Shock waves—Phenomenology,experimental, and numerical simulation

Abstract— The purpose of this paper is to review the results of long‐term cooperation between Dieter Stöffler and the authors in the field of shock wave deformation of minerals and rocks. First, the principal phenomena of shock wave generation and propagation, predominantly in solid media, are presented, and then analytical and numerical mathematical treatment of shock wave processes on the basis of mass, momentum, and energy conservation laws will be described and discussed. Experimental methods of shock wave investigations by means of impact and explosive techniques are summarized, including hypervelocity acceleration facilities and high‐pressure explosive devices. Shock pressure barometry by means of mineralogical evidence of distinct material phase transitions and characteristic shock structures is also discussed.     

A possible azhdarchid pterosaur from the Crato Formation (Early Cretaceous,Aptian) of northeast Brazil

The partially articulated, distal portion of a left wing finger of a pterosaur from the Crato Formation of northeast Brazil has a T-shaped cross-section to the second and third phalanges. This cross-sectional shape is one of several characters diagnostic of the pterodactyloid pterosaur family Azhdarchidae (Unwin & Lu 1997). Until now, this family of pterosaurs was known exclusively from the Late Cretaceous. The specimen described here may be the first recorded azhdarchid from the southern hemisphere and the earliest recorded member of the family.     

Simulation of the effects of geochemical reactions on groundwater quality during planned flooding of the Königstein uranium mine, Saxony, Germany

Uranium mining in southeastern Germany resulted in significant environmental risks. Closure of the mines and subsequent rises of water levels may result in heavy-metal and radionuclide-bearing mine waters penetrating aquifers that are used for water supply. While there are certain (geo-)technical constraints on the schedule with which flooding of the mines can proceed, this process must not result in aggravating the problem of metal release. Evaluation of the likely 'natural' geochemical situation of Königstein mine after mining has ceased, and different scenarios for the release of metals indicates that rapid flooding, albeit avoiding unnecessary aeration of the waters, is likely to result in reducing conditions and consequently low U-solubilities.     

The Role of Ground Water in Sub-Saharan Africa

Although water resources managers speak of a water crisis in Africa, the management of ground water has to date not featured strongly in national and regional African water agendas. Examination of the physical environment of the continent and, in particular, the water resources in relation to the socioeconomic landscape and regional development challenges makes it clear that widely occurring, albeit largely low-yielding, ground water resources will be crucial in the achievement of water security and development. Ground water is important primarily in domestic water and sanitation services, but also for other local productive needs like community gardens, stock watering, and brick-making, all essential to secure a basic livelihood and thus to alleviate poverty. Despite the importance of small-scale farming in Africa, there is little information on the present and potential role of ground water in agriculture. In contrast to its socioeconomic and ecological importance, ground water has remained a poorly understood and managed resource. Widespread contamination of ground water resources is occurring, and the important environmental services of ground water are neglected. There appear to be critical shortcomings in the organizational framework and the building of institutional capacity for ground water. Addressing this challenge will require a much clearer understanding and articulation of ground water's role and contribution to national and regional development objectives and an integrated management framework, with top-down facilitation of local actions.     

Decadal-scale variations of water mass properties in the deep Weddell Sea

Data from cruises between 1989 and 2003 with FS Polarstern were used to construct section-wide potential temperature and salinity time series of the main water masses in the Weddell Gyre. In tandem with these CTD data, two time series between 1989 and 1995 are presented from moored instruments in the central Weddell Sea. The regional and methodological consistency of the dataset allows us to quantify variations which are not visible in less homogeneous datasets. The data reveal significant temperature and salinity variations of the Warm Deep Water and the Weddell Sea Bottom Water on a decadal time scale. The longest time series were obtained at the prime meridian. Here warming is observed in the Warm Deep Water from 1992 to 1998 followed by cooling. In the Weddell Sea proper, measurements of instruments moored in the Weddell Sea Bottom Water layer recorded a temperature increase over 6 years at a rate of 0.01 °C a^–1. After the mooring period, CTD casts in 1998 point to a weakening of the trend. The warming trend in the bottom water occurs over most of the Weddell Sea, as detected in the additional CTD surveys. The variations are close to the detection level in the voluminous Weddell Sea Deep Water. The initial warming trend of the Warm Deep Water is consistent with warming trends reported in literature of subsurface waters of the Antarctic Circumpolar Current. The reversal of the trend in the Weddell Sea seems to be related to variations of the atmospheric conditions which can affect both the intrusion of Circumpolar Deep Water from the north and the circulation of the Weddell Gyre. Because the Warm Deep Water is the major source water for the formation of deep and bottom water in the Weddell Sea, it is suggested that its increase in temperature and salinity is likely to at least partly cause the variations which were observed in the bottom water.Responsible Editor: Jörg-Olaf Wolff     

Time and height variability of the sensible heat flux in the surface layer

The energy-budget concept is used together with a high resolution spectral radiation model to study the time and height variation of the sensible heat flux and of the eddy thermal diffusivity for an actual case up to 50 m above ground. A data set of 32 h is chosen for this study. Time-height cross-sections of the local enthalpy changes, and the radiative and the sensible heat flux divergences are presented, which show the interaction of the two energy fluxes. It can be seen, for example, that during the transient hours from night to day the sensible heat flux divergence plays an outstanding role in the warming of the atmosphere, while during the clear night radiative cooling exceeds the cooling caused by the sensible heat flux. For the layer under consideration (0-50 m) a constancy of the sensible heat flux within 10% is obtained for seven hours only, namely for the time around noon and in the early afternoon. Selected night-time profiles of the thermal diffusivity are shown, which have their maximum below 48.3 m.The accuracy of the energy-budget method is studied in detail. The tests show that a high accuracy, with errors even less than 10% for some hours, can be expected, if special micrometeorological studies are made during the field phase and a layer depth of 50 cm or less is used in the radiation model.     

Impact of chemical and meteorological boundary and initial conditions on air quality modeling: WRF-Chem sensitivity evaluation for a European domain

This study evaluates the impact of different chemical and meteorological boundary and initial conditions on the state-of-the-art Weather Research and Forecasting (WRF) model with its chemistry extension (WRF-Chem). The evaluation is done for July 2005 with 50 km horizontal resolution. The effect of monthly mean chemical boundary conditions derived from the chemical transport model LMDZ-INCA on WRF-Chem is evaluated against the effect of the preset idealized profiles. Likewise, the impact of different meteorological initial and boundary conditions (GFS and Reanalysis II) on the model is evaluated. Pearson correlation coefficient between these different runs range from 0.96 to 1.00. Exceptions exists for chemical boundary conditions on ozone and for meteorological boundary conditions on PM₁₀, where coefficients of 0.90 were obtained. Best results were achieved with boundary and initial conditions from LMDZ-INCA and GFS. Overall, the European simulations show encouraging results for observed air pollutant, with ozone being the most and PM₁₀ being the least satisfying.     

Geologische Bearbeitung Südwest-Ägyptens

Zusammenfassung In einem auf die Klärung stratigraphischer, fazieller, paläogeographischer, hydrogeologischer und paläoklimatischer Fragen ausgerichteten Forschungsprogramm wird eine Bearbeitung Südwest-Ägyptens durchgeführt. Neben dem Nachweis einer altpaläozoischen — vermutlich ordovizischen — Vereisung und jüngerer, mariner paläozoischer Schichten erfolgte bisher eine Gliederung der ehemaligen Nubischen Serie dieses Gebietes in mehrere marine und kontinentale Sedimentationszyklen von jurassischem bis oberkretazischem Alter. Eine detaillierte geologische Karte von Südwest-Ägypten ist in Vorbereitung.

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First results of geological research in Southwestern Egypt are presented, which are part of a programme dedicated to stratigraphical, sedimentological, paleogeographical and hydro geological as well as paleoclimatical questions. The research programme is sponsored by Deutsche Forschungsgemeinschaft, it is carried out in cooperation with the Academy of Science of Egypt and it is backed by Continental Oil Company.Apart from the proof of an Early Paleozoic glaciation of probably Ordovician age, marine sediments of younger Paleozoic ages were found. The former Nubian Sandstone was subdivided into several formations of shallow marine to continental origin of Jurassic to Late Cretaceous age. A detailed geological map of Southwestern Egypt is under preparation.

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Résumé Les premiers résultats de recherche géologique dans le Sud-Ouest de l'Egypte sont présentés; ils font partie d'un programme d'étude des questions stratigraphiques, sédimentologiques, paléogéographiques, hydrogéologiques et paléoclimatiques. Ce programme est subventionné par la Deutsche Forschungsgemeinschaft, réalisé en coopération avec l'Académie des Sciences d'Egypte et assisté par Conoco.Outre la preuve d'une glaciation d'âge paléozoique — probablement ordovicien — et de sédiments marins paléozoiques plus jeunes, une division de l'ancien «Grès Nubie» de cette région en plusieurs cycles de sédimentation marine et continentale du Jurassique au Crétacé supérieur fut effectuée. Une carte géologique détaillée du Sud-Ouest de l'Egypte est en préparation.

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