Der Oberflächensalzgehalt des Europäischen Mittelmeeres     

Dipl.-Oz. Gerd Axel Becker 《Ocean Dynamics》1978,31(5):190-194

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Die Vergletscherung in Abhängigkeit von Exposition und Höhe und der Gebietsniederschlag im Einzugsgebiet des Pegels Vent in Tirol     

Wendler  Gerd 《Theoretical and Applied Climatology》1967,15(3):260-273

Theoretical and Applied Climatology - Die Vergletscherung (46,0%) im Einzugsgebiet des Pegels Vent (165 km2) wurde in Abhängigkeit von Exposition und Höhe untersucht. Hierbei konnte...  相似文献   

Decadal-scale variations of water mass properties in the deep Weddell Sea   总被引：2，自引：0，他引：2  

Eberhard?FahrbachEmail author  Mario?Hoppema  Gerd?Rohardt  Michael?Schr?der  Andreas?Wisotzki 《Ocean Dynamics》2004,54(1):77-91

Data from cruises between 1989 and 2003 with FS Polarstern were used to construct section-wide potential temperature and salinity time series of the main water masses in the Weddell Gyre. In tandem with these CTD data, two time series between 1989 and 1995 are presented from moored instruments in the central Weddell Sea. The regional and methodological consistency of the dataset allows us to quantify variations which are not visible in less homogeneous datasets. The data reveal significant temperature and salinity variations of the Warm Deep Water and the Weddell Sea Bottom Water on a decadal time scale. The longest time series were obtained at the prime meridian. Here warming is observed in the Warm Deep Water from 1992 to 1998 followed by cooling. In the Weddell Sea proper, measurements of instruments moored in the Weddell Sea Bottom Water layer recorded a temperature increase over 6 years at a rate of 0.01 °C a^–1. After the mooring period, CTD casts in 1998 point to a weakening of the trend. The warming trend in the bottom water occurs over most of the Weddell Sea, as detected in the additional CTD surveys. The variations are close to the detection level in the voluminous Weddell Sea Deep Water. The initial warming trend of the Warm Deep Water is consistent with warming trends reported in literature of subsurface waters of the Antarctic Circumpolar Current. The reversal of the trend in the Weddell Sea seems to be related to variations of the atmospheric conditions which can affect both the intrusion of Circumpolar Deep Water from the north and the circulation of the Weddell Gyre. Because the Warm Deep Water is the major source water for the formation of deep and bottom water in the Weddell Sea, it is suggested that its increase in temperature and salinity is likely to at least partly cause the variations which were observed in the bottom water.Responsible Editor: Jörg-Olaf Wolff  相似文献   

Environmental Copper and Manganese in the Pathophysiology of Neurologic Diseases (Alzheimer's Disease and Manganism)     

Hermann H. Dieter  Thomas A. Bayer  Gerd Multhaup 《洁净——土壤、空气、水》2005,33(1):72-78

Alzheimer's disease (AD) is the most common form of dementia. Populations migrating from developing to industrialized countries seem to elicit a higher incidence and prevalence rate of AD, suggesting lifestyle and environmental factors to have a role in the pathophysiology of AD. One of its major neuropathological hallmarks is the deposition of Aβ peptides as amyloid plaques in the brain of AD patients. Aβ is proteolytically cleaved out of the larger amyloid precursor protein (APP). Cu and Mn are often found in drinking water and may have a neurotoxic potential. APP is involved in Cu homeostasis in mouse and man. In vitro observations and in vivo data obtained from APP mouse models provide strong evidence that APP overexpression enables intracellular Cu to be transported out of the cell. Disturbed metal‐ion homeostasis with elevated serum Cu levels occurs in Alzheimer and Down's patients and lowered levels in post‐mortem AD brain. We observed that bioavailable Cu has specific beneficial effects in an Alzheimer's disease mouse model. This should be regarded as a proof‐of‐concept for a prophylactic approach to overcome the observed CNS Cu deficiency in the brain of Alzheimer's disease patients. Manganism is a disorder with symptoms similar to that of Parkinson's disease. The precise mechanism how manganese can damage the nervous system is unknown. There is some evidence that iron and manganese may utilize similar transport systems. Epidemi ologic data strongly suggests that manganese enters the body primarily via inhalation and through the ingestion of manganese in drinking water.  相似文献   

Inhomogeneity of the Land Surface and Problems in theParameterization of Surface Fluxes in Natural Conditions   总被引：1，自引：0，他引：1  

G. N. Panin  G. Tetzlaff  A. Raabe 《Theoretical and Applied Climatology》1998,60(1-4):163-178

Summary Eddy correlation techniques to determine the turbulent fluxes of heat, moisture and momentum in the near-surface atmospheric layer rely on the Monin-Obukhov similarity theory, which requires stationarity and horizontal homogeneity. Experiments at specially selected sites over land and particularly over sea are used to develop this concept. Recent experiments, deliberately conducted in non-ideal conditions, show an underestimation of turbulent fluxes. Results from the field experiments FIFE, KUREX, TARTEX and SADE, point to a relationship between the underestimation of turbulent fluxes and terrain inhomogeneity. In order to systematically correct for this effect a scheme is suggested which uses fetch lengths of different types of surface in the sites surrounding the environment. In addition, horizontal differences in atmospheric stability above different surfaces are included in the correction scheme. This scheme might be useful for the design of validation experiments in non-homogeneous terrain. Received April 9, 1997 Revised July 16, 1997  相似文献   

Wind Speed Forecasting from 1 to 30 Minutes     

U. Schlink  G. Tetzlaff 《Theoretical and Applied Climatology》1998,60(1-4):191-198

Summary The long lifetime and high intensity of vortex trails generated by landing large-capacity aircraft may cause a risk to subsequently landing planes. A wake vortex warning system can help to avoid such hazards by forecasting the time intervals permitting safe operation on the landing strip. This information provides the basis for an appropriate landing schedule based on reduced succession distances. An essential element of the warning system is the prediction of wind across the landing strip and this is commonly determined by a method based on the principle of persistence. This study shows that autoregressive (AR) modelling can improve the accuracy of crosswind forecasts. To this end, the measurements are analysed in order to estimate model parameters. Unlike the more simplistic previously used method, AR forecasting, as part of the vortex trail warning system, allows longer intervals for safe operation and can avoid forecast discontinuities (leaps) which are inherent problems of all forecasts in which boundary layer processes have to be considered. Received June 10, 1997 Revised October 6, 1997  相似文献   

Deep-sea sediments in the eastern equatorial Atlantic off the African coast and meteorological flow patterns over the Sahel     

Gerd Tetzlaff  Manno Peters 《International Journal of Earth Sciences》1986,75(1):71-79

Deep-sea mineral dust deposits are a powerful tool allowing to deduct atmospheric flow patterns. Here deep-sea sediments from the eastern tropical Atlantic were used to derive climatic conditions over the African continent where in summer the dust is lifted in the transition zone of the Sahara and the Sahel. The meteorological process causing this aeolian dust injection are the squall lines, the rain bearing disturbances of the Sahel. They produce a high surface wind velocity area in their northern vicinity. The deep-sea deposits of sediments and their spatial patterns allowed to conclude that the dust raising mechanism connected with the squall lines were similar for present day conditions and for the time of the last glacial maximum. The Saharan trades and the African monsoon had about the same extension in either time slice coupled with an identical travel belt of the squall lines. However, the intensity and the frequency of the squall lines were lower in glacial times.

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Zusammenfassung Tiefseesedimente liefern interessante und wertvolle Aufschlüsse über atmosphärische Strömungsbedingungen. Hier werden die Sedimente aus dem Gebiet des östlichen tropischen Nordatlantiks verwendet, um klimatische Angaben über die Strömungsverhältnisse über dem afrikanischen Kontinent zu gewinnen, da die Quelle des Staubes auf dem Kontinent im Übergangsbereich zwischen der Sahara und dem Sahel zu suchen ist. Die meteorologische Ursache des systematischen Staubeintrages in die Atmosphäre sind die regenbringenden sommerlichen Störungen des Sahel («>squall lines»<), die in ihrem nördlichen Randbereich ein Gebiet hoher Windgeschwindigkeit am Boden aufweisen, so daß es hier regelmäßig zu Staubaufwirbelungen kommt. Mit Hilfe der räumlichen und zeitlichen Verteilung der Tiefseesedimente konnte schon früher gezeigt werden, daß während der Periode des letzten Hochglazials die Lage der Grenzzone zwischen Passat und afrikanischem Monsun sich im Vergleich zur Gegenwart nicht verändert hat. Hier wird nun zusätzlich deutlich, daß sowohl die Intensität als auch die Frequenz der «>squall lines»< zum Höhepunkt der Vereisung geringer was als heute.

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Résumé Les sédiments amenés par le vent dans les mers profondes fournissent de précieuses indications sur la distribution des courants atmosphériques. Dans cette note, les sédiments de la partie orientale de l'Atlantique tropical sont examinés en vue de déduire les conditions climatiques régnant sur le continent africain, où la source de la poussière est située entre le Sahara et le Sahel. En effet, l'origine météorologique des apports éoliens sont les pertubations pluvieuses (lignes de grains) qui sont accompagnées sur leur bordure nord de vents de grande vitesse au sol. La distribution des sédiments sur le fond océanique a déjà permis de conclure que le mécanisme de transport était, lors de la dernière glaciation (18.000 ans), semblable à ce qu'il est aujourd'hui. Toutefois, l'intensité et la frequence des perturbations étaient plus faibles qu'aujourd'hui.

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. , , , . ("squall lines"), , , . , . , , squall lines .

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The atmospheric transport potential for water vapour and dust in the Sahel region     

Prof. Dr. Gerd Tetzlaff  Manno Peters 《GeoJournal》1986,12(4):387-398

The transport of water vapour and dust in the Sahel can be assigned to identical atmospheric flow systems, the African Easterly Jet, the Easterly Waves and the Squall Lines. The yield of the rainy season in the Sahel depends on the conditions in the preceding rains of the season and is closely coupled to the surface heat budget both in the monsoonal air in the S and the trades in the N. The heat budget, in particular the evaporation after the passage of a Squall Line, is influenced not only by the total amount of preceding rains but also by the plant cover pumping the water to the surface and smoothing the magnitude of the evaporation in time. This feed-back mechanism may be made responsible for the persistence of the Sahel drought as experienced in recent years. The dust export from the African continent towards the Atlantic can only be so effective, because the Squall Lines and the African Easterly Jet are meshed in a way that produces large amounts of suspended material and lifts it to great heights where the transport velocity is very fast.  相似文献   

The influence of tectonically derived relief and climate on the extent of the last Glaciation east of the Patagonian ice fields (Argentina, Chile)     

Gerd Wenzens   《Tectonophysics》2002,345(1-4)

Two large ice fields between 46°30′ and 51°30′S cover the Patagonian Andes. The North and South Patagonian Ice Fields are separated by the transandine depth line at 47°45′ to 48°15′S. Canal and Río Baker run through this depression. The two ice fields are generally considered relics of a continuous ice cap, which covered the entire Patagonian Andes from 39° to 52°S and extended far into the eastern foreland of the Andes. This assumption is not correct for the 200-km-long section of the Andes between Lago Pueyrredón (Lago Cochrane in Chile) (47°15′S) and Lago San Martín (Lago O'Higgins in Chile) (48°45′S). The lack of a continuous ice cap extending far into the east is caused by the transandine depth line, playing a crucial role in the fluvial erosion and the glacial scouring of this tectonic zone. This depression formed a river system (e.g. Río Baker, Río Bravo and Río Mayer) that drains towards the west. Reconstruction of the maximum glacial advance of the last ice age shows that the eastern outlet glaciers of the two ice fields between Lago San Martín and Lago Pueyrredón did not drain towards the east, but rather followed the general gradient of the transandine depth line. In this area the eastern flank of the Andes between Monte San Lorenzo (3770 m) and Sa. de Sangra (2155 m) supported valley glaciers, which were independent of the expanding ice fields. Only a few valley glaciers advanced towards the Patagonian Meseta. The terminal moraines of these glaciers were erroneously interpreted as the eastern edge of a continuous ice cap. North of 47°30′S the outlet glaciers of the NPI advanced 200 km during the LGM and the late glacial advances nearly reached to 71°W. In contrast, south of 49°S glacier expansion was comparatively less: The LGM is situated only 85–115 km east of the present margins of the large outlet glaciers (O'Higgins, Viedma, and Upsala), and no late glacial advance reached 72°W. These considerable differences of glacier expansion were influenced by the northward migration of the westerly precipitation belt during glacial cycles. There is tentative evidence that the glaciers advanced three times in the period from 14 000 to 9 500 ¹⁴C years BP.  相似文献   

Alpine metamorphism of organic matter in metasedimentary rocks from Mt. Medvednica (Croatia)     

Katalin Judik  Gerd Rantitsch  Thomas M. Rainer  Péter Árkai  Bruno Tomljenović 《Swiss Journal of Geoscience》2008,101(3):605-616

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