Das Projekt "The impact of tropical - extratropical interactions on downstream predictability (TROP)" wird vom Umweltbundesamt gefördert und von Deutscher Wetterdienst durchgeführt. In this project we investigate the mechanisms by which organised tropical convective systems, and, in particular, tropical cyclones undergoing extratropical transition (ET), interact with the midlatitude upper-level wave guide. We consider how this interaction influences the dynamics and predictability of the ET system itself, the midlatitude flow, and sub tropical cyclones that may develop downstream. We will use a combined observational, COSMO modelling, and data denial approach applied to the ET cases of the THORPEX Pacific Asian Regional Campaign. Diagnostic techniques, including PV inversion and object-oriented diagnostics will be applied to investigate the interactions between the convective and synoptic-scale flow. We will investigate the impact of different regimes of tropical convection on midlatitude predictability through analysis of Year of Tropical Convection datasets and TIGGE data, conducting experiments with ensemble prediction systems (EPS), and diagnosing the results with ensemble sensitivity analysis and other techniques. Finally, we will investigate the predictability of the structural changes during ET and of sub-tropical cyclogenesis using the multiscale ensemble. The results of this study will be used to define observational strategies for a future THORPEX field campaign.
Das Projekt "Charakterisierung der mit Natriumpyrophosphat löslichen organischen Bodensusbstanz mittels FT-IR" wird vom Umweltbundesamt gefördert und von Leibniz-Zentrum für Agrarlandschaftsforschung (ZALF) e.V., Institut für Bodenlandschaftsforschung durchgeführt. Zusammensetzung und Menge der organischen Bodensubstanz (OBS) werden durch die Landnutzungsform beeinflußt. Die OBS läßt sich nach ihrer Abbaubarkeit und nach ihrer Löslichkeit in verschiedene Pools einteilen. So kann die wasserlösliche organische Bodensubstanz (DOM) als Maßzahl für die abbaubare OBS herangezogen werden. Mit Natriumpyrophosphat-Lösung als Extraktionsmittel läßt sich ein weit größerer Anteil der OBS erfassen, da der stabilisierende Bindungsfaktor zwischen OBS und Bodenmineralen entfernt wird. Extrahiert man zuerst mit Wasser und anschließend mit Natriumpyrophosphat-Lösung, erhält man im letzten Schritt den schwer abbaubaren OBS-Anteil. Über die funktionelle Zusammensetzung der organischen Substanz dieser Pools und deren Abhängigkeit von Landnutzungsformen ist relativ wenig bekannt. Ziel der geplanten Untersuchung ist es, den Pool der löslichen abbaubaren und schwer abbaubaren OBS zu quantifizieren und deren funktionelle Zusammensetzung mittels FT-IR Spektroskopie zu erfassen. Die so gewonnenen Daten sollen der Validierung von Soil Organic Matter Turnover modellen (z.B. Roth 23.6) dienen und die im Modell berechneten Pools um einen qualitativen Term ergänzen. In Zusammenarbeit mit anderen Arbeitsgruppen sollen im DFG-Schwerpunktprogramm 1090: ;Böden als Quelle und Senke für CO2 die Pools der löslichen abbaubaren und schwer schwer löslichen, schwer abbaubaren organischen Bodensubstanz (OBS) quantifiziert, die funktionelle Zusammensetzung dieser Pools mittels FT-IR Spektroskopie erfasst und Abbaubarkeit der erhaltenen Extrakte überprüft werden, um Mechanismen, die zur Stabilisierung der OBS führen, aufzuklären.
Das Projekt "Fire - climate feedback in the Earth System" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Meteorologie durchgeführt. Fires are an integral Earth System process, which is controlled by climate and at the same time impacts climate in multiple ways. As such fires form a feedback mechanism in the Earth System, which might amplify or dampen climate change. At present this feedback is not well understood nor is it represented in current generation Earth System models used to study climate change. The proposed research project aims to quantify the fire-climate feedback by incorporating the integral role of fires into an Earth System Model (ESM). Together with improved observational based process understanding the project will analyze how fires have developed throughout Earth history and how single fire driven processes contribute to the overall fire climate impact. A mechanistic terrestrial biosphere fire model will be implemented into the ESM and fire mediated climate relevant processes will be coupled between the different ESM compartments, including the atmosphere, ocean and cryosphere. This cross-disciplinary research project will foster the understanding of past climate change and will hopefully allow a better assessment of human induced future climate change by further constraining the climate sensitivity of the Earth system.
Das Projekt "Formation of brine channels in sea ice" wird vom Umweltbundesamt gefördert und von Fachhochschule Münster, Fachbereich Physikalische Technik durchgeführt. Within this interdisciplinary project the formation of brine channels in sea ice will be explored. The microscopic properties of sea ice, especially the permeability plays an important role for the energy exchange between ocean and atmosphere and is determined by the brine channel volume. The brine channel structure will be measured by computer tomography and image analysis. We intend to describe the channel structure by two phenomenological models, a morphogenesis approach of Alan Turing in connection with the phase transition theory of Ginzburg and Landau, and the phase field method with respect to the Cahn-Hilliard equation. We solve these nonlinear evolution equations in two and three dimensions and compare the size and texture of the brine channels with the measurements. In addition to the phenomenological equations we support our studies with molecular dynamics simulations and the density functional theory in order to obtain deeper insights at the molecular scale. Comparative first-principles studies will then enhance the trust in the extracted parameters and will lead to classical density functional for the two phases. We will discuss the phase transitions in terms of a phenomenological theory based on microscopic parameters and try to extract the underlying mechanism for the formation of water-ice boundaries. Specifically, we want to explore three theoretical questions: (i) How are ice-water melting fronts moving, (ii) How are brine channels formed and (iii) How do surface properties influence the structure formation of brine channels. The project is based on the experiences of three fields, the theoretical biological physics, chemical physics and the many-body theory. The final aim of the project is to provide input parameters for global climate models.
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 "AURORa - Investigation of the Radar Backscatter of Rain Impinging on the Ocean Surface" wird vom Umweltbundesamt gefördert und von Universität Hamburg, Zentrum für Meeres- und Klimaforschung, Institut für Meereskunde (IfM) durchgeführt. Over land, observations of rain rates are more or less operational. To obtain information about precipitation at the coastal zones, weather radars are used. However, over the oceans, especially away from the main shipping routes, no direct precipitation measurements are performed. In these regions, satellite data can provide information about precipitation events. Satellites deploying passive and active microwave sensors can operate independently of cloud cover and time of day. Passive microwave sensors give crude estimates of rain rates over large areas but cannot resolve small-scale rain events of short duration as are often observed in the tropics, for example. Active microwave sensors with high resolutions, such as synthetic aperture radars can provide more reliable information. Though the effect of rain on the atmosphere is a very topical area of research, the radar backscattering mechanisms at the water surface during rain events combined with wind are still not well understood. The purpose of this project is to investigate the radar backscattering from the water surface in the presence of rain and wind in order to interpret satellite radar data produced by active microwave sensors. Furthermore, the results should be embedded into models of the radar backscattering from the water surface to allow for estimating rain rates by using satellite data. Research topics: Rain impinging on a water surfaces generates splash products including crowns, cavities, stalks and secondary drops, which do not propagate, and ring waves and subsurface turbulence. We are investigating this phenomena at the wind-wave tank of the University of Hamburg. The tank is fitted with an artificial rain simulator of 2.3 m2 area mounted 4.5 m over the water surface. Rain drops of 2.1 and 2.9 mm in diameter with rain rates up to 100 mm/h have been produced. Wind with speeds 10 m/s and monomolecular slicks act on the water surface. The influence of the rain on the water surface is measured with a resistance type wire gauge, a two dimensional laser slope gauge and an coherent 9.8 GHz (x band) continuous wave scatterometer operating at VV-, HH- and HV-polarization. The influence of rain below the water surface is measured with colored raindrops which are observed with a video camera to investigate the turbulent motion and the depth of the mixed layer. At the North Sea Port of Buesum in Germany, a scatterometer operating at all polarizations and five frequencies will be mounted during summer of this year. The radar backscatter of the sea surface during rain events will be measured in combination with meteorological observations. With help of these measurements, existing radar backscatter models of the water surface will be improved for the presence of rain events. To validate the improved models, ERS-2 SAR-images will be compared with weather radar data.
Das Projekt "Design Options for Sectoral Carbon Market Mechanisms and Their Implications for the EU ETS" wird vom Umweltbundesamt gefördert und von Wuppertal Institut für Klima, Umwelt, Energie gGmbH durchgeführt. Die UN-Klimakonferenz in Durban entschied 2011, einen neuen Marktmechanismus (NMM) zu etablieren, der breite Segmente der Volkswirtschaft von Entwicklungsländern adressieren soll. Die detaillierten Modalitäten und Verfahren sind noch zu entwickeln. Das Projekt entwarf verschiedene Designoptionen für den neuen Mechanismus und untersuchte, welche Auswirkungen der NMM in spezfischen Sektoren in spezifischen Entwicklungsländern haben könnte. Drei Designvorschläge für den neuen Marktmechanismus: Die Entwicklung der Designvorschläge basierte auf drei vorrangigen Kriterien: Ökologische Effektivität und Integrität, Möglichkeiten zur Evolution in Richtung eines cap-and-trade Emissionshandelssystems, das mit dem EU-EHS kompatibel ist, und ökonomische Effizienz. Die drei Vorschläge sind: - Government Crediting System: Gemäß diesem Vorschlag würde das Gastgeberland einen sektoralen Emissionsschwellenwert definieren und Politiken und Maßnahmen umsetzen, um Emissionen zu reduzieren. Wenn die Emissionen unter den Schwellenwert reduziert werden, erhält das Gastgeberland Emissionszertifikate, mit denen es die Politikumsetzung (ko-)finanzieren kann. Die Emissionen werden auf aggregierter anstatt auf Anlagenebene abgerechnet. - Handelbarer Emissionsintensitätsstandard: Gemäß diesem Vorschlag wird der sektorale Emissionsschwellenwert auf die einzelnen Anlagen herunter gebrochen. Das heißt, jede Anlage erhält einen eigenen Emissionsschwellenwert. Den Gastgeberländern wird empfohlen, die Anlagenbetreiber verbindlich zum Erreichen der Schwellenwerte zu verpflichten. - Anlagenbasiertes Emissionshandelssystem: In diesem System würde das Gastgeberland ein sektorales Emissionsziel annehmen und entsprechend im Voraus Emissionszertifikate erhalten. Das Land würde ein anlagenbasiertes Emissionshandelssystem für den Sektor einführen, um das Ziel zu erreichen. Fallstudien: Die Fallstudien bestanden darin, den zweiten Vorschlag theoretisch in fünf Sektoren in fünf Entwicklungsländern anzuwenden. Wesentliche Ergebnisse waren: - Vorhersagen zukünftiger Emissionen weisen erhebliche Unterschiede auf. Internationale Standards sind daher nötig, wenn Emissionsschwellenwerte in unterschiedlichen Sektoren und Ländern vergleichbare Anstrengungen zur Generierung von Emissionszertifikaten reflektieren sollen. - Konsistente und verlässliche Emissionsdaten sind zentral für das Design und die Durchführung des NMM. Solche Daten sind jedoch leider nicht immer verfügbar. - Einige Sektoren weisen ein großes ökonomisch nutzbares Emissionsreduktionspotenzial auf. Es ist nötig, zu untersuchen, warum diese Möglichkeiten bisher nicht genutzt worden sind. Dies ist erforderlich, um sicher zu stellen, dass die Anwendung des NMM - und damit die Einführung finanzieller Anreize - tatsächlich Investitionen stimulieren und einen Einfluss auf die Emissionen haben kann. usw.
Das Projekt "Effects of nurse tree species on growth, environment and physiology of underplanted Toona ciliata (F. Muell.)" wird vom Umweltbundesamt gefördert und von Universität Freiburg, Waldbau-Institut durchgeführt. Toona ciliata (Australian red cedar) is highly valued for veneer and furniture production and endangered in its natural ecosystems due to exploitation. This work aims to improve the availability of this wood on the market and help reduce pressure on the species in its native environment. An afforestation project cultivating Toona ciliata was introduced to the study site in Misiones, Argentina. The local cultivation faces losses caused by drought and frost, because T. ciliata requires overstory protection when young. Consequently, Grevillea robusta, Pinus elliottii x Pinus caribaea, and Pinus taeda, nurse tree species which also produce sought-after wood were chosen to provide protection. One-year-old T. ciliata seedlings were planted underneath each of the six-year-old nurse species. An inventory after one year indicated that both survival and height increment were highest underneath G. robusta and lowest underneath P. elliottii x P. caribaea. In this study I am examining possible facilitation and competition mechanisms between the overstory and understory T. ciliata. Extensive empirical data collected over the course of 3 years will be utilized to project potential growth scenarios for several rotations using a computer based forest growth model.
Das Projekt "Tropical High Altitude Clouds and their Impact on Stratospheric Humidity" wird vom Umweltbundesamt gefördert und von Leibniz-Institut für Troposphärenforschung e.V. durchgeführt. Clouds play a key role in the Earth's climate system by regulation of the incoming and outgoing radiation, chemical and dynamical processes. Ice clouds at high altitudes in the tropics, the so called tropical tropopause layer, are particularly important since this is the main region where air ascends slowly from the troposphere into the dry stratosphere. Thus, these ice clouds affect the stratospheric water vapour content which in itself is a main driver of radiative and chemical processes, e.g. ozone depletion, there. These clouds can either be of convective nature, or occur in convective overshooting cloud turrets, or they form in situ by large scale upwelling and cooling as subvisible cirrus. Although the latter occur frequently, little is known about the exact microphysical formation mechanisms and how they can be maintained. Previous modelling efforts using various different mechanisms, however, have failed to agree with the observed properties. This project aims to improve our knowledge of the impact clouds in the tropical tropopause layer have on stratospheric humidity, by studying their formation, maintenance, and occurrence frequencies.A set of state-of-the-art numerical models will be used to simulate the clouds in the tropical tropopause layer, taking advantage of their particular strengths. These models are the Weather Research and Forecasting (WRF) Model, the GLObal Model of Aerosol Processes (GLOMAP), and the Australian Community Climate and Earth-System Simulator (ACCESS). First, the questions related to the formation and maintenance of subvisible cirrus will be addressed. In a second step the impact of subvisible cirrus and overshooting convection on the stratospheric humidity will be assessed. Both the direct effects (e.g. injection of ice particles into the stratosphere) and indirect effects (e.g. change in dynamical processes) will be studied. In order to estimate the net effect, occurrence frequencies of both cloud types will be derived from a complementary set of ground based remote sensing observations from the Darwin site and satellite observation from the International Satellite Cloud Climatology Project. The data of airborne in situ measurements which I analyzed during my PhD will help to constrain and test the model simulations. A better understanding of the complex processes related to the clouds in the tropical tropopause layer will improve their representation in numerical models and thus, enhance the quality of model predictions. This will improve our ability to constrain climate predictions due to highly uncertain ice cloud processes. Additionally, knowing the impact of these clouds on stratospheric humidity will enable an improved quantification of their climate impact.
Das Projekt "Process study of vertical mixing near the sea floor inside the central valley of the Mid-Atlantic Ridge near 37°N" wird vom Umweltbundesamt gefördert und von Alfred-Wegener-Institut für Polar- und Meeresforschung, Fachbereich Klimawissenschaften, Sektion Physikalische Ozeanographie der Polarmeere durchgeführt. Vertical mixing associated with dissipation of turbulent kinetic energy sustains the circulation of the deep and abyssal ocean. New evidence is emerging that the highest mixing rates are found within the central valleys and ridge flank (transform) canyons of mid-oceanic ridge systems. An expedition is proposed to take place in August 2010 during which near-bottom oceanographic and marine-geologic measurements will be carried out in the central valley of the Mid-Atlantic Ridge near 37°N, using an autonomous underwater vehicle (AUV), complemented by 'classical' lowered and mooring-based techniques. It is currently unclear, which physical mechanisms control the intense turbulent dissipation in deep ocean canyons. Recent studies point to a potential role of hydraulic jumps, which have been observed in shallow water studies. We aim at testing whether tidally varying hydraulic jumps can explain the observed large vertical mixing over a sill in the central valley. To resolve the jumps AUV-based high-resolution horizontal fields of near-bottom turbulent kinetic energy dissipation and of flow velocities will be obtained. Further, high-resolution AUV multi-beam echo sounder mapping will allow us to study (i) the relationship between vertical mixing processes and the bathymetry, and (ii) the dynamic processes underlying the 'mixing active' morphology.
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