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1.
Emil V. Stanev Jörg-Olaf Wolff Hans Burchard Karsten Bolding Götz Flöser 《Ocean Dynamics》2003,53(1):27-51
In this paper we use a combination of numerical modeling and data analysis to gain a better understanding of the major characteristics
of the circulation in the East Frisian Wadden Sea. In particular, we concentrate on the asymmetry of the tidal wave and its
modulation in the coastal area, which results in a complex pattern of responses to the sea-level forcing from the North Sea.
The numerical simulations are based on the 3-D primitive equation General Estuarine Transport Model (GETM) with a horizontal
resolution of 200 m and terrain-following vertical coordinates. The model is forced at its open boundaries with sea-level
data from an operational model for the German Bight (German Hydrographic Office). The validation data for our model simulations
include time series of tidal gauge data and surface currents measured at a pile in the back-barrier basin of the Island Langeoog,
as well as several ADCP transects in the Accumer Ee tidal inlet.
Circulation and turbulence characteristics are investigated for typical situations driven by spring and neap tides, and the
analysis is focused on dominating temporal and spatial patterns. By investigating the response of five back-barrier basins
with rather different morphologies to external forcing, an attempt is made to elucidate the dominating physical balances controlling
the circulation in the individual sub-basins. It is demonstrated that the friction at the seabed tends to slow down the tidal
signal in the shallow water. This leads to the establishment of flood dominance in the shallow sea north of the barrier islands.
South of the islands, where the water volume of the channels at low tide is smaller than the tidal prism, the asymmetry of
the tidal signal is shifted towards ebb dominance, a feature which is particularly pronounced at spring tide.
At the northern open boundary, the tidal wave propagating from west to east generates a sea-level difference of ∼1 m along
the boundary, and thereby triggers vigorous alongshore currents. The frictional control in the model is located in the inlets,
as well as along the northern boundary. The correlation between velocity and turbulent kinetic energy tends to the establishment
of a net southward transport, giving theoretical support to the observed accumulation of sediments on the intertidal flats.
Weak turbulence along the northern shores of the barrier islands and the small magnitude of the residual currents there promote
accumulation of suspended matter in these areas, although wave action will generally counteract this effect.
Received: 29 May 2002 / Accepted: 26 September 2002
Responsible Editor: Jean-Marie Beckers
Acknowledgements We are indebted to S. Dick for providing the data from the operational model of BSH and to B. Flemming for the useful discussions.
The topography data and Fig. 1 have been prepared in cooperation with F. Meyer. Figure 2 has been prepared by G. Brink-Spalink.
We also thank for the comments from an anonymous reviewer which helped to improve our paper. 相似文献
2.
Qinglong You Shichang Kang Wolfgang-Albert Flügel Arturo Sanchez-Lorenzo Yuping Yan Jie Huang Javier Martin-Vide 《Theoretical and Applied Climatology》2010,101(3-4):445-457
The Tibetan Plateau (TP) with an average elevation of over 4,000 m asl is the highest and most extensive highland in the world. We used monthly mean sunshine duration from the Chinese Meteorological Administration to examine the spatial and temporal variability of sunshine duration at 71 stations with elevations above 2,000 m asl in the eastern and central TP during the 1961–2005 period. The temporal evolution of the mean annual sunshine duration series shows a significant increase from 1961 to 1982 at a rate of 49.8 h/decade, followed by a decrease from 1983 to 2005 at a rate of ?65.1 h/decade, with an overall significant decrease at a rate of ?20.6 h/decade during the whole 1961–2005 period, which is mainly due to the summer and spring seasons. This confirms the evidence that sunshine duration in the TP ranges from brightening to dimming in accordance with sunshine duration trends in the rest of China. The surface solar radiation downwards from ERA-40 reanalysis data in the same region confirms the brightening/dimming phenomenon shown by the sunshine duration before/after the 1980s. Otherwise, additional climatic variables such as low cloud amount, total cloud amount, precipitation, relative humidity and water vapor pressure, in most cases, exhibit significant negative correlation with sunshine duration in the TP on an annual and seasonal basis before and after 1982, respectively. The trends of these variables suggest that changes in some of them might be related to the brightening and dimming detected with the use of sunshine duration measurements over the TP. We also hypothesize that the impact of anthropogenic aerosols upon the climatic variables analyzed cannot be rejected, especially in the significant increase in low cloud cover since approximately 1980. 相似文献
3.
In the northern Flinders Ranges, Neoproterozoic and Cambrian sedimentary rocks were deformed and variably metamorphosed during the ca 500 Ma Cambro‐Ordovician Delamerian Orogeny. Balanced and restored structural sections across the northern Flinders Ranges show shortening of about 10–20%. Despite the presence of suitable evaporitic detachment horizons at the basement‐cover interface, the structural style is best interpreted to be thick‐skinned involving basement with only a minor proportion of the overall shortening accommodated along stratigraphically controlled detachments. Much of the contractional deformation was localised by the inversion of former extensional faults such as the Norwest and Paralana Faults, which both controlled the deposition of Neoproterozoic cover successions. As such, both faults represent major, long‐lived structures which effectively define the present boundaries of the northern Flinders Ranges with the Gawler Craton to the west and the Curnamona Craton to the east. The most intense deformation, which resulted in exhumation of the basement along the Paralana Fault to form the Mt Painter and Babbage Inliers, coincides with extremely high heat flows related to extraordinarily high heat‐production rates in the basement rocks. High heat flow in the northern Flinders Ranges suggests that the structural style not only reflects the pre‐Delamerian basin architecture but is also a consequence of the reactivation of thermally perturbed, weakened basement. 相似文献
4.
Frank?BraunschweigEmail author Flávio?Martins Paulo?Chambel Ramiro?Neves 《Ocean Dynamics》2003,53(3):137-145
High-resolution hydrodynamic models are a common tool to simulate water dynamics in estuaries. Results from these models are, however, difficult to interpret without the aid of additional parameters to integrate the information. In this paper a methodology to understand the transport patterns in the Tagus Estuary is proposed. It is based on the computation of two renewal time scales: residence time and integrated water fraction. This last parameter is used to build a dependency matrix that gives the integrated influence of each region of the estuary at a selected point. The parameters are computed using a Lagrangian transport model coupled to the hydrodynamic model. Results show that Tagus Estuary has two different types of regions: the central part of the estuary, with low renewal efficiency, and three regions with higher renewal efficiency. Renewal mechanisms are, however, different for each region as shown by the dependency matrix. Comparison of renewal time scales with results from a water-quality model revealed that residence time is not a limiting parameter for primary production in the Tagus Estuary.Responsible Editor: Hans Burchard 相似文献
5.
The Periadriatic Lineament and its possible extension, the Balatonline, on the one hand and the Balcan-Dinaric Lineament and its continuation (?) the Zagreb-line, on the other hand, separate an outer-region, characterized by clastic, terrestrical Upper Carboniferous and Permian strata, from a marine Inner-region. This Inner-region includes the Southern Alps, the Dinarides, and the ?Igoler“-trough. The aforementioned lineaments were not evident during the Lower Paleozoic, whereas in the Upper Paleozoic (after the Variscan orogenese) a clear separation of the two areas can be seen. As a consequence of the overlapping of the marine sequence into the regions north of the Periadriatic lineaments during the Triassic, the contrast between outer- and inner-regions are agained wiped out. For a full understanding of these facts, significant details are still missing. Above all it is important to find a solution for several still unanswered questions: how far the outer region is still a part of the paleomagnetic “Stabile Europe”; how far the metamorphic development within the region of the Balcan Peninsula, the Pannonic Basin and the Karpates can be compared with the ideas (supported by isotopic-geological dates) of the metamorphic development on both sides of the Insubric line and also how far the Dinaric Ophiolite zones are remains of a Paleothetys. Only when these questions are answered will it be possible to insert the Variscan area into the discussion of plate-tectonics within the Neo-European region. 相似文献
6.
W. Flüchter Dr. 《GeoJournal》1980,4(3):247-257
Conclusions Central place preference by social geographic groups is in the Tokyo area less determined by social status than by age and life cycles differentiated by sex.In case of the tributary area of Shibuya a simple classification into young people (male and female bachelors) and married people (husbands and housewives) indicates essential differences in central place preferences between these groups.The bachelors, particularly the young men, are most important for central place orientations in that they show distinctive spatial behavioural patterns in terms of complexity, mobility and intensity of distance-movements. The young people being employed — today joculously called dokushin kizoku (bachelors' aristocracy) because of their salary raised remarkably as well as of their extensive concumer demands and high buying power — are representative for the present-day economically independent young generation. The bachelors judge urban center attractiveness on the basis of shopping facilities and also in terms of atmosphere — meeting friends, strolling through town and amusing themselves. The young people are very much courted by commercial enterprises and are regarded as special trend setters having great influence on the image and vitality of Tokyo's inner urban centers.Most attractive for the young people are the ring centers. In the southwestern suburban areas Shibuya predominates; however generally speaking it is Shinjuku, the western and leading (ring)-center, which draws the young people most strongly. Special centers such as Harajuku, Aoyama and Roppongi are also preferred by this group, often in combination with a ring-center visit. Towards the inner city core (Ginza-Nihonbashi) central place preferences chiefly of the young male bachelors are declining gradually.Compared with young people the married people prefer the ring centers only slightly before the Ginza area, which for shopping is primarily visited by housewives, for going out mainly by husbands. Particularly in the inner city core near the main office districts a typical feature for Tokyo of central place preference is evident. For the salaryman — the most representative business type in the Tokyo area — going out is identical with not going home. This phenomenon depends on the place of work in two aspects. First, spatially in terms of a close connection between office and inner city amusement/shopping centers and additionally distance-movements towards a ring center nearest of the place of work or residence. Second, socially — social activities after working hours mainly carried out with colleagues result in a behavioural pattern, in which a clear differentiation between company and private life appears to be difficult. For not going home there are many reasons — among others the constricted living conditions of Japanese homes as Westerners believe — however, other factors play a much more important role: (i) Mainly the extremely long commuting distances, which allow the salaryman a real leaving home to go out only on Sundays or holidays. Other reasons for this typically Japanese feature closely related to inner city tavern and bar visits, may be seen in (ii) the traditionally very limited participation of Japanese housewives to their husbands' out-door social activities; (iii) a system of charging and crediting expenses to one's personal bank account or the company account; (iv) the personal atmosphere of taverns and bars providing the best chances for communication/relaxation and for overcoming stress and frustrations experienced in the office.Shopping is particularly for housewives the most important motivation for visiting urban centers, in this respect two Japanese characteristics should be mentioned: First, fashion and being well-groomed are, as far as the mass of people particularly the young women is concerned, more highly esteemed than in other urban societies. As a consequence good clothes are much in demand. Purchases of these kinds of articles are most often made in department stores and cause the longest distance-movements. Second, in rank of central goods next to fashion and quality clothes follow standard gifts such as seibo and chugen. The purchase of these articles is apart from the unique custom of giving gifts twice a year typically Japanese also in so far as it contradicts the least-effort criterion in central place theory. Though these patterns mostly bought by housewives or middle-aged and older people are substantially more of daily or periodical than episodical demand, they are related to surprisingly long distance-movements because of usually being bought for image reasons in leading department stores located in higher-ranking more distant urban centers.Typical behaviour for all groups visiting higher-order urban centers is an often used combination of shopping and taking part in out-door activities such as meeting friends/acquaintances, strolling around, going to the cinema or other show performances, eating, drinking and chatting together. This is due to the outstanding facilities available not only in retail-trade but also in the gastronomic, entertainment and amusement sectors.Taken all together, complexity and intensity of central place preferences in Tokyo reflect the higher and different attractiveness of Japanese urban centers compared with that of other urban societies. The urban centers are highly esteemed because of their excellent facilities as well as of their vitality, crowds and activity. These latter characteristics are summarized by the word nigiyaka meaning vivacity, which is most typical for Japanese urban centers. The inner city centers of Tokyo can be regarded in the true sense of this term as urban foci compensating for diverse problems such as environmental pollution or lack of inner urban green areas, making life in the most densely populated area of the world worthwhile. 相似文献
7.
The structure of the microcrystalline silica varieties chalcedony, flint, moganite, opal-C and -CT is characterized by X-ray powder diffractometry and transmission electron microscopy (TEM). The role of impurities is investigated by infrared spectroscopy and chemical analysis. Microcrystalline opal, chalcedony and flint have a disordered intergrowth structure composed of cristobalite and tridymite domains in opal, and quartz and moganite domains in chalcedony and flint. Each constituent phase has different cell dimensions and symmetry. The main impurity is water which is enriched at the intergrowth interfaces. Density and refractive indices of microcrystalline silica depend on the water content. 相似文献
8.
The presence of matter in its different forms in a hexadimensional space-time, where gravitation is coupled to a conformal field, generates a class of cosmological solutions with very peculiar features: the initial proper distance between any two points of the space-time is infinite, following successive contraction and expansion phases in the evolution of the Universe. This behaviour defines a Anti-Big Bang Singular Cosmology. In this article we analyze this primordial cosmological scenario considering different matter forms and the effects of a Conformal Transformation on the metric. 相似文献
9.
Zusammenfassung Ein lange unbestimmtes, nadeliges Mineral aus der bekannteu, mineralreichen Kalksilikatparagenese von der Lieserschlucht (Lit. 4) wurde optisch und röntgenographisch alsPumpellyit (Lotrit) identifiziert. 相似文献
10.
Jacqueline Flückiger Reto Knutti James W. C. White Hans Renssen 《Climate Dynamics》2008,31(6):633-645
Greenland ice cores, as well as many other paleo-archives from the northern hemisphere, recorded a series of 25 warm interstadial
events, the so-called Dansgaard-Oeschger (D-O) events, during the last glacial period. We use the three-dimensional coupled
global ocean–atmosphere–sea ice model ECBILT-CLIO and force it with freshwater input into the North Atlantic to simulate abrupt
glacial climate events, which we use as analogues for D-O events. We focus our analysis on the Northern Hemisphere. The simulated
events show large differences in the regional and seasonal distribution of the temperature and precipitation changes. While
the temperature changes in high northern latitudes and in the North Atlantic region are dominated by winter changes, the largest
temperature increases in most other land regions are seen in spring. Smallest changes over land are found during the summer
months. Our model simulations also demonstrate that the temperature and precipitation change patterns for different intensifications
of the Atlantic meridional overturning circulation are not linear. The extent of the transitions varies, and local non-linearities
influence the amplitude of the annual mean response as well as the response in different seasons. Implications for the interpretation
of paleo-records are discussed. 相似文献