3 und CO2. Die Spurengase CO2 und O3 tragen jeweils 2/3 bzw. 1/3 zum Trend bei. Die größten Trends liegen im Drucksystem mit 1.3 K/Dekade bei ca. 60 km, während auf geometrischen Höhen der Kontraktionseffekt der Atmosphäre die maximalen Trends auf bis zu 1.8 K/Dekade bei 70 km verstärkt. In den Höhen 80-90 km sind die Trendwerte am kleinsten und können sogar das Vorzeichen wechseln. Dieses Verhalten ist bedingt durch die sehr niedrigen Absoluttemperaturen in 80-90 km Höhe, die sehr empfindlich auf Variationen in den Strahlungsflüssen aus der Stratopausenregion reagieren. Weiterhin konnte in 'SOLEIL' gezeigt werden, dass Temperaturtrends zeitlich variabel sind. So zeigen im Teilzeitraum 1980-1996 die Temperaturen ihren stärksten Abfall aufgrund der Ozonabnahme: die Temperaturtrends können Werte bis zu 4 K pro Dekade erreichen. Im Zeitraum 1995-2009 sind die Durchschnittstemperaturen nahezu unverändert, weil sich hier das stratosphärische Ozon wieder aufbaut ('ozone recovery'). Diese Phasen starker und schwacher Abkühlung zwischen 1961 bis 2008 sind konsistent mit abgeleiteten Temperaturtrends aus französischen Lidarbeobachtungen und Phasenhöhenmessungen am Institut für Atmosphärenphysik (IAP) Kühlungsborn. Der Höhenbereich 80-90 km ist auch die Region, in der Eiswolken seit mehr als 100 Jahren beobachtet werden. Diese Eiswolken (NLC/PMC) existieren in der Sommermesopausenregion polwärts ab 50°N und können sich nur unter sehr kalten Temperaturen unterhalb von etwa 150 K ausbilden. Obwohl der Wasserdampfgehalt in der Mesopausenregion mit 1-7 ppmv sehr gering ausfällt, ist diese Feuchtekonzentration ausreichend für die Bildung von Eisteilchen. Die Nukleation und das Wachstum dieser Eispartikel reagiert sehr empfindlich auf Änderungen der Temperatur und des Wasserdampfes. Aus diesem Grund werden NLC/PMC auf ihre Rolle als potentieller Indikator für Klimaänderungen der globalen Atmosph
Das Projekt "On mechanisms of calving from Antarctic ice shelves" wird vom Umweltbundesamt gefördert und von Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Fachbereich Maschinenbau und Verfahrenstechnik durchgeführt. This project aims to investigate the mechanisms of calving of tabular icebergs from Antarctic ice shelves. Calving is the final consequence of a fracture propagating through an ice shelf, which also behaves as a viscous material. Thus we will apply ice flow dynamical concepts in conjunction with fracture mechanical approaches. Theoretical investigations and numerical simulations lead to a formulation and determination of calving rates. Therefore, two and three dimensional finite element models will be developed, with which sensitivity studies and prognostic simulations will be carried out. The dependency of the mechanisms, and thus the calving rate, on typical geometrical setups, external forcing and material parameters is evaluated. Calving rates are crucial for the evolution of the position of the ice front. The knowledge of appropriate calving rates is required to predict the changes of the extent of the Antarctic ice sheet.
Das Projekt "Sensitivity of Quaternary West Antarctic Ice Sheet advances and retreats in Pine Island Bay" wird vom Umweltbundesamt gefördert und von Stiftung Alfred-Wegener-Institut für Polar- und Meeresforschung e.V. in der Helmholtz-Gemeinschaft (AWI) durchgeführt.
Das Projekt "How is the Brewer-Dobson circulation affected by climate change, and which processes are relevant? (SHARP-BDC)" wird vom Umweltbundesamt gefördert und von Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Institut für Physik der Atmosphäre, Abteilung Dynamik der mittleren Atmosphäre durchgeführt. This project aims to identify and quantify dynamical, physical and chemical processes as well as feedback effects affecting the stratospheric circulation (Brewer-Dobson circulation, BDC), which is responsible for transport of stratospheric air masses from tropical to higher latitudes. Climate change is expected to modify the motion and mass exchange rates of air within the stratosphere and therefore the residence time and distribution of chemical substances. Although substantial progress has been achieved in recent years regarding understanding relevant processes affecting the Brewer-Dobson circulation, there are still open issues about atmospheric processes and feedbacks impacting the long-term changes of the BDC. So far, common analyses of observations and results from numerical model simulations do not indicate a consistent picture. Therefore, multi-decadal transient simulations with Atmospheric General Circulation Models, climate models and Chemistry-Climate Models together with assembled, consistent long-term observations (especially derived from space-borne-, balloon-, aircraft- and ground-based instruments) will be further used to investigate atmospheric processes affecting the BDC. Supplementary numerical sensitivity studies with the different models will be performed and interpreted to establish cause and effect relationships. It will be investigated how the relevant processes are going to alter in a changing climate, modifying stratospheric dynamics.
Das Projekt "How is the stratosphere-troposphere coupling affected by climate change, and how strong is the climate feedback? (SHARP-STC)" wird vom Umweltbundesamt gefördert und von Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Institut für Physik der Atmosphäre, Abteilung Dynamik der mittleren Atmosphäre durchgeführt. The focus of this project is to determine the role of the interaction between the stratosphere and troposphere in a changing climate, in particular to assess the impact of a changing stratosphere on the troposphere- surface system. Observations and model studies have shown that the troposphere and stratosphere influence each other on different time scales, but the mechanisms responsible are not well understood. Questions that will be addressed also in Phase II of this project are if the importance of the coupling between the stratosphere and the troposphere will change in a changing climate and what the consequences will be for surface climate and weather. Transient simulations of the past and future as well as complementary sensitivity simulations with state-of-the-art Chemistry-Climate models (CCMs) will be performed and analysed to study how well current models are able to reproduce the observed coupling, to understand the responsible mechanisms, and to predict its future evolution. New aspects in Phase II are the extension of our studies to the effects of radiative and chemical coupling processes on the troposphere-surface system. The relevance of additional climate feedback processes associated with ocean coupling will be addressed by applying a CCM with an interactive ocean model. The role of the representation of stratospheric processes for stratosphere-troposphere coupling will be studied in simulations with an Earth System Model (ESM) with different spatial resolutions.
Das Projekt "Sensitivity and Adaptation of Forests in Europe under Global Change (SAFE)" wird vom Umweltbundesamt gefördert und von Potsdam-Institut für Klimafolgenforschung e.V. durchgeführt. This project is concerned with the possible impact of global change on forest and forestry in Europe. The main goal is to assess the nature and extent of possible impacts of global change, concentrating on growth and species composition of forests, the economy of the forest industry, and secondary values of forests. These issues shall be addressed at three different scales and at different levels of detail: the European, the German and the regional scale. The SAFE project implementation includes the following tasks: 1. Development of an improved forest model for assessing the ecological impacts of global change, including a submodel for forest management; 2. Development of models of timber production and socio-economic consequences; 3. Establishment of databases on climate, climatic change scenarios and current forest conditions; 4. Model validation for each of the three scales; 5. Integrated impact assessment for the forest sector at each scale.
Das Projekt "Stratospheric ozone: halogen impacts in a varying atmosphere (SHIVA)" wird vom Umweltbundesamt gefördert und von Universität Heidelberg, Institut für Umweltphysik durchgeführt. Objective: SHIVA aims to reduce uncertainties in present and future stratospheric halogen loading and ozone depletion resulting from climate feedbacks between emissions and transport of ozone depleting substances (ODS). Of particular relevance will be studies of short and very short-lived substances (VSLS) with climate-sensitive natural emissions. We will perform field studies of ODS production, emission and transport in understudied, but critical, regions of the tropics using ship, aircraft and ground-based instrumentation. We will parameterize potential climate sensitivities of emissions based on inter-dependencies derived from our own field studies, and surveys of ongoing work in this area. We will study the chemical transformation of ODS during transport from the surface to the tropical tropopause layer (TTL), and in the stratosphere, using a combination of aircraft and balloon observations together with process-oriented meso-scale modelling. These investigations will be corroborated by space-based remote sensing of marine phytoplankton biomass as a possible proxy for the ocean-atmosphere flux of ODS. From this a systematic emission inventory of VSLS ODS will be established to allow construction of future-climate scenarios. The impact of climate-sensitive feedbacks between transport and the delivery of ODS to the stratosphere, and their lifetime within it, will be studied using tracer observations and modelling. Further global modelling will assess the contribution of all ODS, including VSLS (which have hitherto normally been excluded from such models) to past, present and future ozone loss. Here, the sensitivity of natural ODS emissions to climate change parameters will be used in combination with standard IPCC climate model scenarios in order to drive measurement-calibrated chemical transport model (CTM) simulations for present and future stratospheric ozone; to better predict the rate, timing and climate-sensitivity of ozone-layer recovery.
Das Projekt "Forest Ecosystems: Vulnerability Assessment of Goods and Services (ForEVAS)" wird vom Umweltbundesamt gefördert und von Potsdam-Institut für Klimafolgenforschung e.V. durchgeführt. The overall aim of the project ForEVAS is the evaluation of the exposure and sensitivity of goods and services provided by the forest sector to global change, the analysis of the adaptation capacity of forestry to future global change and the role of forestry in mitigation and adaptation strategies at regional scales. The demand for forest goods and services is determined by a wide array of user groups (as forest owners, ground water administration, general public seeking recreation, consumers of wood and fibre products, groups interested in nature conservation). At the same time the object of climate impact, i.e. the forests with a given species-composition and structure, are the result of landscape and forest management measures. Therefore, the capacity for adaptation to climate change has to be described in the context of a multi-purpose, multi-user setting. ForEVAS will analyse vulnerability based on indicators, criteria and decisions on demand and preferred management options that are assessed in a dialogue with user groups. To do this, methods of scenario analyses with simulation models, of multi-criteria analysis, and uncertainty analysis of decision making with regard to the adaptive measures will be applied.
Das Projekt "ATMOCHEM - Integrated analysis of long-range pollution transport to mid- and high-latitudes over Europe using model simulations, satellite observations, and aircraft measurements (INTAS)" wird vom Umweltbundesamt gefördert und von Universität Bremen, Institut für Umweltphysik durchgeführt. In this project, satellite observations of nitrogen dioxide in the atmosphere have been used to investigate the occurrence of long range transport of pollution over the oceans. Such export of pollution is important as it affects air quality in clean regions, changes background levels of pollutants in large parts of the world and is relevant for international conventions such as LRTAP. Nitrogen dioxide is a tracer of pollution which is mainly produced in the combustion of fossil fuels but also by biomass burning and lightning. As the atmospheric lifetime of NO2 is short, long range transport is only possible at high wind speed, preferably at low solar irradiation (mid and high latitudes in fall and winter). In standard satellite products of tropospheric NO2 there is little evidence for long range transport. This is due to the fact that such transport is often linked to the presence of clouds, and cloudy data is usually excluded from the satellite data sets as in such cases, the instrument does not have an unobstructed view to the surface where most of the pollution is located. Therefore, in this study all NO2 data from the European GOME-2 satellite instrument have been used and a simplified treatment of the effect of clouds on the detection sensitivity has been developed. It assumes that in long range transport events in the presence of clouds, the NO2 is well mixed within the cloud. This assumption is supported by some case studies on CO measurements in the atmosphere and NO2 data from atmospheric models. Using measurements from several days, long range transport events can be identified in the satellite data using image processing techniques and the assumptions that a) NO2 plumes from transport are short lived and can therefore be identified by evaluating deviations from the mean values and b) that they are contiguous in space and c) that they can be traced back to regions with elevated NO2 values. An algorithm based on these principles has been developed and implemented, and a multi-annual data set of GOME-2 measurements has been evaluated, identifying nearly 4000 individual NO2 transport events over oceans. Using this data set, a statistical evaluation of NO2 long range transport events could be performed. The results show, that the main regions affected by NO2 from long range transport are between the US and Europe, in the outflow of China and East of South America and South Africa. In all regions, most events are observed in fall and winter. For Europe and China, mainly short lived events are observed as NO2 plumes are often rapidly transported back over the continent where they cannot be detected by the algorithm. While from South Africa and the Eastern US many well defined transport events can be traced in the satellite data, the quantitative NO2 export is largest from China, followed by Europe. In total, an NO2 outflow of 50 GgN/a is computed for the four main NO2 export regions which is small in comparison to total NOx emissions but sign
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