Progress report on rhenish massif seismic experiment

This paper presents some data and results from a seismic refraction experiment, completed mainly in 1979 in the Rhenish Massif, Federal Republic of Germany and extending through Luxembourg and Belgium into the Paris Basin in France.Velocity-depth functions have been derived for each record section independently, based on the assumption that velocity varies only with depth: these models are being improved upon by time-term and ray-tracing methods capable of handling laterally varying velocity structures and by calculating synthetic seismograms.The P_g phase which is observed very clearly on all record sections represents a refracted wave, with velocity generally > 6 km/s, from depths below 1.5–5.5 km. Along the 600 km long main profile one intracrustal reflection can usually be recognized, while from the three shorter crossing profiles in the massif two intracrustal reflectors can always be seen. Beneath much of the main profile the crust-mantle boundary is either a first order discontinuity or thin (< 1 km) transition zone at ~30 km depth. However, beneath the Ardennes and West Eifel there is a 6–12 km thick transition zone before a velocity of 8.1 km/s is reached at ~36 km depth. Beneath the crossing profiles, there is generally a transition zone < 3 km thick between crust and mantle. In some cases, there can be recognized at the top of the mantle a thin high velocity layer which is underlain by a low velocity layer which, in turn, is underlain by a reflector 4–11 km below the crust-mantle boundary.     

Versuch einer meeresmorphologischen Deutung von Satelliten-Luftbildern

Zusammenfassung Während man schon seit einiger Zeit Satelliten-Luftbilder für Festlandsbereiche interpretierte, nahm man allgemein an, daß die Meere auf diesen Bildern von einem einheitlichen und undifferenzierten Schwarz wiedergegeben würden. Es stellte sich aber heraus, daß auf manchen Bildern im Bereich der Meere deutlich verschiedene Grautönungen zu erkennen sind, die die Vermutung aufkommen lassen, es könne hier ein primärer oder zumindest sekundärer Zusammenhang mit submarinen Strukturen bestehen und es müßten sich somit Satelliten-Luftbilder auch meeresmorphologisch auswerten lassen.Zur Prüfung dieser Möglichkeit wurden in der vorliegenden Arbeit aus einer Fülle von Aufnahmen 27 Satelliten-Luftbilder mit entsprechenden Seekarten und anderen Unterlagen verglichen. Es zeigten sich an einigen Stellen verblüffende Übereinstimmungen von gewissen Grautönungen mit bekannten submarinen Formen, während an vielen anderen Stellen zunächst nur unsichere Aussagen möglich sind. Vor allem läßt sich derzeit noch nicht entscheiden, ob und wieweit primäre oder sekundäre Zusammenhänge bestehen.Die zur Beurteilung der Satellitenbilder notwendigen technischen Angaben bezüglich des Aufnahme- und Übertragungsverfahrens werden kurz resumiert, ausführlicher wird darüber an anderen Stellen (vgl. Schrifttum) berichtet.Eine kritische Diskussion des Problems der Eindringtiefe von Licht in Wasser führte zu der Annahme, daß im Bereich des Sonnenreflexes größere Tiefen als bislang vermutet ausgeleuchtet werden und sich aus der Zusammenschau aus großer Höhe veränderte optische Bedingungen ergeben können, als wir sie gewohnt sind.Insgesamt sprechen die Ergebnisse dafür, daß die Aussagefähigkeit der Methode noch an technischen Mängeln und dergleichen leidet, im Prinzip aber doch neue Beiträge zur Ozeanographie erwarten läßt.

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Essay of an ocean-morphological interpretation of Satellite-air-Pictures

Summary While for some time, Satellite-air-Pictures have already been interpreted for evaluation in the continental sphere, it was generally assumed that the oceans in such pictures were shown in an uniform and undifferentiated black colour. However, it was concluded that on some of these photos, showing the oceans, greyish shades were clearly visible which fact led to the assumption that one is confronted here primarily or, at least, secondarily by a coherence with submarine structures and, therefore, Satellite-air-Photos could perhaps also be construed in an ocean-morphological way.In order to test such a possibility, 27 Satellite-air-Photos out of a lot of pictures have been compared with the respective sea-charts and other data. In some instances, amazing conformities of certain greyish hues with the known substratal forms got visible, while in many other spots, so far, only vague statements can be made. First of all, at this point, it cannot as yet be decided whether and how far a primary or secondary context exists.The necessary technical data for the evaluation of such Satellite-air-Photos, with reference to the receiving and transmitting procedures, will be summarized in short, yet reports in greater detail can be found in the comparable literature.A critical discussion of the problems of depth of light-penetration into the water led us to the assumption that in the sphere of sunreflexes greater depths than so far presumed can be reached and, by the synoptical view from enormous heights, completely changed optical conditions may result, than we are so far used until now.Altogether, the results prove that the capacity of this method is still suffering from technical shortcomings, principally however, new contributions to oceanography can be expected.

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Essai d'une exploitation des images par satellites pour la morphologie marine

Résumé Tandis que depuis quelque temps déjà on interprétait des images par satellites de zones continentales, il était admis en général que les mers, sur ces images, seraient rendues par un «noir» uniforme sans nuances. Mais en fait, sur plus d'une image, on peut reconnaître distinctement dans les zones maritimes diverses tonalités de gris qui donnent à penser qu'il pourrait y avoir là une relation de premier ou tout au moins de second ordre avec des structures sous-marines. Dans ces conditions des images par satellites devraient offrir un intérêt pour la morphologie marine.Afin de vérifier cette possibilité, dans la présente étude, on a comparé 27 images par satellites, tirées d'un grand nombre de prises de vues, avec les cartes marines correspondantes et d'autres documents. En quelques points apparuent des concordances surprenantes entre certains tons de gris et des formes sous-marines connues, tandis qu'en beaucoup d'autres endroits on ne peut encore rien préciser pour le moment. Avant tout, en l'état actuel des choses, on ne peut encore affirmer qu'il existe — et dans quelle mesure — des concordances d'ordre primaire ou secondaire.Les données techniques nécessaires pour l'appréciation des images par satellites en ce qui concerne les procédés de prises de vue et de transmission, sont résumées succinctement; elles sont traitées de façon plus détaillée ailleurs (voir bibliographie).Une discussion critique du problème de la profondeur de pénétration de la lumière dans l'eau, permet de supposer que dans la zone où pénètre la lumière solaire, des profondeurs plus grandes que celles admises jusqu'alors sont éclairées et aussi que de la «vue d'ensemble», de haute altitude, peuvent résulter des conditions optiques qui diffèrent de celles auxquelles nous sommes accoutumés.Dans l'ensemble les résultats montrent que les informations à attendre de la méthode, souffrent encore d'un insuffisance de moyens techniques et autres mais laisse entrevoir, en principe, de nouvelles contributions à l'océanographie.

     

First application of MC2-AQ to multiscale air quality modelling over Europe

A three-dimensional air quality model (MC2-AQ) developed for studying oxidant chemistry on regional to urban scales over North America was adapted and implemented for European conditions. The modelling system is based on the Canadian Mesoscale Compressible Community (MC2) Model, a non-hydrostatic meteorological model, to which modules permitting on-line calculations of chemical transformations, anthropogenic and biogenic emissions, and deposition were added. The transport of chemical species is done on the same grid and with the same advection, convection, and diffusion schemes as are used for the meteorological fields. The developed model is highly flexible and was adapted to different scales by allowing for self-nesting. In this paper we present model results for a high-ozone episode, June 18–26, 2000, over Europe. The modelling system was able to reproduce general characteristics (growth, extent, and dissipation) of the pollution episode. Accumulation of ozone precursors during weak wind and high-temperature synoptic conditions was essential for episode formation. Subsequent episode development and advancement across Europe was driven by frontal systems. A stationary front associated with a low-pressure system over Ukraine prevented the further eastward transport of the polluted air mass. The episode was terminated after the passage of a cold front advecting relatively clean Atlantic air mass.     

Patchy structure and selective extinction

Based on diurnal values of the total radio-flux density at 10.7 cm as well as on corresponding Zürich numbers the relation giving the radio-flux as function ofR is established. The behaviour of low and high values ofR andF ₂₈₀₀ during the time interval 1957–1976 is studied. Preliminary conclusions drawn by other investigators are confirmed. A prediction of the total radio-flux for the 22nd solar cycle is given.     

Motions and slamming impact on catamaran

Prediction of craft motions and the dynamic loads acting on a catamaran hull are of great importance to the designer. This paper presents the motions of a Vosper International catamaran in head seas with and without forward speed. Two approaches are used—strip theory and the 3D pulsating source method. A method to predict slamming loads acting on this catamaran section using Computational Fluid Dynamics is presented. The loads acting on catamaran hulls and the cross structure are illustrated.     

Numerical investigation into the application of response conditioned waves for long-term nonlinear fatigue analyses of rigid hulls

Previous studies of response conditioned wave methods have been focused on their applicability to the prediction of extreme nonlinear wave-induced load effects. The results showed that theses methods can be used to accurately and efficiently predict the nonlinear short-term probability distributions for rigid hull responses. This has led us to investigate how response conditioned wave methods can be used for long-term nonlinear fatigue analyses, and with which accuracy this can be done. In this paper we present the results from our investigation. The studies were performed using a container vessel with a length between perpendiculars of 281 m. Calculations were done with a nonlinear strip theory method in which the hull of the vessel was assumed to be rigid. The most likely response wave (MLRW) method was used to condition the waves. Only head seas were considered. We found that the MLRW method under-predicted the long-term fatigue damage by 3%. The method, however, required a simulation time that was approximately three orders of magnitude less than that required for a conventional long-term nonlinear analysis based on random irregular waves. A preliminary investigation showed that due to lacking springing and whipping contributions the MLRW method under-predicted the fatigue damage for a flexible hull by approximately 50%. Several comments about a more accurate extension of the proposed method to flexible hulls are included.     

Analysis of Vertical Turbulent Heat Flux Limit in Stable Conditions with a Local Equilibrium, Turbulence Closure Model

Assuming that the vertical turbulent heat flux vanishes at extremely stable conditions, one should expect its maximal absolute value to occur somewhere at moderate stability, between a neutral and extremely stable equilibrium. Consequently, in some situations duality of solutions may be encountered (e.g. two different values of temperature difference associated with the same values of heat flux and wind speed). A quantitative analysis of this feature with a local equilibrium Reynolds-stress model is presented. The fixed-wind / fixed-shear maximum has been identified both in the bulk and in single-point flux–gradient relationships (that is, in the vertical temperature gradient and wind-shear parameter domain). The value of the Richardson number corresponding to this maximum is derived from the model equations. To study the possible feedback in strongly stable conditions, weak and intense cooling scenarios have been simulated with a one-dimensional numerical, high-resolution atmospheric boundary-layer model. Despite the rapid cooling, flow decoupling at the surface has not been observed; instead, a stability-limited heat flux is maintained, with a gradual increase of the Richardson number towards the top of the turbulent layer, with some signs of oscillatory behaviour at intermediate heights. Vertical changes of wind shear and the Brunt–Väisälä frequency display a remarkably non-monotonic character, with some signs of a gradually developing instability.     

Surface-Layer Flux–Gradient Relationships over Inclined Terrain Derived from a Local Equilibrium,Turbulence Closure Model

Derivation of surface-layer flux–gradient relationships from a local-equilibrium, turbulence-closure model for a forced flow over inclined terrain is presented. Results are shown as a generalization of Monin–Obukhov universal functions respesenting non-dimensional wind and temperature gradients.