Der dhaulagiri- und annapurna-himalaya. M. Kuhle,Zeitschrift für Geomorphologie,Suppl.-band 41, Berlin-Stuttgart, 1982     

Gerhard Vorndran 《地球表面变化过程与地形》1983,8(4):405-406

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Holes in the Hα Eruptive Prominence Structure     

Stanislava Šimberová  Marian Karlický  Michal Varady  Gerhard Rank 《Solar physics》2001,201(1):119-131

The eruptive prominence observed on 27 May 1999 in H at Ondejov Observatory is analyzed using image-processing techniques. To understand the physical processes behind the prominence eruption, heated structures inside the cold H prominence material are sought. Two local minima of intensity (holes), the first above and the second below the erupting H prominence, have been found in the processed H images. A comparison of H images with the SOHO/EIT and Yohkoh/SXT images showed: (a) the cold H prominence is visible as a dark feature in the EIT images, (b) the upper local minimum of intensity in the H image corresponds to a hot structure seen in EIT, (c) the lower minimum corresponds to a hot loop observed by SXT. The physical significance of the H intensity minima and their relation to the hot structures observed by EIT and SXT is discussed. The time sequence of observed processes is in favor of the prominence eruption model with the destabilization of the loop spanning the prominence. For comparison with other events the velocities of selected parts of the eruptive prominence are determined.  相似文献   

Ice core evidence for secular variability and 200-year dipolar oscillations in atmospheric circulation over East Antarctica during the Holocene   总被引：3，自引：0，他引：3  

Barbara Delmonte  Jean Robert Petit  Gerhard Krinner  Valter Maggi  Jean Jouzel  Roberto Udisti 《Climate Dynamics》2005,24(6):641-654

Two Holocene ice core records from East Antarctica (Vostok and EPICA-Dome C) were analysed for dust concentration and size distribution at a temporal resolution of 1 sample per ~50 years. A series of volcanic markers randomly distributed over the common part of the ice cores (from 9.8 to 3.5 kyear BP) ensures accurate relative dating (±33 years). Dust-size records from the two sites display oscillations structured in cycles with sub-millennial and secular scale frequencies that are apparently asynchronous. The power spectra of the composite sum (Σ) of the two dust-size records display spectral energy mostly for 150- to 500-year periodicities. On the other hand, the 200-year band is common to both records and the 200 year components of the two sites are out-of-phase (100-year lead or lag) over ~5.5 kyear, a phenomenon also reflected by a significant (>99% conf. lev.) band in the power spectra of the composite difference (Δ) of the two size records. During long-range transport, mineral dust originating from the Southern Hemisphere continents is graded to a variable extent depending on the altitude and duration of atmospheric transport. Relatively coarse dust is associated with air mass penetration from the middle–lower troposphere and conversely relatively fine dust with upper troposphere air masses or the influence of subsidence over the Antarctic plateau, a hypothesis already proposed for the changes that occurred during the Last Glacial Maximum to Holocene transition (Delmonte et al. 2004b). Moreover, we assume that the overall fluctuation of air mass advection over Antarctica depends on the meridional pressure gradient with respect to low latitudes, i.e. the Antarctic Oscillation (AAO). We therefore suggest a regional variability in atmospheric circulation over East Antarctica. The 150–500 year power spectrum of the composite (Σ) parameter represents the long term variability of the AAO, imprinted by secular internal oscillations probably related to the southern ocean-climatic system. On the other hand, the Δ dust composite parameter suggests a persistent atmospheric dipole over East Antarctica delivering coarser (finer) dust particles alternatively to Vostok and Dome C regions with a bi-centennial periodicity. Indeed, a seesaw phenomenon in dust size distribution was already observed at three East Antarctic sites during the last deglaciation (Delmonte et al. 2004b) and was interpreted as a progressive reduction of the eccentricity of the polar vortex with respect to the geographic south pole. Interestingly, the Δ parameter shows a pronounced 200-year oscillation mode, throwing new light on the unresolved question of a possible relationship between climate and solar activity.  相似文献   

The development of computer networks: First results from a microeconomic model     

Gunther Maier  Alexander Kaufmann 《Journal of Geographical Systems》2001,3(2):155-166

 Computer networks like the Internet are gaining importance in social and economic life. The accelerating pace of the adoption of network technologies for business purposes is a rather recent phenomenon. Many applications are still in the early, sometimes even experimental, phase. Nevertheless, it seems to be certain that networks will change the socioeconomic structures we know today. This is the background for our special interest in the development of networks, in the role of spatial factors influencing the formation of networks, and consequences of networks on spatial structures, and in the role of externalities. This paper discusses a simple economic model – based on a microeconomic calculus – that incorporates the main factors that generate the growth of computer networks. The paper provides analytic results about the generation of computer networks. The paper discusses (1) under what conditions economic factors will initiate the process of network formation, (2) the relationship between individual and social evaluation, and (3) the efficiency of a network that is generated based on economic mechanisms. Received: 5 July 2000 / Accepted: 28 November 2000  相似文献   

The world''s large lake basins as denudation-accumulation systems and implications for their lifetimes     

Matthias Hinderer  Gerhard Einsele 《Journal of Paleolimnology》2001,26(4):355-372

The mechanical denudation rates of 81 large lake basins (lake area > 500 km²) were determined from long-term river loads and erosion maps. Using the drainage area/lake area ratios the mean sedimentation rates of the lakes were calculated for a porosity of 0.3. The mean sedimentation rates of different lake types vary between 0.1 mm/a (glacial lakes, lowland) and 5.4 mm/a (mostly sag basin lakes). The calculated lifetimes of the lakes are based on the lake volumes and mean sedimentation rates, assuming steady-state conditions and solely clastic material. On average, glacial lakes in highlands and fault-related lakes show the shortest lifetimes (c. 70 ka), glacial lakes in lowlands and rift lakes have the longest lifetimes (c. 1 Ma). Some lakes remain unfilled for very long time spans due to rapid subsidence of their basin floors. The calculated lifetimes are compared with those derived from sediment core studies. Most core studies indicate lower mechanical sedimentation rates than the calculated ones because a major part of the incoming sediment is trapped in deltas. However, a number of lakes (e.g., the Great Lakes of North America) show the opposite tendency which is largely caused by extensive shoreline erosion and resuspension. The lifetimes of large glacial lakes often exceed the duration of interglacials. Hence, their lifetimes are restricted by glaciation and not by sediment infill. Rift lakes persist for long time periods which exceed the calculated lifetimes in some cases. Time-dependent subsidence, basin extension, as well as the impact of climate change are briefly described.  相似文献   

Auswirkungen des Ablassens von Hochwasserrückhaltebecken auf deren Limnochemie und Phytoplankton-Biozönose     

Susanne Maier  Klaus Zintz  Jürgen Bhmer  Petra Sterk  Hinrich Rahmann 《Limnologica》2001,31(3):239

Reservoirs have to be released when repairing of the dams is necessary. In 1995, two reservoirs in Baden-Württemberg (Germany) of similar age and volume (Lake Herrenbach near Göppingen, 1.0 Mio. m³ and Lake Breitenau near Heilbronn, 2.3 Mio. m³) were emptied. This allowed the singular possibility to investigate the effects of drainage and refilling on the limnochemistry and the phytoplankton biocoenosis of such artificial lakes.Before the drainage of the reservoirs, both lakes showed phosphorus release from the sediment during summer stagnation. Phosphorus values of Lake Herrenbach were regularly higher than those of Lake Breitenau (Lake Herrenbach 88 μg/l, Lake Breitenau 33 μg/l). During release, both lakes indicated higher phosphorus and chlorophyll concentrations as well as rising biomasses. Remarkable differences were observed during refilling of the reservoirs: while Lake Herrenbach showed higher transparency and lower phosphorus concentrations, Lake Breitenau progressed towards eutrophication (total phosphorus during summer 1996: Lake Herrenbach 30 μg/l, Lake Breitenau 55 μg/l). One reason for the reaction of Lake Breitenau was the reduced ground drainage during the refilling, which caused an accumulation of nutrients in the hypolimnion. Another reason was the mineralisation of vegetation which covered great parts of the dry lake sediment. The limnological change of Lake Herrenbach was not as clear but could be caused by the restauration of the pre-reservoir which was drainaged and dredged before the emptying of the main reservoir started as well as many other facts which differed Lake Herrenbach from Lake Breitenau.  相似文献   

Location and height of intertidal bars on macrotidal ridge and runnel beaches     

Gerhard Masselink  Edward J. Anthony 《地球表面变化过程与地形》2001,26(7):759-774

Previous studies devoted to the morphology and hydrodynamics of ridge and runnel beaches highlight characteristics that deviate from those initially postulated by King and Williams (Geographical Journal, 1949, vol. 113, 70–85) and King (Beaches and Coasts, 1972, Edward Arnold). Disagreements on the morphodynamics of these macrotidal beaches include the position of the ridges relative to the mean neap and spring tide levels, the variation in the height of the ridges across the intertidal profile and, most importantly, whether the ridges are formed by swash or surf zone processes. The morphological characteristics of ridge and runnel beaches from three locations with varying wave, tidal and geomorphic settings were investigated to address these disagreements. Beach profiles from each site were analysed together with water‐level data collected from neighbouring ports. It was found that the ridges occur over the entire intertidal zone. On one site (north Lincolnshire, east England), the ridges are uniformly distributed over the intertidal beach, whereas on the two other sites (Blackpool beach, northwest England, and Leffrinckoucke beach, north France) there is some indication that the ridges appear to occur at preferential locations. Most significantly, the locations of the ridge crests were found to be unrelated to the positions on the intertidal profile where the water level is stationary for the longest time. It was further found that the highest ridges generally occur just above mid‐tide level where tidal non‐stationarity is greatest. These findings argue against the hypothesis that the ridges are formed by swash processes acting at stationary tide levels. It is tentatively suggested that the ridges are the result of a combination of swash and surf zone processes acting across the intertidal zone. Elucidation of the morphodynamic roles of these two types of processes, and other processes such as strong current flows in the runnels, requires further comprehensive field measurements complemented by numerical modelling. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Editorial     

Gerhard Furrer  Bernhard Wehrli  Heinz Gamsjäger 《Aquatic Sciences - Research Across Boundaries》1993,55(4):229-229

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Röntgenographische Gefügeanalyse mit dem Texturgoniometer am Beispiel von Quarziten aus kaledonischen Überschiebungszonen     

Dr. Kurt v. Gehlen  Dr. Gerhard Voll 《International Journal of Earth Sciences》1962,51(2):440-450

Zusammenfassung Quantitative Gefügediagramme können röntgenographisch mit einem Zählrohr-Textur-Goniometer gemessen werden. Diese Methode kommt besonders in Frage bei sehr feinkörnigen Gesteinen oder aber dann, wenn etwa bei einachsigen Mineralen auch die Regelung anderer Gitterrichtungen außer der c-Achsen-Richtung interessiert. Das beim Quarz anzuwendende Verfahren wird behandelt und gezeigt, wie man hier im Einzelfall Prismenregelungen nachweisen kann. Als praktische Beispiele werden Quarzitgefüge mit Prismenregelung aus kaledonischen Überschiebungszonen Schottlands und Norwegens abgebildet und ihre Entstehung diskutiert. Die Messungen scheinen darauf hinzuweisen, daß beim Quarz bevorzugt Translation mit (11¯20) als Gleitfläche und c als Gleitgerade maßgebend war.  相似文献   

Nachweis einer fortschreitenden Welle in der südlichen Nordsee     

Gerhard Tomczak 《Ocean Dynamics》1958,11(3):97-109

Zusammenfassung Am 4. November 1957 wurde an den deutschen und niederländischen Küsten der Nordsee eine Störung des Gezeitenverlaufes beobachtet. Trotz eines Sturmes aus ablandiger Richtung wurde der mittlere Wasserstand bis zu mehreren Metern erhöht. Eine Analyse der Wasserstandsbeobachtungen von vierzehn Stationen ergab, daß es sich um eine fortschreitende Welle handelte, die sich im Seegebiet der südwestlichen Nordsee gebildet hatte. Es wird die Entstehung dieser Welle untersucht. Sie wird erklärt 1. aus ungewöhnlich stark ausgeprägten Luftdruckschwankungen im Küstengebiet Südostenglands und 2. aus dem besonderen Windfeld im Bereich eines Tiefdrucktroges über der südwestlichen Nordsee. Die beobachteten Durchgangszeiten der Welle stimmen mit den berechneten Werten überein; auch die beobachteten Amplituden lassen sich größenordnungsmäßig erklären. Ein Parallelfall vom 13./14. Dezember 1956 weist schließlich auf die Ähnlichkeit der Erscheinung mit den an der englischen Ostküste häufiger beobachtetenexternal surges hin, die als fortschreitende Wellen vom Atlantischen Ozean her in die Nordsee vordringen.

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Verification of a progressive wave in the southern North Sea

Summary On November 4, 1957, a disturbance of the tide was observed on the German and Netherlandish North Sea coasts. Although a storm associated with offshore winds was dominating, the water rose up to several meters above mean sea level. The analysis of sea level observations from 14 stations showed that the rise of water was due to a progressive wave that had been produced in the sea region of the southwestern North Sea. The origin of the progressive wave is the subject of the present investigations. Its occurrence is attributed firstly to atmospheric pressure variations of extraordinary intensity over the southeastern coastal area of England, secondly to a particular wind field in the neighbourhood of a trough of low pressure over the southwestern North Sea. The observed times of passage of the progressive wave correspond to the calculated values; the order of magnitude of the observed amplitudes, too, allows a satisfactory interpretation. A parallel case occurring on December 13/14, 1956 reveals the resemblance of the progressive wave to the phenomenon of external surges, frequently observed on the east coast of England; taking its origin as a progressive wave in the Atlantic Ocean, it penetrates into the North Sea.

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Preuve de la présence d'une onde progressive dans la région sud de la mer du Nord

Résumé Le 4 novembre 1957, on observa une perturbation de la marée sur la côte allemande et sur la côte néerlandaise. Bien qu'une tempête, associée aux vents de terre, dominât, la surface de la mer atteignit une hauteur supérieure au niveau moyen de la mer de plusieurs mètres. Une analyse basée sur des observations du niveau de la merde 14 stations révéla qu'il s'agit d'une onde progressive originaire de la région sud-ouest de la mer du Nord. La génération de cette onde est le sujet des recherches actuelles. Sa formation est ramenée 1⁰ aux variations extraordinairement prononcées de pression atmosphérique au-dessus du littoral sud-est de l'Angleterre, et 2⁰ au champ particulier du vent au voisinage d'un couloir de basse pression au-dessus de la région sud-ouest de la mer du Nord. Les observations des heures de passage de l'onde progressive s'accordent avec les valeurs calculées; de même, l'ordre de grandeur des amplitudes observées permet une interprétation satisfaisante. Un cas analogue, survenu le 13/14 décembre 1956, révéla enfin la ressemblance de l'onde progressive avec le phénomène des ondes externes («external surges») observées fréquemment sur la côte est de l'Angleterre; ce type d'onde tire son origine dans l'Océan Atlantique pour pénétrer dans la mer du Nord.

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Dank. Diese Untersuchung wurde ermöglicht, weil verschiedene Dienststellen entgegenkommenderweise Beobachtungsmaterial zur Verfügung stellten: Die Wasser- und Schifffahrtsämter Emden, Wilhelmshaven, Bremerhaven, Cuxhaven und Tönning sowie die Marschenbauämter Heide und Husum stellten ihre Pegelaufzeichnungen zur Verfügung, der Rijkswaterstaat, 's-Gravenhage, die der niederländischen Stationen. Die englischen und niederländischen Luftdruckbeobachtungen wurden mir freundlicherweise von Mr. Virgo, Chief Meteorological Officer, Headquarters Second ATAF, und Herrn M. P. H. Weenink, De Bilt, vermittelt. Das Seewetteramt Hamburg des Deutschen Wetterdienstes stellte wiederum, wie schon bei früheren Untersuchungen, bereitwillig die Arbeitswetterkarten zur Einsicht zur Verfügung. Schließlich sei dankend hervorgehoben, daß die im internationalen Wetterfernschreibnetz verbreiteten Wasserstandsbeobachtungen des englischen Sturmflutwarndienstes die Untersuchung wesentlich gefördert haben.  相似文献