Horizontal, Two Point Coherence for Separations Greater Than the Measurement Height

Wind speed measurements from the test site at Rutherford Appleton Laboratory have been evaluated with respect to the spatial coherence function. The experimental arrangement provides coherence information for separation distances of 62, 80 and 102 m. These are at least three times greater than the measurement heights of 18 m and 18.7 m. Based on these experimental data and data published in the literature, different theoretical formulations are compared and a new, but simple, model for longitudinal and lateral coherence is proposed. At large separations the turbulent wind field is not isotropic, theoretical models to describe the coherence function for such distances are not available. The new model we propose builds on the classical exponential approach. It takes into account the influence of turbulence intensity and models the angular dependence of horizontal coherence. It is found that, for constant turbulence intensity, the lateral coherence decay becomes independent of the mean wind speed.     

Sweden

Four invertebrate and one fish species (Cerastoderma edule, Mya arenaria, Arenicola marina, Crangon crangon, Solea solea) from a single area of the German Wadden sea were investigated for concentrations of ten organochlorine pollutants in 1976. PCB concentrations (wet tissue basis) were predominating with 10–200 ng g^?1, while p,p′-DDD, dieldrin, α-HCH, γ-HCH and p,p′-DDE generally ranged between 1 and 10 ng g^?1. Values of α-endosulfan were even lower; p,p′-DDT, endrin and heptachlor epoxide could not be detected. Residue levels in shrimps were close to the lower range of values which have been found in this species from other areas of the North Sea since 1974. The patterns of residue concentrations in the five aquatic species were remarkably different indicating species- and compound-specific bioaccumulation. Trophic level and lipid content were shown to be responsible for PCB concentrations increasing from bivalves to fish.     

Tritium and90Sr in North Atlantic surface water

Areal distributions and complete time histories since 1952 are presented of the tritium and⁹⁰Sr concentrations in North Atlantic surface water. The distributions are based on a compilation of measured North Atlantic surface water tritium concentrations which is part of this paper and includes hitherto unpublished measurements, and on available⁹⁰Sr compilations. To reconstruct the insufficiently represented early concentrations, a two-box North Atlantic mixing model with tropospheric input is employed, for which the input is specified (on relative scales), and which is fitted to the available surface water observations. This procedure gives a natural tritium concentration of 0.2 TU (±30%), and furthermore suggests that part of the old oceanic tritium and⁹⁰Sr measurements are high. The fit requires characteristic model mixing times of 2.5 years (exchange with an intermediate-depth reservoir about three times the size of the surface box) and 30 years (loss into the deep ocean), and a tritium/⁹⁰Sr input ratio of 310 Ci/Ci. The areal distributions and time histories can serve as boundary value data for evaluations of subsurface tritium and⁹⁰Sr measurements.     

On seismic activity

Summary Seismic activity at a point of the surface of the earth up to a given time has to be computed by the total energy per unit area at the point considered in consequence of the earthquakes up to that time. The definition of seismic activity of a region can be developed from that. Seismic activity in a given time-interval results from earthquakes up to the upper limit of that interval. In consequence of a suitable valuation seismic activity is always convergent. For sufficiently large time-intervals a formal relationship between seismic activity and seismicity can be constructed.Publication No. 27 of the Institut für Geodynamik, 69 Jena (GDR), Burgweg 11. Forschungsgemeinschaft der Deutschen Akademie der Wissenschaften zu Berlin.     

Parameterizations of cloud feedback in a radiative-convective model

The effect of cloud feedback on the response of a radiative-convective model to a change in cloud model parameters, atmospheric CO₂ concentration, and solar constant has been studied using two different parameterization schemes. The method for simulating the vertical distribution of both cloud cover and cloud optical thickness, which depends on the relative humidity and on the saturation mixing ratio of water vapor, respectively, is the same in both approaches, but the schemes differ with respect to modeling the water vapor profile. In scheme I atmospheric water vapor is coupled to surface parameters, while in scheme II an explicit balance equation for water vapor in the individual atmospheric layers is used. For both models the combined effect of feedbacks due to variations in lapse rate, cloud cover, and cloud optical thickness results in different relationships between changes in surface temperature, planetary temperature, and cloud cover. Specifically, for a CO₂ doubling and a 2% increase in solar constant, in both models the surface warming is reduced by cloud feedback, in contrast to no feedback, with the greater reduction in scheme I as compared to that of scheme II.     

Ein Modell zur alpidischen Evolution und Orogenese des Tauernfensters

Zusammenfassung Die drei großen der jüngst vonSchlager &Schöllnberger für die Nördlichen Kalkalpen herausgearbeiteten stratigraphischen Wenden, die jeweils eigene Entwicklungsstadien einleiten, lassen sich auch in den im Tauernfenster vorliegenden Serien des Mesozoikums feststellen.Die Adneter Wende, die zeitlich mit dem Aufreißen der kontinentalen Kruste und der Herausbildung der Bündner Schiefer-Geosynklinale zusammenfällt, die die europäische von der ostalpinen (austroalpinen) Platte trennt, ist für den betrachteten Raum das wichtigste Ereignis zwischen variszischer und alpidischer Gebirgsbildung.Die altalpidische Orogenese setzt in der mittleren Kreide ein und erreicht in der Oberkreide mit der Subduktion der europäischen Platte unter die Sedimente der Geosynklinalfüllung (Bündner Schiefer) sowie derselben unter die ostalpine (austroalpine) Platte ihren Höhepunkt. Der Zuschub der heute im Tauernfenster vorliegenden Serien war im Campan abgeschlossen. Ebenso ist die Deckengliederung in Venedigerdecke (Zentralgneis-Komplexe mit Sedimenthülle und höhere Teildecken), Glocknerdecke (vorwiegend aus Bündner Schiefern mit Ophiolithen bestehend) und Ostalpin bereits auf die kretazischen plattentektonischen Vorgänge zurückzuführen.Die alttertiäre Regionalmetamorphose hat während ihres Höhepunktes am Ende des Eozäns die heute im Tauernfenster aufgeschlossenen Serien bis in Tiefen von 15 km oder mehr versenkt. Die anschließende, durch weitere Einengung verursachte Aufwölbung der Tauernkuppel führt zum Einströmen heißen, tiefkrustalen sauren Materials in den Kern des Antiklinoriums und — in heute noch nicht angeschnittenem Niveau -zur Anatexis.Der Flysch der Ostalpen ist aus einem paläogeographisch nördlich der Zentralgneiszone beheimateten Gebiet abzuleiten.

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The Mesozoic series of the Tauern Window are characterized by three changes in the sedimentation conditions dividing the stratigraphic evolution in four periods.In Middle and Upper Cretaceous time, the European plate is subducted under the Austroalpine plate. In Campanian time, the series of the Tauern Window are wholly covered by the Austroalpine Nappe. Three great tectonic units can be distinguished: i. e., the Venediger Nappe (consisting of Zentralgneis and its cover as well as smaller nappes and schuppen), the Glockner Nappe (mainly consisting of the Bündner Schiefer with ophiolites), and the Austroalpine nappes.The Lower Tertiary regional metamorphism culminates at the end of the Eocene at which time the series of the Tauern Window are brought into depths of 15 km or more. The succeeding arching of the Tauern cupola by continuing compression causes influx of hot acid crustal material and anatexis in the core of the anticlinorium.The flysch of the Eastern Alps derives from a zone situated paleogeographically north of the Zentralgneis zone.

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Résumé Les séries secondaires de la fenêtre des Hohe Tauern sont caractérisées par trois changements dans les conditions de la sédimentation divisant ainsi l'évolution stratigraphique en quatre périodes. Pendant le Crétacé moyen et supérieur la plaque Européenne est subductée sous les Schistes lustrés de la fosse eugéosynclinale qui, de son côté, est subductée sous la plaque Austroalpine. La formation des grandes unités tectoniques s'est achevée pendant le Crétacé supérieur, c'est-à-dire la Nappe de Venediger (constituée par le Zentralgneis et sa couverture aussi que des nappes et des écailles particulières), la Nappe du Glockner (surtout constituée par des Schistes lustrés avec des ophiolites), et les nappes Austroalpines.Le métamorphisme tertiaire culmine à la fin de l'Eocène, au terme duquel les séries de la fenêtre des Hohe Tauern sont enfouies à un profondeur de 15 km ou plus. La formation de la voûte des Hohe Tauern commence immédiatement après par rétrécissement continuel, provoquant l'admission de materiel chaud de la croûte acide et l'anatéxie dans l'intérieur de l'anticlinorium.Le flysch des Alpes orientales dérive d'une zone située paléogéographiquement au nord de la zone du Zentralgneis.

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The genesis of the methane in Lake Kivu (Central Africa)

Large amounts of methane and carbon dioxide, among other gases, are dissolved in the deep water of Lake Kivu. There is no dispute about the primarily magmatic origin of the carbon dioxide, but models of the genesis of the methane have been contradictory up to now. They have been based on too few and partly too inaccurate data.On the basis of new measurements obtained from gas and sediment samples, some of the old concepts have been further developed to a new model. According to this model, the methane is generated mainly by bacteria from the organic carbon of the sediment. It probably also contains minor amounts of thermocatalytic methane.About 70% of the organic carbon of the upper sediment is derived from mainly magmatic carbon dioxide (old carbon), which enters the biozone of the lake from the deep water by eddy diffusion and is assimilated there. The remaining 30% comes from atmospheric carbon dioxide (young carbon) assimilated in the biozone. But because methane also migrates into the lake from deeper sediment, the¹⁴C-content in the methane dissolved in the lake water is not 30% modern but only ca. 10% modern.More isotopic measurements on plankton, methane, carbon dioxide and sediment samples are necessary to support this model.

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Zusammenfassung Im Tiefenwasser des Kivusees sind u. a. große Mengen an Methan und Kohlendioxid gelöst. Während über den hauptsächlich magmatischen Ursprung des Kohlendioxids weitgehend Einigkeit besteht, sind die bisherigen Modellvorstellungen zur Genese des Methans widersprüchlich. Sie beruhen auf zu wenigen und zum Teil zu ungenauen Meß-daten.Mit Hilfe neuer Meßergebnisse an Gas- und Sedimentproben des Kivusees wurden einige der alten Vorstellungen zu einem neuen Modell weiterentwickelt. Danach ist das Methan hauptsächlich bakteriell aus dem organischen Kohlenstoff des Sediments entstanden. Wahrscheinlich enthält es auch geringe Beimengungen thermokatalytischen Methans.Der organische Kohlenstoff des oberen Sediments stammt zu rd. 70% aus dem vorwiegend magmatischen Kohlendioxid (alter Kohlenstoff), das aus dem Tiefenwasser durch turbulenten Austausch in die Biozone des Sees gelangt und dort assimiliert wird. Die restlichen 30% stammen aus dem in der Biozone assimilierten atmosphärischen Kohlendioxid (junger Kohlenstoff). Weil jedoch auch Methan aus tieferen Sedimentschichten in den See wandert, beträgt der¹⁴C-Gehalt des im Seewasser gelösten Methans nicht 30% modern, sondern nur ca. 10% modern.Weitere Isotopenuntersuchungen an Plankton-, Methan-, Kohlendioxid- und Sedimentproben sind notwendig, um das Modell abzusichern.

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Résumé De grandes quantités de méthane et d'oxyde carbonique sont dissoutes dans les eaux profondes du Lac Kicu. Alors qu'on est en général d'accord sur l'origine surtout magmatique de l'oxyde carbonique, les modèles devant représenter la genése du méthane sont contradictoires. Ils reposent sur des données trop peu nombreuses et en partie trop inexactes.A l'aide de nouveaux résultats de mesures faites sur des échantillons de gaz et du sédiment, on a développé un nouveau modèle, à partir des anciennes représentations. D'après celui-ci, le méthane provient pour sa plus grande part du carbone organique du sédiment, transformé par des bactéries. Il contient probablement des traces d'un méthane de thermocatalyse.Le carbone organique du sédiment supérieur provient pour 70% de l'oxyde carbonique surtout magmatique (carbone »ancien«), des eaux profondes parvenu, par échanges turbulents, dans la biozone du lac, où l'oxyde carbonique est assimilé. Les 30% restant proviennent de l'oxyde carbonique atmosphérique (carbone »jeune«) assimilé dans la biozone. Le méthane des couches profondes du sédiment migrant dans le lac, la teneur en¹⁴C de méthane dissous dans les eaux du lac n'est pas de 30% modernes, mais de 10% modernes.D'autres recherches sur les isotopes d'échantillons du plancton, du méthane, de l'oxyde carbonique et du sédiment du Lac Kivu seront nécessaires pour confirmer ce modéle.

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Biogene,klastische und evaporitische Sedimentation in einem mesothermen monomiktischen ufernahen See (Golf von Aqaba)

The genesis and development of a monomictic, mesothermal lake and its sediments is demonstrated by the analysis of sediment cores from different parts of the lake and from different stages of development. The compounds which build up the sediments, consist of irregular large particles from the surrounding crystalline rocks, of fine grained silt sediments from catastrophic flud deposits, of evaporitic series, and algae mats. The thickness of the different layers and their distribution in various parts of the lake; the different compounds, absolute age determinations, the carbonate layers and algae mats allow the definition of different stages of development of the lake. Causes and influences of an unusual type of monomixis with summer turnover are discussed and related to the sedimentary environment. Annual fluctuations in physical and biological limnology lead to the development of annual cycles in mat development and evaporites, which are reflected in the varved sediments. Inorganic sedimentation of terrestrial sediments, evaporites and organic matter accumulation are in shifting equilibrium which can be analysed by changes in the sediment types. Within the zone of biologic decay of algae via photosynthetic and other sulfur bacteria and heterotrophic bacteria, biogenic aragonite, Mg-Calcite and sulfides are precipitated. The autigenic dolomite occuring within the algae mats could not be attributed to biological precipitation so far. The lake started out as a lagoon approximately 4500 years B.P. Algae mat development was initiated after the lagoon was separated from the open sea (2400 B.P.). The central parts of the lake subsided at a time between 1900 and 1600 B.P. At this time the algae mat deposition, which until then took place in the whole lake, was restricted to the remaining shallow parts. Years of extremely high precipitation and catastrophic floods are represented by silt layers in the western parts of the lake, while coarser terrestrial sediments are intercalated in the algae mats of the eastern parts. Oöids, carbonate laminae, oncoliths and other types of carbonate particles within the algae mats are defined as biogenic by SEM analyses and laboratory experiments.