Hydrometeorologische Ergebnisse aus Abflußmessungen im Bereich des Hintereisferners (Ötztaler Alpen) in den Jahren 1957 bis 1959

Zusammenfassung Während der Internationalen Geophysikalischen Jahre 1957 bis 1959 wurde an einer Pegelmeßstelle bei 2287 m Höhe der Abfluß vom Hintereis- und Kesselwandferner registriert. Im vorliegenden Arbeitsbericht sollen spezifischen Merkmale des Abflusses aus dem zu 58% vergleitscherten Einzugsgebiet 26,6 km²) im Zusammenhang mit den meteorologischen Beidingungen dargestellt werden.Der Jahresabfluß betrug im Haushaltsjahr 1957/58 1848 mm und im Haushaltsjahr 1958/59 1770 mm; bedingt durch den stark negative massenhaushat der Gletscher was die Gletscherspende mit 24% bzw. 20% des Jahresabflusses außergewöhnlich hoch. Der winterabfluß (Oktober bis März) betrug nur 5% bzw. 10% des Jahresabflusses; die drei Sommermonate Juli bis September Lieferten dagegen 76% bzw. 72%. Der größte Monatsabfluß wurde im August 1958 mit 575 mm, im Juli 1959 mit 559 mm registriert.Die Häufigkeitsverteilung der Tagesabflußmengen für das Jahr 1957/58 ließ eine Andauer des Niedrigwassers mit Tages-Mittelwerten kleiner als 18,8 l/s km² (0,5 m³/s) von 217 Tagen (Oktober bis Mai, 59% des Jahres) erkennen. Größere Tagesabflüsse als 225 l/s km² (6,0 m³/s) kamen nur im Juli und August vor. Als Maximum wurden Abflußwerte bis zu 640 l/s km² Gletscherfläche im Tagesmittel erreicht, entsprechen 55m Abflußhöhe von den Schnee- und Eisflächen. Der exponentielle Abfall der Abflußganglinie vom Herbst zum Minimum im Frühjahr deutet an, daß es sich bei Winterwasser vorwiegend um das verzögerte Abfließen von in den Gletschern zurückgehaltenem Schmelzwasser aus der vorangegangenen Ablationsperiode handelt. Das Ansteigen der Wasserführung nach dem Beiginn der Schneeschmelze im Frühjahr erfolgt wegen des Wiedergefrierens von Schmelzwasser und wegen des Retentionsvermögens der Schneedecke mit einiger Verzörgerung.Die unperiodischen Schwankungen im Abflußgang stehen in engem Zusammenhang mit Wettervorgängen, wobei Schneeniederschlägen die Größte Bedeutung zukommt, weil die hohe Albedo einer Neuschneedecke die Ablation auf den Gletschern tagelang fast völlig unterbrechen kann. Aus zweistündigen Mittelwerten wurde für die Monate Juni bis September der mittlere Tagesgang der Wasserführung ermittelt. Die Ursache für das frühere Eintreten des taglichen Abflußmaximums im Spätsommer durfte verminderte Abflußverzögerung sein. Die Beziehung zwischen den Abflußwerten der Pegel Steg-Hospiz und Vent läßt einen Jahresgang erkennen.

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Summary During the International Geophysical Years 1957–1959 the run-off from Hintereisferner and Kesselwandferner was recorded by a stream gauge installed at an altitude of 2287 m. a. s. 1. The annual run-off in relation to mass budget and precipitation has already been reported in [10, 11]. In the present report characteristic features of run-off from a catchment area (26.6 km²) glaciated to 58 per cent shall be discussed with regard to the meteorological conditions.In the budget years 1957/58 and 1958/59 the yearly run-off was 1848 mm and 1770 mm, respectively. Owing to the strongly negative mass budget of the glaciers the glacier quota of 24 per cent and of 20 per cent, respectively, of the annual run-off was exceptionally high. Winter run-off (October to March) amounting to 5 per cent and to 10 per cent, respectively, of the yearly run-off was only small while July to September supplied 76 per cent and 72 per cent, respectively. The maximum monthly run-off was recorded in August 1958 with 575 mm, and in July 1959 with 559 mm.The frequency distribution of the daily run-off in 1957/58 showed a period of low run-off during 217 days (October to May, 59 per cent of the year) with daily means below 18.8 l/s km² (0.5 m³/s). Daily run-off exceeding 225 l/s km² (6.0 m³/s) occurred only in July and August. Daily means exceeding 338 l/s km² (9.0 m³/s) were recorded only three times in July. The maximum daily means of run-off were up to 640 l/s km² of glacier surface which corresponds to 55 mm of run-off from the snow and ice surfaces. The highest two hourly mean value was 950 l/s km² of the glacier surface. The exponential decrease of the run-off curve from fall to the minimum in spring indicates that winter water consists mainly of the delayed run-off of melt water stored in the glaciers during the preceding ablation period. Owing to the refreezing of the melt water and to the storage capacity of the snow cover run-off is somewhat delayed after the snow melt has set in.The aperiodic variations in the run-off are closely related to weather conditions. Snow falls are of primary importance as the high albedo of a fresh snow cover may interrupt ablation on glaciers almost completely for days. The mean daily variation of run-off was determined from two-hourly mean values for the period June to September. The early occurrence of the daily run-off. The relation between the run-off values recorded at the water gauges Steg-Hospiz and Vent indicates and annual variation.

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Résumé Pendant les Années Géophysiques Internationales de 1957 à 1959 l'écoulement du Hintereisferner et du Kesselwandferner a été enregistré par un limnigraphe installé à une altitude 2287 m. Un rapport a déjà été présenté dans [10, 11] sur l'écoulement annuel en rapport avec le bilan hydrologique du bassin. Dans le présent rapoort il sera traité des caractères spécifiques de l'écoulement d'un bassin dont 58% sont recouverts par le glacier, les quels seront mis en rapport avec les conditions météorologiques.L'écoulement annuel au cours de l'année hydrologique 1957/58 a été de 1848 mm et dans l'année hydrologique 1958/59 de 1770 mm. L'eau libérée par la perte de substance glacière représente 24% pour 1957/58 et 20% pour 1958/59 de l'écoulement annuel. Les pourcentages extrêmement élevés doivent être attribués au bilan fortement négatif des glaciers. L'écoulement d'hiver (Octobre à Mars) représentant 5% pour l'année 1957/58 et 10% pour 1958/59 de l'écoulement annuel a été petit tandis que les trois mois d'été (Juillet–Septembre) fournissaient 76% (1957/58) et 72% (1958/59). L'écoulement mensuel le plus élevé a été enregistré en Aôut 1958 avec 575 mm, et, en Juillet 1959 avec 559 mm.La répartition des fréquences des écoulements journaliers pour l'année 1957/58 indique une période d'étiage de 217 jours (Octobre à Mai, 59% de l'année) avec valeurs journalières en dessous de 18.8 l/s km² (0.5 m³/s). Des écoulements dépassant 225 l/s km² (6.0 m³/s) n'ont été enregistrés qu'en Juillet et Aôut. Les moyennes journalières n'ont dépassé les 338 l/s km² (9.0 m³/s) que trois fois en Juillet. Les valeurs maximums des moyennes journalières d'écoulement se sont élevées à 640 l/s km² de la surface des glaciers, correspondant à 55 mm d'écoulement des surfaces de neige et de glace. La valeur maximum d'une moyenne de deux heures a été de 950 l/s km² de la surface des glaciers. La chute exponentielle de la courbe d'écoulement allant de l'automne au minimum enregistré au printemps indique que dans les cas d'étiage il s'agit de l'écoulement retardé des aux de fonte refenues dans les glaciers pendant la période d'ablation précédente. L'accroissement de l'écoulement après le comencement de la fonte de neige au printemps est retardé dans une certaine mesure par le regel des aux de fonte et la capacité de rétention de la couche de neige. Les variations apériodiques dans l'écoulement sont en relations étroites avec les conditions atmospheriques dont les chutes de neige sont de la plus grade importance car l'albédo élevé d'une couche de neige fraîche interrompt parfois et presque complétement l'ablation sur les glaciers pour des jours entiers.L'amplitude moyenne de la variation journalière de l'écoulement a été, pour les mois de Juin à Septembre, détérminée à la base des valeurs moyennes de deux heures. L'apparition précoce du maximum d'écoulement journalier en fin d'été est probablement due à la diminution du retardement de l'écoulement en cette période. La relation entre le valeurs d'écoulement des limnigraphes de Steg-Hospiz et de Vent met en évidence une variation annuelle.

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Die für diesen Bericht erforderliche weitere Bearbeitung der Abflußdaten und die Fertigstellung des Manuskriptes wurde dem Verfasser im Rahmen seiner Tätigkeit bei der Kommission für Glaziologie an der Bayerischen Akademie der Wissenschaften ermöglicht, wofür an dieser Stelle gedankt sei.     

Diurnal changes in the bio-optical properties of the phytoplankton in the Alborán Sea (Mediterranean Sea)

The changes in the phytoplankton absorption properties during a diurnal cycle were investigated at one station located in the north-western area of the Alborán Sea. The experiment was performed in spring when the water column was strongly stratified. This hydrological situation permitted the establishment of a deep chlorophyll a (chl a) fluorescence maximum (DFM) which was located on average close to the lower limit of the mixed layer and the nutricline. The relative abundance of pico-phytoplankton (estimated as its contribution to the total chl a) was higher in the surface, however, micro-phytoplankton dominated the community at the DFM level. Chl a specific absorption coefficient (a*(λ)) also varied with optical depth, with a* (the spectrally average specific absorption coefficient) decreasing by 30% at the DFM depth with respect to the surface. A significant negative correlation between the contribution of the micro-phytoplankton to the total chl a and a* was obtained indicating that a* reduction was due to changes in the packaging effect. Below the euphotic layer, a* increased three-fold with respect to the DFM, which agrees with the expected accumulation of accessory pigments relative to chl a as an acclimation response to the low available irradiance. The most conspicuous change during the diurnal cycle was produced in the euphotic layer where the chl a concentration decreased significantly in the afternoon (from a mean concentration of 1.1 μg L⁻¹ to 0.7 μg L⁻¹) and increased at dusk when it averaged 1.4 μg L⁻¹. In addition, a* and the blue-to-red absorption band ratio increased in the afternoon. These results suggest that a*(λ) diurnal variability was due to increase in photo-protective and accessory pigments relative to chl a. The variation ranges of a*(λ) at 675 and 440 nm (the absorption peaks in the red and blue spectral bands, respectively) in the euphotic layer were 0.01–0.04 and 0.02–0.10 m² mg⁻¹ chl a, respectively. Approximately 30% out of this variability can be attributed to the diurnal cycle. This factor should therefore be taken into account in refining primary production models based on phytoplankton light absorption.     

JECSS news no. 7 R/V Akademik Korolyev,nautical archaeology,ts-ts meander,oki island-canyon system

JECSS news no. 7 R/V Akademik Korolyev, nautical archaeology, ts-ts meander, oki island-canyon system     

A Zonal Pathway for NADW in the South Atlantic

Several large deployments of neutrally buoyant floats took place within the Antarctic Intermediate (AAIW), North Atlantic Deep Water (NADW), and the Antarctic Bottom Water (AABW) of the South Atlantic in the 1990s and a number of hydrographic sections were occupied as well. Here we use the spatially and temporally averaged velocities measured by these floats, combined with the hydrographic section data and various estimates of regional current transports from moored current meter arrays, to determine the circulation of the three major subthermocline water masses in a zonal strip across the South Atlantic between the latitudes of 19°S and 30°S. We concentrate on this region because the historical literature suggests that it is where the Deep Western Boundary Current containing NADW bifurcates. In support of this notion, we find that a net of about 5 Sv. of the 15–20 Sv that crosses 19°S does continue zonally eastward at least as far as the Mid-Atlantic Ridge. Once across the ridge it takes a circuit to the north along the ridge flanks before returning to the south in the eastern half of the Angola Basin. The data suggest that the NADW then continues on into the Indian Ocean. This scheme is discussed in the context of distributions of dissolved oxygen, silicate and salinity. In spite of the many float-years of data that were collected in the region a surprising result is that their impact on the computed solutions is quite modest. Although the focus is on the NADW we also discuss the circulation for the AAIW and AABW layers.     

Environmental consequence analyses of fish farm emissions related to different scales and exemplified by data from the Baltic--a review

The aim of this work is to review studies to evaluate how emissions from fish cage farms cause eutrophication effects in marine environments. The focus is on four different scales: (i) the conditions at the site of the farm, (ii) the local scale related to the coastal area where the farm is situated, (iii) the regional scale encompassing many coastal areas and (iv) the international scale including several regional coastal areas. The aim is to evaluate the role of nutrient emissions from fish farms in a general way, but all selected examples come from the Baltic Sea. An important part of this evaluation concerns the method to define the boundaries of a given coastal area. If this is done arbitrarily, one would obtain arbitrary results in the environmental consequence analysis. In this work, the boundary lines between the coast and the sea are drawn using GIS methods (geographical information systems) according to the topographical bottleneck method, which opens a way to determine many fundamental characteristics in the context of mass balance calculations. In mass balance modelling, the fluxes from the fish farm should be compared to other fluxes to, within and from coastal areas. Results collected in this study show that: (1) at the smallest scale (<1 ha), the "footprint" expressing the impact areas of fish cage farm often corresponds to the size of a "football field" (50-100 m) if the annual fish production is about 50 ton, (2) at the local scale (1 ha to 100 km2), there exists a simple load diagram (effect-load-sensitivity) to relate the environmental response and effects from a specific load from a fish cage farm. This makes it possible to obtain a first estimate of the maximum allowable fish production in a specific coastal area, (3) at the regional scale (100-10,000 km2), it is possible to create negative nutrient fluxes, i.e., use fish farming as a method to reduce the nutrient loading to the sea. The breaking point is to use more than about 1.1 g wet weight regionally caught wild fish per gram feed for the cultivated fish, and (4) at the international scale (>10,000 km2) related to the Baltic Proper, the contribution from fish farms to the overall nutrient fluxes are very small. We have also given two case-studies at the local scale where the impact of the fish farm emissions are greatest and the idea is to identify coastal areas unsuitable and suitable for fish cage farms and the reasons why. It should also be stressed that the results presented here are exemplified using emissions from fish farms, but that the underlying principles to evaluate the ecosystem effects of nutrient discharges from point source emissions are valid in a wider and more general perspective.     

Zircon M257 ‐ a Homogeneous Natural Reference Material for the Ion Microprobe U‐Pb Analysis of Zircon

We introduce and propose zircon M257 as a future reference material for the determination of zircon U‐Pb ages by means of secondary ion mass spectrometry. This light brownish, flawless, cut gemstone specimen from Sri Lanka weighed 5.14 g (25.7 carats). Zircon M257 has TIMS‐determined, mean isotopic ratios (2s uncertainties) of 0.09100 ± 0.00003 for ²⁰⁶pb/²³⁸U and 0.7392 ± 0.0003 for ²⁰⁷pb/²³⁵U. Its ²⁰⁶pb/²³⁸U age is 561.3 ± 0.3 Ma (unweighted mean, uncertainty quoted at the 95% confidence level); the U‐Pb system is concordant within uncertainty of decay constants. Zircon M257 contains ～ 840 μg g^?1 U (Th/U ～ 0.27). The material exhibits remarkably low heterogeneity, with a virtual absence of any internal textures even in cathodoluminescence images. The uniform, moderate degree of radiation damage (estimated from the expansion of unit‐cell parameters, broadening of Raman spectral parameters and density) corresponds well, within the “Sri Lankan trends”, with actinide concentrations, U‐Pb age, and the calculated alpha fluence of 1.66 × 10¹⁸ g^?1. This, and a (U+Th)/He age of 419 ± 9 Ma (2s), enables us to exclude any unusual thermal history or heat treatment, which could potentially have affected the retention of radiogenic Pb. The oxygen isotope ratio of this zircon is 13.9%o VSMOW suggesting a metamorphic genesis in a marble or calc‐silicate skarn.     

The Glarus thrust: excursion guide and report of a field trip of the Swiss Tectonic Studies Group (Swiss Geological Society, 14.–16. 09. 2006)

This excursion guide results form a field trip to the Glarus nappe complex organized by the Swiss Tectonic Studies Group in 2006. The aim of the excursion was to discuss old and recent concepts related to the evolution of the Glarus thrust. The major aspects were (i) the interplay between deformation, fluid flow and geochemical alteration, (ii) episodic versus continuous deformation and fluid flow, and (iii) the link between large-scale structures, microstructures, and geochemical aspects. Despite 150 years of research in the Glarus nappe complex and the new results discussed during the excursion, there exist controversies that still are unsolved.     

Noise storms and the structure of microwave emission of solar active regions

Solar radio and microwave sources were observed with the Very Large Array (VLA) and the RATAN-600, providing high spatial resolution at 91 cm (VLA) and detailed spectral and polarization data at microwave wavelengths (1.7 to 20 cm - RATAN). The radio observations have been compared with images from the Soft X-ray Telescope (SXT) aboard theYohkoh satellite and with full-disk phoptospheric magnetic field data from the Kislovodsk Station of the Pulkovo Observatory. The VLA observations at 91 cm show fluctuating nonthermal noise storm sources in the middle corona. The active regions that were responsible for the noise storms generally had weaker microwave emission, fainter thermal soft X-ray emission, as well as less intense coronal magnetic fields than those associated with other active regions on the solar disk. The noise storms did, however, originate in active regions whose magnetic fields and radiation properties were evolving on timescales of days or less. We interpret these noise storms in terms of accelerated particles trapped in radiation belts above or near active regions, forming a decimetric coronal halo. The particles trapped in the radiation belts may be the source of other forms of nonthermal radio emission, while also providing a reservoir from which energetic particles may drain down into lower-lying magnetic structures.Presented at the CESRA-Workshop on Coronal Magnetic Energy Release at Caputh near Potsdam in May 1994.     

La Formation glaciaire de la Mambéré (République Centrafricaine): Reconstitution paléogéographique et implications à l'échelle du Paléozoique africain

The Mambéré Formation constitutes a horizontal unit located in the western and southwestern part of the Central African Republic. Stratigraphical and sedimentological study provides strong argument to attribute these deposits a glacial origin. A palaeogeographical reconstruction has been outlined in order to precise the age of the formation. Two main categories of glacial deposits have been recognized:

glaciogenic deposits made of basal tills (with facetted pebbles) and flow tills (with flattened blunt pebbles);

reworked glacial deposits formed of sandstones and conglomeratic sandstones, in continuous beds, lenses or isolated blocks, together with siltstones and bedded sandstones.

The southerly provenance of the detrital material is demonstrated by quartz grain surface analysis and heavy-mineral study. This material results essentially from the dismantling of the Precambrian Schistoquartzitic Complex and secondarily from the Granitogneissic Complex. According to the palaeomagnetic polar paths and the migration of the glacial centers over the African continent during the Palaeozoic, the Mambéré Formation may be attributed a Lower Silurian age by reference to similar formations observed in Cameroon or a Lower Carboniferous age by comparison with the glacial formations reported from Niger and Egypt.