Were last glacial climate events simultaneous between Greenland and France? A quantitative comparison using non‐tuned chronologies

Several large abrupt climate fluctuations during the last glacial have been recorded in Greenland ice cores and archives from other regions. Often these Dansgaard–Oeschger events are assumed to have been synchronous over wide areas, and then used as tie‐points to link chronologies between the proxy archives. However, it has not yet been tested independently whether or not these events were indeed synchronous over large areas. Here, we compare Dansgaard–Oeschger‐type events in a well‐dated record from southeastern France with those in Greenland ice cores. Instead of assuming simultaneous climate events between both archives, we keep their age models independent. Even these well‐dated archives possess large chronological uncertainties that prevent us from inferring synchronous climate events at decadal to multi‐centennial time scales. If possible, comparisons between proxy archives should be based on independent, non‐tuned time‐scales. Copyright © 2009 John Wiley & Sons, Ltd.     

A GIS based approach to back trajectory analysis for the source apportionment of aerosol constituents and its first application

A new method has been developed to combine back trajectory statistics with a detailed land cover analysis. It provides numeric proxies for the residence times of sampled air masses above certain land cover classes (marine, natural vegetation, agricultural lands, urban areas, and bare areas), as well as further meteorological parameters (mean trajectory length, solar radiation along trajectory, and local height of the boundary mixing layer). The method has been implemented into a GIS-enabled database system to allow for an efficient processing of large datasets with low computational demands. A principal component analysis was performed on a dataset including the modelled residence times, the modelled meteorological parameters, some measured meteorological parameters (wind speed and temperature), and the concentrations of 10 particle constituents (inorganic ions and organic and elemental carbon) in 5 particle size ranges for 29 winter- and summertime samples at an urban background site in Leipzig, Germany. Six principal components could be extracted which together explained about 80% of the total variance in the dataset. The factors could be attributed to the influence of meteorology to continental background pollution, secondary formation processes in polluted air masses, wood burning, aged sea-salt, local traffic, and long-range transported crustal material. The modelled residence times and the meteorological parameters were generally consistent with the existing knowledge of specific particle sources and thereby facilitated and strengthened the interpretation of the factors. Moreover, they allowed for a clear distinction between continental background pollution and secondary formation processes, which has not been possible in previous source apportionment studies. The results demonstrate that the combined usage of back trajectory, land cover, and meteorological data by the presented method yields valuable additional information on the history of sampled air masses, which can improve the quality of source apportionment of atmospheric aerosol constituents.     

Imaging very high energy gamma-ray telescopes

The technique of γ-ray astronomy at very high energies (VHE:>?100 GeV) with ground-based imaging atmospheric Cherenkov telescopes is described, the H.E.S.S. array in Namibia serving as example. Mainly a discussion of the physical principles of the atmospheric Cherenkov technique is given, emphasizing its rapid development during the last decade. The present status is illustrated by two examples: the spectral and morphological characterization in VHE γ-rays of a shell-type supernova remnant together with its theoretical interpretation, and the results of a survey of the Galactic Plane that shows a large variety of non-thermal sources. The final part is devoted to an overview of the ongoing and future instrumental developments.     

CATCHMENT-WIDE ANALYSIS OF THE SEDIMENT REGIME WITH RESPECT TO RESERVOIR SEDIMENTATION

1 INTRODUCTIONIn Anstria reservoirs are frequentiy multi-purpose schemes, being used for power generation, floodprotechon and for wate suPPly downstream. These reservoirs have some adVerse imPaCts on theenvironment around the reservoir and also on the dOwnstream pat:. in rivers with mean annual discharge above 30 m3ls about 36 % of the total length of l884 lQn isimpounded, and only 35% remains as free flowing sections (Muhar, l992),. flooding has been, and continues to be, a serious pr…     

Additive models in mining and exploration

In this paper we present the use of additive models (AMs) for geostatistical applications. AMs are generalizations of linear regression models which hold the central place in the toolbox of applied statisticians. Generally speaking, the linear relationship between response and predictors is replaced with a general functional form. Recently such models were introduced in geostatistics. Especially, we give an approach for binary data. In this case we get generalized additive models (GAMs). Logistic regression is quite popular in medical and biological research. Using logit links also in GAMs we get so called additive logistic models. An application for geostatistical data is introduced. In a second approach we use AMs for spatial prediction and surface modelling. In both cases an advantage of multivariate data can be taken. The proposed applications can be used in the development of exploration strategies, especially in the early stage of exploration     

Die Auswirkungen der Aufstiegszeitänderung 1957 auf die Inversionsstatistik

Zusammenfassung Es werden die Auswirkungen der Verlegung der Sondenaufstiegszeiten im Jahre 1957 auf die Inversionsstatistik gezeigt: Beim Mitternachts- und beim Mittagsaufstieg gibt es mehr Aufstiege mit mehreren gleichzeitigen Inversionen, deren Schichtdicke jedoch meist geringer ist als bei den 3- und 15-Uhr-Aufstiegen. Die Zahl der Bodeninversionen ist zu Mittag kleiner als am Nachmittag, doch treten um 0 und 12 Uhr mehr Aufstiege mit einer Untergrenze unter 1500 m auf. Änderungen der verbundenen Verteilungen von Schichtdicke, Höhe der Untergrenze, Temperatur-differenz zwischen Ober- und Untergrenze und Temperaturgradient betreffen meist nur einzelne Jahreszeiten.

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Summary The effect of the change of sounding-times in 1957 on the statistics of inversions is shown: The soundings at noon and at midnight contain a larger number of ascents with multiple inversions, the thickness of which, however, is smaller than that of the inversions at 3 or 15 hrs. The number of ground inversions is smaller at noon but there are more inversions with a lower boundary below 1500 m at noon and at midnight. Changes of the joint distributions of thickness, height of the lower boundary, temperature differences between upper and lower boundary and temperature gradients mostly concern single seasons only.

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Résumé On a recherché les repercussions qu'a eu le décalage de l'heure des sondages aérologiques sur la statistique des inversions, décalage intervenu en 1957. Lors de sondages effectués à minuit et à midi, on en dénombre davantage qui présentent plusieurs inversions simultanées. L'épaisseur des couches est cependant en général plus faible que dans le cas de sondages faits à 3 heures et à 15 heures. Le nombre des inversions au sol est plus petit à midi que l'après-midi. Pourtant, il y a plus de sondages à 0 heure et 12 heures dont la base de l'inversion se situe au-dessous de 1500 m d'altitude. Les modifications dans la répartition des épaisseurs de couches, de l'altitude de la base, de la différence de température entre la base et le sommet des inversions, ainsi que du gradient thermique ne concernent en général que des saisons restreintes et bien déterminées.

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Mit 3 Textabbildungen     

Quality Assurance of Hydrocarbon Measurements for the German Tropospheric Research Focus (TFS)

In the German Focus on Tropospheric Research (TFS) independent quality assurance procedures were implemented in order to obtain information on data quality and comparability of the different measurements made in the different field campaigns. This paper describes the results for measurements of hydrocarbons using in-situ gas chromatographictechniques and off line analysis of samples collected in canisters (analysed by two central laboratories CL-1 and CL-2) and samples collected on adsorption tubes. The QA-procedures included comparisons with synthetic standards (prepared by EN 45001 certified laboratories), absolute calibration with a diffusion source, and an instrument/methodology comparison in ambient air. Harmonisation of the ambient measurements was achieved with a complex mixture (NCAR/BERLIOZ) containing 70 commonly observed hydrocarbons at mixing ratios of 0.2 to 10 ppb (mole fraction) in nitrogen, which was calibrated by referencing to hydrocarbon standards of the National Institute for Standards and Technology (NIST).For the certified synthetic standards, the experienced groups agreed to within ± 20% for most compounds. Much larger discrepancies were observed for the new Airmotec HC2010 instruments due to problems with identification, co-elution and blanks/memory effects. The results in ambient air were similar: Reasonable agreement was found for the results from the experienced groups with well characterised in situ instruments andfor the charcoal tubes, whereas larger discrepancies were observed for the results from new groups and instruments. For the latter, only selected compounds met the data quality objectives (DQO). The canister samples analysed by CL-2 were in good agreement with the reference instrument, whereas large deviations were found for a number of compounds in the analysis of the same canisters by CL-1. The results of the comparison provided the final basis for flagging and harmonising the data from all participants prior to their submission to the TFS central data bank.     

On recent variations of the annual thunderstorm activity in the region of the Alps

Summary Observations of days with thunderstorm at twelve stations in the Alpine and Pre-Alpine region have been used to look for trends and periodicities in the thunderstorm activity in this area. The annual number of days with thunderstorms was represented by negative binomial distributions, then by means of a non-parametric trend test, parts of the series were found in which the numbers of days with thunderstorm were increasing, decreasing or uniform at the various stations. A variance spectrum analysis showed the existence of long-periodic waves and of short-periodic waves superposed on the background red noise or white noise spectrum. Partitioning the series of observations yielded that these periodicities are not stable.     

Thermal stresses in the modern aircraft

Summary It is proposed for practical purposes to measure the severity of the bioclimate in extreme conditions, as encountered in aircraft, by the tolerance time. The author also suggests a more simple classification of the extreme bioclimates, as shown in Table 1. The probable kind of final fate of a human being in this bioclimate is used for its definition.The air friction causes the temperature of a modern fast airplane to rise in a degree that an equilibrium of temperature is no longer secured. The heat capacity of the cabin, of the clothes, and of the men therefore becomes important for avoiding too high temperatures.A new calculation of observed fast changes of temperature in man yields that the peripheral heat barrier of the body depends upon core temperature and not upon skin temperature. In hot environment the production of heat increases much more than has been supposed.As a consequence of recent experiments of the author about the thermal water loss from the skin the diffusion flow of the insensible perspiration can move in both directions, to and from the skin, according to the vapour pressure of the air; it represents simply the lowest value of osmotic diffusion. The diffusion ressstance of the skin is lowest when it is covered with water. Considerable amounts of water are flowing through the skin from water and solutions; amount and direction of these flows depend upon the concentration of the solutions. When the skin is sweating and exposed to the air the diffusion flow increases with sweating and can reach similar amounts. With a very damp air previously excreted sweat water can return back into the body by diffusion.

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Zusammenfassung Für Zwecke der Praxis wird vorgeschlagen, die Härte des Bioklimas unter extremen Bedingungen, wie sie in der Fliegerei auftreten, nach der Toleranzzeit zu bemessen (Fig. 1). Ferner wird angeregt, statt der verwirrenden Fülle extremer Bioklimate eine Einteilung wie in Tabelle 1 zu benützen. Dabei wird die wahrscheinliche Art des Endschicksals eines Menschen in diesem Bioklima für dessen Definition benutzt.Das moderne Schnellflugzeug wird durch Reibung so stark aufgeheizt, daß Temperaturgleichgewicht nicht mehr erreicht wird. Wärmekapazität von Flugzeugzelle, Kleidung und Mensch werden dadurch zu wichtigen Hilfsmitteln zur Vermeidung zu hoher Temperaturen.Eine Neuberechnung beobachteter schneller Temperaturgänge im Menschen ergibt, daß der periphere Wärmewiderstand des Körpers von der Innentemperatur und nicht von der Hauttemperatur abhängt. In heißer Umgebung steigt die Wärmebildung viel mehr an als bisher angenommen.Nach neuen Versuchen des Verf. über den thermischen Hautwasserverlust kann der Diffusionsstrom der insensiblen Perspiration, je nach dem äußeren Dampfdruck, von der Haut weg oder zu ihr hin gerichtet sein; er stellt nur den untersten Wert der osmotischen Diffusion dar. Der geringste Diffusionswiderstand der Haut findet sich bei Wasserbedeckung. Aus Wasser oder Lösungen fließen erhebliche Wassermassen durch die Haut; Größe und Richtung dieser Ströme richten sich nach der Konzentration der Lösungen. Bei schwitzender, der Luft ausgesetzter Haut nimmt der Diffusionsstrom mit dem Schwitzen zu und kann eine ähnliche Größe erreichen. Bei sehr feuchter Luft kann bereits ausgetretenes Schweißwasser wieder zurückdiffundieren.

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Résumé L'auteur propose, à des fins pratiques, d'évaluer la rigueur d'un bioclimat sous des conditions extrêmes comme on les rencontre dans l'aviation, par le temps de tolérance (fig.1). Il suggère en un tableau une subdivision plus simple des bioclimats extrêmes; pour cela il définit ce climat par le sort final probable de l'organisme humain qui s'y trouve exposé.La chaleur de frottement des avions modernes est telle que l'équilibre de température n'est plus atteint. La capacité calorifique de la cabine d'avion, des vêtements et de l'homme deviennent par conséquent des moyens importants d'éviter des températures trop hautes.Un nouveau calcul de fortes variations de température observées dans l'organisme humain montre que la résistence calorifique du corps dépend de sa température interne et non de celle de la peau. La formation de chaleur augmente par forte chaleur extérieure beaucoup plus qu'on ne l'admettait jusqu'ici.D'après de nouvelles recherches de l'auteur sur la perte calorifique en eau de la peau, le courant de diffusion de la perspiration insensible peut être dirigé vers l'extérieur ou vers l'intérieur, selon la pression de vapeur de l'air; il ne représente que la valeur la plus basse de la diffusion osmotique. La plus petite résistance de la peau à la diffusion s'observe lorsque celle-ci est couverte d'eau. Dans l'eau ou dans une solution, des quantités notables d'eau traversent la peau; la direction et l'importance de ces courants dépendent de la concentration des solutions. Lorsque la peau exposée à l'air transpire, le courant de diffusion augmente avec la transpiration et peut atteindre une grandeur semblable. Dans de l'air très humide, l'eau de transpiration expulsée peut rediffuser vers l'intérieur.

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With 3 Figures.

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Lecture given to the Symposium on Frontiers of man controlled flight. Los Angeles, Cal., April 1953. With the permission of the Institute of Transportation and Traffic Engineering, University of California, Los Angeles.