The redshift distribution of gravitational lenses revisited: constraints on galaxy mass evolution     

Eran O. Ofek  Hans-Walter Rix  Dan Maoz 《Monthly notices of the Royal Astronomical Society》2003,343(2):639-652

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On 50th Anniversary of the Global Carbon Dioxide Record     

Georgii A Alexandrov  Martin Heimann  Chris D Jones  Pieter Tans 《Carbon balance and management》2007,2(1):11-2

The 50-year global CO₂ record led the way in establishing a scientific fact: modern civilization is changing important properties of the global atmosphere, oceans and biosphere. The evidence on which this scientific fact is based will be refined further, but the next challenge for scientists is broader. In addition to its traditional role in providing discovery, diagnosis, and prediction of the changes that are taking place on our planet, science has now also a role in helping society mitigate emissions by objectively quantifying them, and in helping adaptation by providing environmental forecasts on regional scales. Science is also expected to provide new options for society to tackle the transition to a new energy system, and to provide thorough environmental evaluation of all such options. This is what the meeting recognized as planetary responsibilities for scientists in the next 50 years.  相似文献   

Neue Untersuchungen über den Zusammenhang zwischen atmosphärischen Gefrierkernen und Kondensationskernen     

Hans-Walter Georgii 《Pure and Applied Geophysics》1959,42(1):62-72

Zusammenfassung Es wird über parallele Untersuchungen der atmosphärischen Gefrierkerne und der Kondensationskerne berichtet, die an drei klimatisch verschidenen Meßorten — Frankfurt/M, Taunus Observatorium und Zugspitze — bei unterschiedlichen Witterungsbedingungen vorgenommen wurden. Im Verlauf der Untersuchungen zeigte sich eine starke Abhängigkeit der Aktivierungstemperatur der Gefrierkerne von der Teilchengröße der Kondensationskerne, die mit verschiedenen Methoden nachgewiesen werden konnte.

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Summary Parallel measurements of freezing nuclei and condensation nuclei were carried out at three different locations — Frankfurt/M, Taunus observatory and Zugspitze — under various weather conditions. During these investigations a strong relation between the activation-temperature of freezing nuclei and the particle size of the condensation nuclei was detected and confirmed with different methods.

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Contributions of H2S to the atmospheric sulfur cycle     

Wolfgang Jaeschke  Hans-Walter Georgii  Hans Claude  Helmut Malewski 《Pure and Applied Geophysics》1978,116(2-3):465-475

H₂S is a most important biogenic sulfur compound with regard to the atmospheric sulfur cycle. Our present knowledge of the spatial and temporal distribution of this trace gas is rather incomplete owing to unreliable analytical methods. Therefore, a new method for the analysis of H₂S in the g-range was applied. This paper deals with the results of ground- and aircraft measurements of H₂S in unpolluted air over swamps and tidal flats. Based on the measured vertical distributions a removal coefficient of 2.3×10^–5 sec^–1 and an average lifetime of 12 hours were calculated. Some conclusions of the contribution of H₂S to the atmospheric sulfur budget are added.  相似文献   

Application of particle induced X-ray emission to aerosol long-range transport studies—transport pathways of pollution aerosol over the Atlantic ocean and Europe     

P. Metternich  H.-W. Georgii  K.O. Groeneveld 《Atmospheric Research》1986,20(1)

Particle induced X-ray emission analysis (PIXE) has been applied to aerosol long-range transport studies. The combination of a size fractionating sampler and a multi-element technique has enabled the identification of the transport pathways of individual constituents over the Atlantic Ocean and Europe. Chemical and size distribution data were obtained for aerosols collected at different sampling sites for the ground layer and the free atmosphere. Evaluation of these data under the aspect of air mass history extended the elemental determination in long range transport. A statistical technique was introduced and used to succeed in the semi-quantitative determination of transported pollutants.  相似文献   

Über Messungen der Scheindiffusion von Aerosolen in der bodennahen Luftschischt     

Dr. Hans-Walter Georgii 《Pure and Applied Geophysics》1957,36(1):127-137

Zusammenfassung Es wird über Versuche berichtet, die eine direkte und quantitative Bestimmung des Luftaustausches in Mulden und Gruben zum Ziele hatten. Die Bestimmung des in der Zeiteinheit ausgetauschten Luftvolumens erfolgt auf Grund laufender Messung der Konzentrationsabnahme künstlich erzeugter Aerosole, mit denen die in der Mulde stagnierende Luft markiert wurde. Die Geschwindigkeit der Konzentrationsabnahme und ihre Schwankungen sind ein Maß für die Größe des Austausches durch den turbulenten Mischungsprozeß. Die Persistenz der verwendeten, Aerosole wurde unter Berücksichtigung der Sedimentation, Koagulation und Eigendiffusion der Teilchen rechnerisch und experimentell abgeschätzt.

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Summary Experiments to determine directly and quantitatively the exchange of air in little valleys and ditches are being described. The air is being marked with artificially produced aerosols. The decrease of concentration of these aerosols is continuously measured and is an indication for the size of the air-exchange by turbulent mixing. The sedimentation, coagulation and diffusion of the aerosol-particles, processes which also lead to a decrease of concentration, have been carefully studied beforehand.

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Herrn Professor Dr.R. Mügge zum 60. Geburtstag gewidmet.  相似文献   

Normative productivity of the global vegetation     

Georgii A Alexandrov  Tsuneo Matsunaga 《Carbon balance and management》2008,3(1):8

Background  

The biosphere models of terrestrial productivity are essential for projecting climate change and assessing mitigation and adaptation options. Many of them have been developed in connection to the International Geosphere-Biosphere Program (IGBP) that backs the work of the Intergovernmental Panel on Climate Change (IPCC). In the end of 1990s, IGBP sponsored release of a data set summarizing the model outputs and setting certain norms for estimates of terrestrial productivity. Since a number of new models and new versions of old models were developed during the past decade, these normative data require updating.  相似文献   

Exploring spiral galaxy potentials with hydrodynamical simulations     

Adrianne D. Slyz  Thilo Kranz †  Hans-Walter Rix 《Monthly notices of the Royal Astronomical Society》2003,346(4):1162-1178

We study how well the complex gas velocity fields induced by massive spiral arms are modelled by the hydrodynamical simulations that we used recently to constrain the dark matter fraction in nearby spiral galaxies. More specifically, we explore the dependence of the positions and amplitudes of features in the gas flow on the temperature of the interstellar medium (assumed to behave as a one-component isothermal fluid), the non-axisymmetric disc contribution to the galactic potential, the pattern speed  Ω_p  , and finally the numerical resolution of the simulation. We argue that, after constraining the pattern speed reasonably well by matching the simulations to the observed spiral arm morphology, the amplitude of the non-axisymmetric perturbation (the disc fraction) is left as the primary parameter determining the gas dynamics. However, owing to the sensitivity of the positions of the shocks to modelling parameters, one has to be cautious when quantitatively comparing the simulations to observations. In particular, we show that a global least-squares analysis is not the optimal method for distinguishing different models, as it tends to slightly favour low disc fraction models. Nevertheless, we conclude that, given observational data of reasonably high spatial resolution and an accurate shock-resolving hydro-code, this method tightly constrains the dark matter content within spiral galaxies. We further argue that, even if the perturbations induced by spiral arms are weaker than those of strong bars, they are better suited for this kind of analysis because the spiral arms extend to larger radii where effects like inflows due to numerical viscosity and morphological dependence on gas sound speed are less of a concern than they are in the centres of discs.  相似文献   

Cosmological weak lensing with the HST GEMS survey     

Catherine Heymans  Michael L. Brown  Marco Barden  John A. R. Caldwell  Knud Jahnke  Chien Y. Peng  Hans-Walter Rix  y Taylor  Steven V. W. Beckwith  Eric F. Bell  rea Borch  Boris Häußler  Shardha Jogee  Daniel H. McIntosh  Klaus Meisenheimer  Sebastian F. Sánchez  Rachel Somerville  Lutz Wisotzki  Christian Wolf 《Monthly notices of the Royal Astronomical Society》2005,361(1):160-176

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Vorwort     

H. W. Georgii  G. Schumann 《Pure and Applied Geophysics》1961,50(1):3-5

Ohne Zusammenfassung  相似文献