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1.
An attempt to resolve non-uniqueness in the interpretation of transient electromagnetic (TEM) sounding data using measured data alone is made. It is shown in the various examples studied that sufficiently early time measurements can be the determining factor in reducing the ambiguity caused by model equivalence. The early delay times thus play a dual role in transient soundings: they are responsible for resolving shallow structures and they may eliminate the ambiguity in the interpretation of geoelectric parameters of deeper targets. This is illustrated by the results of a follow-up TEM survey at the Dead Sea coast of Israel where the use of supplementary early time measurements allowed non-uniqueness in the determination of the depth to fresh/saline groundwater interface to be resolved. 相似文献
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Surface energy balance measurements at a tropical site in West Africa during the transition from dry to wet season 总被引：1，自引：0，他引：1
M. Mauder O. O. Jegede E. C. Okogbue F. Wimmer T. Foken 《Theoretical and Applied Climatology》2007,89(3-4):171-183
Summary In one of the first micrometeorological experiments at a tropical site in West Africa, direct measurements of all surface
energy balance components were carried out. The experiment NIMEX-1 in Ile-Ife, Nigeria (7°33′ N, 4°33′ E), was conducted from
February 19, 2004 to March 9, 2004, during the transition from the dry to the wet season. Three typical weather situations
could be observed: firstly, monsoonal winds from the southwest blew over desiccated soils. Almost 100% of the available energy
at the surface was transformed into sensible heat flux. Secondly, after several thundershowers, monsoonal winds swept over
soils of increased water content, which led to a partitioning of the available energy corresponding to Bowen ratios between
0.3 and 0.5. Thirdly, harmattan winds advected dry dusty air from northern directions, which reduced the incoming shortwave
radiation. Again, Bowen ratios range from 0.3 to 0.5 during daytime, whereas latent heat fluxes are still high during the
night due to the advection of very dry air. No systematic non-closure of the surface energy balance could be found for the
NIMEX-1 dataset. Unlike other experiments in Europe, most of the ogives for the sensible and latent heat flux were found to
be convergent during NIMEX-1 in Ile-Ife. This can be attributed to the homogeneity of the surrounding bush, which lacks the
defined borders found in agriculturally cultivated landscapes. 相似文献
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Dr. Eckard Wallbrecher 《International Journal of Earth Sciences》1978,67(3):840-857
Zusammenfassung Es wird ein Cluster-Verfahren vorgestellt, mit dem in einer Menge von Richtungsdaten die Einzelwerte mit Hilfe eines vorgegebenen variablen Trennmaßes zu verschiedenen Gruppen zusammengefaßt werden. Richtungsstatistische Parameter werden für jede Gruppe berechnet. Außerdem wird ein Signifikanztest für die Trennung der Gruppen voneinander durchgeführt.
A cluster algorithm for orientation data is presented. It separates groupes of neighboring data by the use of a variable measure of separation. Statistical orientation parameters are calculated for each group and a significance test for the separation of the groups is carried out.
Résumé Un algorithme pour l'analyse des groupes de vecteurs est présenté. Il sépare des groupes de données voisines en utilisant une mesure variable de séparation. Des paramètres statistiques d'orientation sont calculés pour chacun d'eux, et un test de signification pour séparation des groupes est effectué.
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Martina Flörke Ellen Kynast Ilona Bärlund Stephanie Eisner Florian Wimmer Joseph Alcamo 《Global Environmental Change》2013,23(1):144-156
To enhance global water use assessment, the WaterGAP3 model was improved for back-calculating domestic, manufacturing and thermoelectric water uses until 1950 for 177 countries. Model simulations were carried-out on a national scale to estimate water withdrawals and consumption as well as cooling water required for industrial processes and electricity production. Additionally, the amount of treated and untreated wastewater as generated by the domestic and manufacturing sectors was modeled. In the view of data availability, model simulations are based on key socio-economic driving forces and thermal electricity production. Technological change rates were derived from statistical records in order to consider developments in water use efficiency, which turned out to have a crucial role in water use dynamics. Simulated domestic and industrial water uses increased from ca. 300 km3 in 1950 to 1345 km3 in 2010, 12% of which were consumed and 88% of which were discharged back into freshwater bodies. The amount of domestic and manufacturing wastewater increased considerably over the last decade, but only half of it was untreated. The downscaling of the untreated wastewater volume to river basin scale indicates a matter of concern in East and Southeast Asia, Northern Africa, and Eastern and Southern Europe. In order to reach the Millennium Development Goals, securing water supply and the reduction of untreated wastewater discharges should be amongst the priority actions to be undertaken. Population growth and increased prosperity have led to increasing water demands. However, societal and political transformation processes as well as policy regulations resulting in new water-saving technologies and improvements counteract this development by slowing down and even reducing global domestic and industrial water uses. 相似文献
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Dr. Paul F. Hamblin Dr. Eckard Hollan 《Aquatic Sciences - Research Across Boundaries》1978,40(1):119-154
Although the surface seiches of Lake Constance have been observed as early as 1549 and received serious scientific attention since 1893 in the classical work of Forel, they have only recently been investigated by modern hydrodynamical methods. It is the goal of this report to critically compare theoretical predictions of the periods and form of seiches with recent and historical observations as well as to examine the mechanisms of generation of these surface oscillations by means of applying measured atmospheric forcing in Lake Constance to a theoretical model. In the first part of this work, we review the findings of a large number of previous investigations, while the second part consists of a verification analysis of the model predictions of seiches. In the final part, we present a theory, predictions and observations of the excitation of seiches by arbitrary wind and barometric pressure gradient forcing. 相似文献
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Eckard Hollan 《Ocean Dynamics》1966,19(5):193-218
Zusammenfassung Für ein Beobachtungsbeispiel (Stromgeschwindigkeit, Dichte) aus der Kieler Bucht wird eine Deutung ausgeprägter Maxima der zugehörigen Spektren zwischen 0,3 und 60 Minuten durch interne Wellen gegeben. Mit einer beobachteten Periode von zwei Minuten durchgeführte Rechnungen ergeben eine starke Abhängigkeit der Wellenlänge von der mittleren Strömung
. Im Falle
erhält man bei 23,5 m Wassertiefe eine Wellenlänge von etwa 70 m, im Falle
von etwa 85 m. Die berechneten Schwingungen stellen uneigentliche interne Wellen dar (W. Krauß [1966]). Die Interpretation durch eine Grenzflächenwelle führt auf eine Wellenlänge von 86 m, die nur geringfügig von denen der internen Wellen 1. Ordnung in stetig sich ändernder Strömung
abweicht.In einer theoretischen Untersuchung werden kleinräumige Anfangsstörungen (z. B. momentane Druckänderungen an der Meeresoberfläche) als mögliche Ursache für die Entstehung kurzperiodischer interner Wellen erkannt. Es zeigt sich, daß kurzzeitig wirksame Anfangsbeschleunigungen in ihrem Einwirkungsbereich stehende, allmählich abklingende interne Wellen erzeugen, während in der Umgebung gleichzeitig fortschreitende Wellen entstehen, deren Amplituden mit wachsender Entfernung vom Erregungsgebiet abnehmen. Die Perioden der Schwingungen haben größere Werte als die zu einer exponentiellen Schichtung gehörige Väisäläperiode und verändern sich in Abhängigkeit von der Größe des Anregungsgebietes wie die zellularer Stabilitätsschwingungen.
The powerspectrum of internal motions in the western baltic between the periods 0.3 and 60 minutes. Part 1: Interpretation of the wavelike component of the internal unrest in the sea
Summary The powerspectra of the internal unrest in the sea show marked peaks in the range of periods between 0.3 and 60 minutes. An interpretation of these phenomena is given in terms of internal waves for a specific example obtained from short periodic current and density variations in the Kieler Bucht. The numerical calculations for an observed period of two minutes show an important influence of the vertical distribution of the current on the wavelength. In the case of the wavelength amounts to about 70 m, where as in the case of the length is about 85 m, assuming a depth of the sea of 23.5 m. The computed oscillations represent improper internal waves (W. Krauß [1966]). Interpretation by internal boundary waves yields a wavelength of 86 m, which is slightly different only from those of the first mode of internal waves in the case of continuously varying .By a theoretical investigation it is shown that short periodic internal waves may be caused by local initial perturbations (for instance by sudden variations of pressure at the surface). The solution of the problem describes slowly decreasing standing internal waves, which are generated within the area upon which short-dated initial accelerations have acted. At the same time a train of progressive waves is developed in the environment travelling away from the centre of the excitation. The amplitudes of these waves diminish with increasing distance from the origin. The periods of the computed oscillations yield higher values than the Väisäläperiod belonging to an exponential stratification. The variability in these periods is caused by variations in depth, by variations in stability, and by changes in the horizontal dimensions of the area of initial perturbation. This dependence is similar to that of cellular oscillations of stability.
Spectre des oscillations internes de la mer Baltique Ouest pour des périodes comprises entre 0,3 et 60 minutes. 1ère Partie: Interprétation des éléments ondulatoires de mouvement
Résumé Pour un cas d'observation (vitesse de courant, densité) en baie de Kiel, des maximums bien marqués des spectres correspondants entre 0,3 et 60 minutes s'expliquent par des ondes internes. Des calculs effectués avec une période de deux minutes montrent que la longueur d'onde dépend beaucoup du courant moyen, . Pour , par 23,5 m de profondeur, on obtient une longueur d'onde environ 70 m; pour , une longueur d'environ 85 m. Les oscillations calculées représentent des ondes internes qui ne sont pas des ondes propres. L'interprétation par une onde de surface limite conduit à une longueur d'onde de 86 m très peu différente de celles des ondes internes du premier ordre dans un courant constamment variable.Une étude théorique montre que des perturbations initiales peu étendues (par exemple variations momentanées de la pression à la surface de la mer) peuvent être à l'origine d'ondes internes à courte période. Il apparaît que des accélérations initiales, agissant brièvement, font naître dans leur zone d'action des ondes internes stationnaires qui s'amortissent peu à peu, tandis qu'en même temps aux alentours se produisent des ondes progressives dont l'amplitude décroît à mesure qu'elles s'éloignent de la région où elles ont pris naissance. Les périodes des oscillations ont des valeurs plus grandes que celle de la période de Väisälä rapportée à une stratification exponentielle, et elles varient suivant la grandeur de la zone où elles ont pris naissance comme les oscillations de stabilité cellulaire.相似文献
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This study presents the 26 major surface water types established in Austria in accordance with the draft of the EU Water Framework Directive (WFD). These types are made up of so‐called aquatic landscape units and large rivers. The 17 aquatic landscape units were defined using a database in which all Austrian running waters with a catchment area greater than 10 km[2] were described according to the following typological features: size of catchment area, altitude of catchment area and confluences, stream order, geology, zoogeographical regions (ecoregions), and subregions. At running waters with gauges, a classification according to flow regimes was carried out. Large rivers were defined as running waters with a stream order ⩾7 and/or a catchment area > 2500 km2 and/or with an average flow >50 m3/s. These major types represent, inter alia, the basis for the establishment of a surveillance monitoring network as required by the WFD. 相似文献
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