Luftelektrische Tagesgänge und Massenaustausch im Hochgebirge der Alpen

Zusammenfassung Es wird über die Ergebnisse luftelektrischer Untersuchungen auf dem Jungfraujoch (Schweiz) und ihre Deutung berichtet. Während zweier Meßperioden von je mehrwöchiger Dauer wurden das luftelektrische Potentialgefälle und der vertikale Leitungsstrom registriert; bearbeitet sind zunächst die Tagesgänge an klaren Tagen mit Hochdruckwetter. Die Tagesvariationen der drei luftelektrischen Elemente: Potentialgefälle, Vertikalstrom und Leitfähigkeit zeigen, daß auf dem Jungfraujoch im Sommer und im Herbst zwei ganz verschiedene Typen des luftelektrischen Verhaltens zu erkennen sind: Im Sommer herrscht auch an dieser Höhenstation der von den Tieflandstationen bekannte Typ vor, bei dem das Potentialgefälle angenähert invers zur Leitfähigkeit und zum Vertikalstrom verläuft. Im Herbst dagegen verlaufen Potentialgefälle und Vertikalstrom im wesentlichen gleichsinnig bei gegensinniger, aber schwächer ausgeprägter Tagesvariation der Leitfähigkeit. Im Sommer herrscht also auch in Jungfrauhöhe in den Alpen derkontinentale Typ, während sich im Herbst die Verhältnisse demozeanischen Typ annähern. Eine genauere Analyse ergibt, daß im Sommer die Tagesvariation desSäulenwiderstandes (columnar resistance) über dem Jungfraujoch in enger Korrelation zum örtlichen Widerstand der Luft an der Meßstelle (Reziprokwert der Leitfähigkeit) steht, während dies im Herbst nicht mehr der Fall ist.Zur Deutung dieser Feststellungen ist folgendes anzunehmen: Im Hochsommer wirkt die Tagesschwankung des vertikalen Massenaustausches aerosolverändernd bis in die Höhe des Alpenkammes, erkennbar daran, daß die Steuerung der luftelektrischen Tagesvariationen im wesentlichen von den unteren Schichten her erfolgt. Im Herbst dagegen ist dieser Einfluß in Kammhöhe der Alpen nahezu geschwunden; die Austauschvariation dringt nicht mehr bis in diese Höhen vor. Die verbleibenden Variationen der Leitfähigkeit deuten auf advektiven Luftaustausch hin. Das Verhalten des Dampfdruckes auf dem Jungfraujoch im Sommer und Herbst stützt diese Deutung.

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Summary The present paper gives an account of researches on atmospheric electricity carried out at Jungfraujoch (Switzerland). During two periods of several weeks each the potential gradient and the vertical air-earth current have been recorded. In the first place the diurnal variations on fine days at high pressure weather situation are elaborated. The daily variations of the three elements: potential gradient, vertical current, and conductivity, show that in summer and autumn two different types of the conditions of atmospheric electricity can be discerned: In summer the well-known type of the lowland stations is predominating also at this high altitude station, the type where the potential gradient is very nearly inverse to conductivity and vertical current. In autumn on the contrary the potential gradient and the vertical current are essentially parallel since the conductivity shows a slight diurnal variation in contrary sense. Thus, in summer prevails at the altitude of Jungfraujoch in the Alps thecontinental type, whilst in autumn the conditions approach to theoceanic type. It results from a rigorous analysis that in summer the diurnal variation of thecolumnar resistance on Jungfraujoch is in close correlation to the local air resistance (the reciprocal figure of conductivity) at the measuring point, whereas in autumn this is no longer the case.To explain these results we must assume as follows: In midsummer the diurnal variation of vertical mass exchange produces alterations of the aerosol up to the altitude of the crest of the Alps, which is perceptible from the fact that diurnal variations of atmospheric electricity start essentially from the lower layers. In autumn this influence has almost disappeared in the summit altitude of the Alps, as the daily variation of exchange does not advance to this altitude. The remaining variations of the conductivity point at an advective exchange of air. The behaviour of vapour pressure in summer and autumn at Jungfraujoch gives support to this interpretation.

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Résumé L'article traite des résultats de recherches d'électricité atmosphérique au Jungfraujoch (Suisse) et de leur interprétation. Deux périodes de mesures de plusieurs semaines chacune ont été consacrées à l'enregistrement du gradient de potentiel et du courant vertical. On décrit tout d'abord la variation diurne lors des jours sereins de temps anticyclonique. On distingue an Jungfraujoch en été et en automne respectivement deux types très différents de la marche diurne du gradient de potentiel, du courant vertical et de la conductibilité. En été le type bien connu des stations de plaine pour lequel le gradient de potentiel varie à peu près inversement à la conductibilité et au courant vertical s'observe aussi au Jungfraujoch. Par contre en automne le gradient de potentiel et le courant vertical varient en général dans le même sens, tandis que la conductibilité varie, elle, en sens contraire, bien que faiblement. Il y a donc à l'altitude du Jungfraujoch en été le «type continental», alors qu'en automne les conditions se rapprochent du «type océanique». Une analyse plus détaillée montre qu'en été la variation diurne de la «résistance tubulaire» (columnar resistance) au-dessus du Jungfraujoch est en liaison étroite avec la résistance locale de l'air au point de mesure (inverse de la conductibilité), tandis qu'en automne ce n'est plus le cas.Pour interpréter ces résultats il faut admettre ce qui suit: En été la variation diurne de l'échange vertical turbulent modifie les aérosols jusqu'au niveau de la crête alpine, ce que l'on reconnaît au fait que les variations diurnes des phénomènes d'électricité atmosphérique sont largement conditionnés par les couches basses. En automne par contre cet effet a disparu sur les Alpes, car la variation de l'échange turbulent n'a plus d'influence à ce niveau. La variation de la conductibilité qui subsiste suggère un échange d'air par advection. L'allure de la pression de vapeur d'eau au Jungfraujoch en été et en automne confirme cette hypothèse.

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Mit 11 Textabbildungen.     

Zur Entwicklung der luftelektrischen Grundanschauungen

Zusammenfassung Die luftelektrischen Grundanschauungen haben im Laufe der Entwicklung mehrfach erhebliche Wandlungen durchgemacht. Auf die Entwicklungsperiode, in der man die auffallenden Parallelen im Verhalten luftelektrischer und meteorologischer Größen aufzuklären sich bestrebte — sie findet etwa mitF. Exner ihr Ende—, folgt eine Phase bewußter Emanzipation der luftelektrischen Forschung, während der man in den meteorologischen Einflüssen nur Störungen sieht. Etwa in den zwanziger Jahren beginnt dann eine Reaktion gegen dieses Isolationsbestreben und mit der früher lange vergeblich versuchten Aufklärung des luftelektrischen Grund- und Existenzproblems leitet sich eine neue Entwicklungsphase ein, die man sinngemäß als korrelative Phase bezeichnen möchte. Nach einer eingehenden und nach den inneren gründen dieser mehrmaligen Schwenkung suchenden Darstellung wird im zweiten Teil der vorliegenden Arbeit das Problem der luftelektrischen Tagesgänge behandelt und als Beweis für die komplexe elektro-meteorologische Arbeits- und Betrachtungsweise in seinen neuesten Entwicklungen kurz dargestellt. Die enge Verbindung zwischen dem luftelektrischen Geschehen und dem vertikalen atmosphärischen Massenaustausch legt die Benutzung luftelektrischer Untersuchungen in der Austausch-und Luftkörperforschung nahe.

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Summary In the course of the development the fundamental notions about atmospheric electricity have experienced considerable changes. In a first period expiring about withF. Exner, one tried to explain the striking parallels of electrical and meteorological phenomena; then follows a period with a distinct emancipation of atmospheric electricity, where meteorological influences were admitted but as perturbations. In the twenties begins a reaction to this isolationist views and a new evolution starts which might be called correlative phase. The author analyses and explains these repeated changes, and in a second part he discusses the problem of the diurnal variation of atmospheric electricity and shows the complexity of electro-meteorological relations. The close connexion between the phenomena of atmospheric electricity and the turbulent vertical exchange urges to employ investigations of atmospheric electricity for investigations in exchange and air-mass research.

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Résumé En matière d'électricité atmosphérique les points de vue ont souvent varié considérablement. Dans une première période allant jusqu'àF. Exner environ, on a essayé d'expliquer le parallélisme évident entre les phénomènes électriques et météorologiques; puis on a envisagé les premiers pour eux-mêmes, indépendamment des influences météorologiques considérées alors comme des «perturbations». Autour des années 1920, une réaction se dessine contre cette discrimination, et une nouvelle phase commence que l'on pourrait appeler corrélative. Après une analyse approfondie de ces fluctuations de la théorie, l'auteur aborde dans la deuxième partie de son étude le problème des variations diurnes des phénomènes électriques et montre la complexité des relations les unissant à ceux de l'atmosphère ellemême. La liaison étroite entre les phénomènes de l'électricité atmosphérique et les échanges turbulents de masse dans la verticale prouve l'utilité des recherches électriques pour l'étude de cet échange et pour celle des masses d'air de l'atmosphère.

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Mit 14 Textabbildungen.

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Herrn Prof. Dr.H. Benndorf zum 80. Geburtstag gewidmet.     

Climate variability and trends in downscaled high-resolution simulations and projections over Metropolitan France

In order to fulfill the society demand for climate information at the spatial scale allowing impact studies, long-term high-resolution climate simulations are produced, over an area covering metropolitan France. One of the major goals of this article is to investigate whether such simulations appropriately simulate the spatial and temporal variability of the current climate, using two simulation chains. These start from the global IPSL-CM4 climate model, using two regional models (LMDz and MM5) at moderate resolution (15–20 km), followed with a statistical downscaling method in order to reach a target resolution of 8 km. The statistical downscaling technique includes a non-parametric method that corrects the distribution by using high-resolution analyses over France. First the uncorrected simulations are evaluated against a set of high-resolution analyses, with a focus on temperature and precipitation. Uncorrected downscaled temperatures suffer from a cold bias that is present in the global model as well. Precipitations biases have a season- and model-dependent behavior. Dynamical models overestimate rainfall but with different patterns and amplitude, but both have underestimations in the South-Eastern area (Cevennes mountains) in winter. A variance decomposition shows that uncorrected simulations fairly well capture observed variances from inter-annual to high-frequency intra-seasonal time scales. After correction, distributions match with analyses by construction, but it is shown that spatial coherence, persistence properties of warm, cold and dry episodes also match to a certain extent. Another aim of the article is to describe the changes for future climate obtained using these simulations under Scenario A1B. Results are presented on the changes between current and mid-term future (2021–2050) averages and variability over France. Interestingly, even though the same global climate model is used at the boundaries, regional climate change responses from the two models significantly differ.     

Climate and climate change in western canada as simulated by the Canadian regional climate model

Abstract

A þrst climate simulation performed with the novel Canadian Regional Climate Model (CRCM) is presented. The CRCM is based on fully elastic non‐hydrostatic þeld equations, which are solved with an efþcient semi‐implicit semi‐Lagrangian (SISL) marching algorithm, and on the parametrization package of subgrid‐scale physical effects of the second‐generation Canadian Global Climate Model (GCMII). Two 5‐year integrations of the CRCM nested with GCMII simulated data as lateral boundary conditions are made for conditions corresponding to current and doubled CO₂ scenarios. For these simulations the CRCM used a grid size of 45 km on a polar‐stereographic projection, 20 scaled‐height levels and a time step of 15 min; the nesting GCMII has a spectral truncation of T32, 10 hybrid‐pressure levels and a time step of 20 min. These simulations serve to document: (1) the suitability of the SISL numerical scheme for regional climate modelling, (2) the use of GCMII physics at much higher resolution than in the nesting model, (3) the ability of the CRCM to add realistic regional‐scale climate information to global model simulations, and (4) the climate of the CRCM compared to that of GCMII under two greenhouse gases (GHG) scenarios.     

Rječina River sediments (Croatia): from captured spring to polluted prodelta

Surface sediments (fraction <63 μm) from the source to the mouth of the Rječina, short (18.3 km) karst allogenic river in Croatia, which is an important source of drinking water, were studied to investigate their mineral (by XRD) and chemical (by ICP-MS) composition to check possible anthropogenic influence at the lower course due to paper industry and mills, and in the prodelta area from untreated municipal sewage and the large harbor of Rijeka town. In all analyzed sediment samples and in the sandstone source, rock quartz is a major mineral, while feldspar and mica group minerals are less abundant. Chlorite is a minor or trace mineral in all samples. Calcite and dolomite are abundant in the river prodelta, reflecting changes in bedrock lithology from flysch to carbonates. In river sediments, Fe is the most abundantly analyzed element, while Ca is the most abundant in prodelta sediments. Concentrations of Al, Mn, Ni, Cr, Co, La and Nd decrease downstream, while Mg, S, Na, B, Pb, Zn, As, Sn, U, Mo, Hg and Ag have relatively higher concentration in prodelta sediments. The results are compared with sediments of other rivers in the area: Raša, Rižana and Dragonja, as well as with those of the Rosandra Creek (Italy). Sediments in the Raša River showed similar behavior as those in the Rječina, as the highest concentration of metals was found in the restricted upper part of the estuary, characterized by rapid deposition of clay particles and terrestrial sedimentary organic matter. The comparison also showed that the most contaminated were the sediments from the Rižana, followed by those from the Rječina and Rosandra Creek, which had similar results. Among the studied elements, As was present in all sediment samples at concentrations >6 ppm that might have the lowest toxic effects. At the lower Rječina and in prodelta sediments, Pb was also present at slightly elevated concentrations (>31 ppm) that could cause such effects. Concentrations of Zn in the prodelta correspond to those occurring in moderately polluted sediments (90–200 ppm). In the prodelta sediments, Hg is slightly below toxicity threshold (1 ppm), while Ag is present at toxicity threshold (0.5 ppm) or close to it. Rječina River could act as a good illustrative example for behavior of toxic metals in allogenic karstic rivers, in which accumulation of anthropogenically introduced pollutants usually occurs in their estuaries, as a result of transport and deposition of fine particles.     

Determination of Rare Earth Elements, Sc, Y, Zr, Ba, Hf and Th in Geological Samples by ICP-MS after Tm Addition and Alkaline Fusion

We present a revised method for the determination of concentrations of rare earth (REE) and other trace elements (Y, Sc, Zr, Ba, Hf, Th) in geological samples. Our analytical procedure involves sample digestion using alkaline fusion (NaOH-Na₂O₂) after addition of a Tm spike, co-precipitation on iron hydroxides, and measurement by sector field-inductively coupled plasma-mass spectrometry (SF-ICP-MS). The procedure was tested successfully for various rock types (i.e., basalt, ultramafic rock, sediment, soil, granite), including rocks with low trace element abundances (sub ng g⁻¹). Results obtained for a series of nine geological reference materials (BIR-1, BCR-2, UB-N, JP-1, AC-E, MA-N, MAG-1, GSMS-2, GSS-4) are in reasonable agreement with published working values.     

Magmatic history and geophysical signature of a post-collisional intrusive center emplaced near a crustal-scale shear zone: the Plechý granite pluton (Moldanubian batholith,Bohemian Massif)

The Plechy pluton, southwestern Bohemian Massif, represents a late-Variscan, complexly zoned intrusive center emplaced near the crustal-scale Pfahl shear zone; the pluton thus provides an opportunity to examine the interplay among successive emplacement of large magma batches, magmatic fabric acquisition, and the late-Variscan stress field associated with strike-slip shearing. The magmatic history of the pluton started with the emplacement of the porphyritic Plechy and Haidmühler granites. Based on gravity and structural data, we interpret that the Plechy and Haidmühler granites were emplaced as a deeply rooted, ∼NE–SW elongated body; its gross shape and internal fabric (steep ∼NE–SW magmatic foliation) may have been controlled by the late-Variscan stress field. The steep magmatic foliation changes into flat-lying foliation (particularly recorded by AMS) presumably as a result of divergent flow. Magnetic lineations correspond to a sub-horizontal ∼NE–SW finite stretch associated with the divergent flow. Subsequently, the Třístoličník granite, characterized by steep margin-parallel magmatic foliation, was emplaced as a crescent-shaped body in the central part of the pluton. The otherwise inward-younging intrusive sequence was completed by the emplacement of the outermost and the most evolved garnet-bearing granite (the Marginal granite) along the southeastern margin of the pluton. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Intrusion versus inversion—a 3D density model of the southern rim of the Northwest German Basin

An unsolved problem of regional importance for both the evolution and structure of the Northwest German Basin is the existence or non-existence of the so-called Bramsche Massif. Explaining the nature of this massif and the cause of a related strong, positive Bouguer anomaly (Bramsche Anomaly) is critical. In the study described here, we tested an existing “intrusion model” against a newer “inversion model” in the southern Northwest German Basin. In the intrusion model, the strongly-positive Bouguer anomaly represents the gravity effect of an intrusion at depths between 6 and 10 km. More recent interpretations invoke tectonic inversion rather than intrusion to explain increased burial and the low level of hydrocarbon maturity found in boreholes. We tested these different interpretations by constructing 3D forward density models to 15 km depth. The intrusion model was updated and adjusted to incorporate recent data and we also modelled pre-Zechstein structures using different scenarios. The final model has a very good fit between measured and modelled gravity fields. Based on currently available seismic and structural models, as well as borehole density measurements, we show that the positive Bouguer anomaly cannot be modeled without a high-density, intrusive-like body at depth. However, further in-sight into the crustal structures of the Bramsche region requires more detailed investigations. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Geotectonics,karst morphology,and environmental problems

Relationships among tectogenetic karst types, major morphologic units, and environmental consequences are discussed. The development of urban centers and in-dustrial sites within the Dinaric Karst area without taking into account the above-mentioned parameters, require additional measures. This is necessary in order to avoid the pollution of groundwaters and karst springs used for water development.According to field experience and results of investigations, which were recently published, a reliable geotectonic interpretation needed for distinguishing orogenic and epi-oro-genic (epi-platform) karst terranes has usually been missing in analyses of karst morphology. This is important because the karst morphological features different in origin and distribution can be found in both types, respectively.     

Applying size segregation to relate the surrounding aerosol pollution to its source

Size segregated sampling of aerosol particles at the coal-fired power station Šoštanj, Slovenia was performed by a newly developed system. In addition, simultaneous sampling of particles was performed at two locations, Velenje and Veliki vrh, chosen on the basis of long term monitoring of SO₂ in the influential area of power plant. The signature of the power plant (e.g. characteristic size distributions of some typical trace elements) was identified. For elements, like As, Mo, Cd and Ga, which are typical for coal combustion, the highest concentrations were observed in the size range between 1 and 4 μm. For Se and sometimes for Ga two modes were identified, first between 0.1 and 0.5 μm and second between 1 and 4 μm. Ratios between the average concentrations of selected elements in fine and coarse particles collected at Veliki vrh (the most influenced location) and Velenje (usually not influenced by the thermo power station) were significantly higher than 1 in the case of Mo and Se for coarse and fine size range, while for As the ratio was higher than 1 for the coarse fraction. Consequently, Mo, Se and As were found as the most important tracers for the emissions from the investigated source. On the basis of the ratios between the concentrations of elements measured in particles at low and high SO₂ concentrations at Veliki vrh, Cd was shown to be a typical tracer as well. Our results definitely showed that size segregated measurements of particles at the source and in the influenced area give more precise information on the influence of source to the surrounding region. It was found that patterns of size distributions for typical trace elements observed at the source are found also in the influenced area, i.e. Veliki vrh.