Klimatologische Untersuchung über die geographische Verteilung der Globalstrahlung und der diffusen Himmelsstrahlung

Zusammenfassung Die vorliegende strahlungsklimatologische Studie verfolgt den Zweck, ausschließlich auf Grund von Meßergebnissen anhand ausgewählter Beispiele gegensätzlicher Großaumklimate zunächst die typischen Eigenschaften des Jahresganges der Globalstrahlung (T) und der diffusen Himmelsstrahlung (D) zu untersuchen. In Ergänzung hierzu werden häufigkeitsstatistische Betrachtungen über die Eigenheiten im Verhalten dieser Strahlungselemente im Bereich verschieden beschaffener geographischer Räume angestellt. Dabei zeigt sich, daß neben dem jahreszeitlichen Ablauf auch die Häufigkeitsverteilungen vonT undD sich zur Klimatypisierung heranziehen lassen. Ein besonderes Interesse beansprucht der jahreszeitliche Verlauf des VerhältnissesD/T in den Hauptklimazonen der Erde. Ferner wird die Breitenabhängigkeit der Globalstrahlung (T), der diffusen Himmelsstrahlung (D) und des VerhältnissesD/T behandelt. Hinsichtlich der Höhenabhängigkeit ergibt sich auf Grund des Verhaltens vonT undD für die gemäßigten Breiten eine Abnahme des QuotientenD/T. Den Abschluß bilden strahlungsklimatologische Überlegungen zur Frage der Abhängigkeit des VerhältnissesD/T von der Sonnenscheindauer im Bereich charakteristischer Klimazonen der Erde.

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Summary The present study of radiation climatology, exclusively basing on results of measurements, presents selected examples of contrary large-scale climatic conditions and examines the typical features of the annual variation of global radiation (T) and diffuse sky radiation (D). Supplementary considerations on frequency statistics refer to the peculiarities in the behaviour of these two radiation elements in different geographical areas. It results that beside the seasonal variation frequency distributions ofT andD can be used for a characterization of radiation climates. The seasonal variation of the characteristic ratioD/T in the main climatic zones of the earth is of particular interest. Furthermore, the latitudinal dependency of global radiation (T), diffuse sky radiation (D) and of the ratioD/T is discussed. As to the dependence on altitude the ratioD/T shows a decrease in temperate latitudes on account of the behaviour ofD andT. Finally climatological reflections on the dependence of the ratioD/T on the duration of sunshine in characteristic climatic regions of the earth are discussed.

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Résumé La présente étude de la climatologie du rayonnement a pour but de déterminer les propriétés typiques de l'évolution annuelle du rayonnement global (T) et du rayonnement diffus du ciel (D) et cela exclusivement sur la base de mesures faites et d'exemples choisis parmi des climats très différenciés. En complément, on prend en considération des statistiques de la fréquence des particularités de ces deux éléments à l'intérieur d'aires géographiques de climats divers. On en déduit que, à côté de l'évolution annuelle, la répartition des fréquences deT et deD permettent d'établir le type du climat. L'évolution saisonnière du rapportD/T est tout spécialement intéressant dans les principales zones climatiques de la terre. On considère ensuite la dépendance du rayonnement global (T), du rayonnement diffus du ciel (D) et du rapportD/T de la latitude du lieu. Dans les zones tempérées, le quotientD/T diminue avec l'altitude. L'auteur termine par des réflexions concernant la climatologie du rayonnement en relation avec la dépendance du rapportD/T de la durée d'insolation dans des zones climatiques caractéristiques de notre planète.

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Mit 12 Textabbildungen     

Hydrocarbon gases (C1–C5) and organic matter in bottom sediments of the Ivankovo Reservoir on the Volga River

The results of studying the composition of hydrocarbon gases (C₁–C₅) and organic matter in bottom sediments of the Ivankovo Reservoir in 1995, 2004, and 2005 are given. The methods used in the study include vapor-phase gas chromatography, instrumental pyrolysis gas chromatography, and mass-spectrometry for determining organic carbon δ ¹³C_org. The gas field of bottom sediments in different regions of the reservoir varies widely in terms of gas saturation and the spectrum of hydrocarbon gases. This suggests the heterogeneous composition of organic matter in the sediments and different conditions of its input and transformation processes. The gases were found to contain saturated hydrocarbons from methane to pentane C₁–C₅, including isomers i-C₄ and i-C₅ and unsaturated compounds C₂–C₄. A correlation was found to exist between methane distribution and the distribution of its more high-molecular homologues, which confirms their genetic relationship in bottom sediments. The obtained results show an increase in the rate of microbiological processes and organic matter transformation for most regions in the Ivankovo Reservoir. The only exceptions are the zones of Moshkovichskii Bay and the sections at Gorodnya and Konakovo, where technogenic organic matter is being accumulated. The high information value of hydrocarbon gases as biogeochemical markers of the sources of organic matter and the rates of its transformation is demonstrated. The isotopic composition of organic-matter carbon in the bottom sediments of the Ivankovo Reservoir δ ¹³C varies from ?26.21 to ?30.86‰.     

A Nd- and O-isotope study of the REE-rich peralkaline Strange Lake granite: implications for Mesoproterozoic A-type magmatism in the Core Zone (NE-Canada)

It is well established that A-type granites enriched in high field strength elements, such as Zr, Nb and the REE, form in anorogenic tectonic settings. The sources of these elements and the processes controlling their unusual enrichment, however, are still debated. They are addressed here using neodymium and oxygen isotope analyses of samples from the 1.24 Ga Strange Lake pluton in the Paleoproterozoic Core Zone of Québec-Labrador, an A-type granitic body characterized by hyper-enrichment in the REE, Zr, and Nb. Age-corrected εNd values for bulk rock samples and sodic amphiboles (mainly arfvedsonite) from the pluton range from ?0.6 to ?5.7, and ?0.3 to ?5.3, respectively. The εNd values for the Napeu Kainiut quartz monzonite, which hosts the pluton, range from ?4.8 to ?8.1. The ¹⁴⁷Sm/¹⁴⁴Nd ratios of the suite and the host quartz monzonite range from 0.0967 to 0.1659, large variations that can be explained by in situ fractionation of early LREE-minerals (Strange Lake), and late hydrothermal HREE remobilization. Oxygen isotope analyses of quartz of both Strange Lake and the host yielded δ¹⁸O values between +8.2 and +9.1, which are considerably higher than the mantle value of 5.7 ± 0.2‰. Bulk rock oxygen isotope analyses of biotite-gneisses in the vicinity of the Strange Lake pluton yielded δ¹⁸O values of 6.3, 8.6 and 9.6‰. The negative εNd values and positive δ¹⁸O values of the Strange Lake and Napeu Kainiut samples indicate that both magmas experienced considerable crustal contamination. The extent of this contamination was estimated, assuming that the contaminants were sedimentary-derived rocks from the underlying Archean Mistinibi (para-) gneiss complex, which is characterized by low εNd and high δ¹⁸O values. Mixing of 5–15% of a gneiss, having an εNd value of ?15 and a δ¹⁸O value of +11, with a moderately enriched mantle source (εNd = +0.9, δ¹⁸O = +6.3) would produce values similar to those obtained for the Strange Lake granites. Based on analogies between the Nain Plutonic Suite and the Gardar alkaline igneous province (SW-Greenland), we conclude that the Strange Lake pluton and associated REE-mineralized anorogenic bodies formed from a combination of subduction-induced fertilization of the sublithospheric mantle, crustal extension and in situ magma evolution.     

On the transport of small river run off by an alongshore baroclinic sea current

A numerical simulation has been undertaken to study the process of the transport of small river runoff by alongshore baroclinic sea currents. The study is based on the implementation of the Princeton Ocean Model (POM) under the conditions of a circular stratified basin whose surface is exposed to a transient tangential wind stress to form an alongshore baroclinic current. A baroclinic current of the downwelling type (in the Northern Hemisphere directed to the left to a sea-viewing observer) was shown to provide the carrying out of the river discharge from estuary’s vicinity more effectively than that of the upwelling type (in the Northern Hemisphere directed to the right to a sea-viewing observer).     

Main results of recent investigations into the physical mechanisms of the interaction of tropical cyclones and the ionosphere

Izvestiya, Atmospheric and Oceanic Physics - International investigations into the correlation between tropical cyclones (TCs) and the ionosphere are associated with great difficulties in proving...     

Strain accumulation along an oblique plate boundary: the Reykjanes Peninsula, southwest Iceland

We use annual GPS observations on the Reykjanes Peninsula (RP) from 2000 to 2006 to generate maps of surface velocities and strain rates across the active plate boundary. We find that the surface deformation on the RP is consistent with oblique plate boundary motion on a regional scale, although considerable temporal and spatial strain rate variations are observed within the plate boundary zone. A small, but consistent increase in eastward velocity is observed at several stations on the southern part of the peninsula, compared to the 1993–1998 time period. The 2000–2006 velocities can be modelled by approximating the plate boundary as a series of vertical dislocations with left-lateral motion and opening. For the RP plate boundary we estimate left-lateral motion  18⁺⁴₋₃ mm yr⁻¹  and opening of  7⁺³₋₂ mm yr⁻¹  below a locking depth of  7⁺¹₋₂ km  . The resulting deep motion of  20⁺⁴₋₃ mm yr⁻¹  in the direction of  N(100⁺⁸₋₆)°E  agrees well with the predicted relative North America–Eurasia rate. We calculate the areal and shear strain rates using velocities from two periods: 1993–1998 and 2000–2006. The deep motion along the plate boundary results in left-lateral shear strain rates, which are perturbed by shallow deformation due to the 1994–1998 inflation and elevated seismicity in the Hengill–Hrómundartindur volcanic system, geothermal fluid extraction at the Svartsengi power plant, and possibly earthquake activity on the central part of the peninsula.     

The multiple chronological techniques applied to the Lake Suigetsu SG06 sediment core,central Japan

The varved sediment of Lake Suigetsu (central Japan) provides a valuable opportunity to obtain high‐resolution, multi‐proxy palaeoenvironmental data across the last glacial/interglacial cycle. In order to maximize the potential of this archive, a well‐constrained chronology is required. This paper outlines the multiple geochronological techniques being applied – namely varve counting, radiocarbon dating, tephrochronology (including argon–argon dating) and optically stimulated luminescence (OSL) – and the approaches by which these techniques are being integrated to form a single, coherent, robust chronology. Importantly, we also describe here the linkage of the floating Lake Suigetsu (SG06) varve chronology and the absolute (IntCal09 tree‐ring) time scale, as derived using radiocarbon data from the uppermost (non‐varved) portion of the core. This tie‐point, defined as a distinct (flood) marker horizon in SG06 (event layer B‐07–08 at 1397.4 cm composite depth), is thus derived to be 11 255 to 11 222 IntCal09 cal. years BP (68.2% probability range).     

Zircon geochronology reveals polyphase magmatism and crustal anatexis in the Buchan Block,NE Scotland: Implications for the Grampian Orogeny

The type locality for high-temperature,low-pressure regional metamorphism,the Buchan Block in NE Scotland,exhibits profound differences to the rest of the Grampian Terrane.These differences have led some to regard the Buchan Block as an exotic crustal fragment comprising Precambrian basement gneisses and cover rocks thrust into their current position during Grampian orogenesis.Although rocks of the Buchan Block are now generally correlated with Dalradian strata elsewhere,the origin of the gneisses and the cause of the high heat flow and associated magmatism is debated.We report SIMS U-Pb and LA-ICPMS Hf isotopic data in zircon from high-grade rocks from the northeast(Inzie Head Gneiss)and northwest(Portsoy)corners of the Buchan Block.Around Inzie Head,upper amphibolite to granulite facies metasedimentary gneisses coexist with diorite sheets that were emplaced contemporaneously with partial melting of their host rocks,at least locally.U-Pb geochronology indicates a crystallisation age for the diorite of 486±9 Ma.Highly-deformed diorites within the Portsoy Gabbro have a crystallisation age of 493±8 Ma.Ages of ca.490 Ma for magmatism and high-grade metamorphism,which are broadly contemporaneous with ophiolite obduction and the onset of orogenesis,are significantly older than the established peak of Grampian metamorphism(ca.470 Ma).We propose a new model for the Grampian Orogeny involving punctuated tectonothermal activity due to tectonic switching during accretionary orogenesis.Rollback of a NW-dipping subduction zone at ca.490 Ma produced a back-arc environment(the Buchan Block)with associated arc magmatism and high dT/dP metamorphism.Arrival of an outboard arc resulted in shortening(the initial phase of the Grampian Orogeny)at ca.488 Ma.Rollback of a NW-dipping subduction zone to the SE of the ca.488 Ma suture began at 473 Ma and led to lithospheric-scale extension,decompression melting and advective heating of the middle crust,producing the widespread ca.470 Ma Grampian(classic Barrovian and Buchan)regional metamorphism.Resumed hinge advance and the final phase of shortening cut off the heat supply at ca.465 Ma,marking the end of the Grampian Orogeny.     

Theoretical and measured aeolian sand transport on a barrier island, Louisiana, USA

Over the past 100 years, the Isles Dernieres, a low lying barrier island chain along the coast of central Louisiana, Usa , has undergone more than 1 km of northward beach face retreat with the loss of 70% of its surface area. The erosion results from a long term relative sea level rise coupled with day to day wind and wave action that ultimately favours erosion over deposition. At a site in the central Isles Dernieres, 8 days of wind and beach profile measurements during the passage of one winter cold front documented aeolian erosion and deposition patterns under both onshore and offshore winds. For offshore winds, the theoretical erosion rate, based on wind shear velocity, closely matched the measured erosion rate; for onshore winds, the theoretical rate matched the measured rate only after being corrected by a factor that accounted for beach face morphology. In late February 1989, a strong cold front moved into coastal Louisiana. That cold front stalled over the Gulf of Mexico, resulting in 4 days of strong northerly winds at a study site on the Isles Dernieres. During those 4 days, the wind moved sand from the backshore to the upper beach face. When the cold front finally moved out of the area, the wind shifted to the south and decreased in strength. The onshore wind then restored some of the upper beach face sand to the backshore while increased wave activity moved the rest into the nearshore. The theoretical estimate of 1·28 m³ m^?1 for the rate of sand transport by the northerly wind compares well with the measured backshore erosion rate of 1·26 m³ m^?1, which was determined by comparing beach profiles from the start and end of the period of northerly winds. The theoretical estimate of 0·04 m³ m^?1 for the rate of sand transport by the southerly wind, however, is notably less than the measured rate of 0·45 m³ m^?1. The large discrepancy between the two rates can be explained by a difference in the shear velocity of the wind between the beach face, where the erosion occurred, and the backshore, where the wind stress was measured. Using an empirical relationship for the wind shear drag coefficient as a function of coastal environment, the theoretical estimate for the rate of sand transport by the southerly wind becomes 0·44 m³ m^?1