共查询到20条相似文献，搜索用时 46 毫秒
1.
E. G. Gus’kova O. M. Raspopov V. A. Dergachev A. G. Iosifidi G. V. Sinitsyna 《Izvestiya Atmospheric and Oceanic Physics》2012,48(8):823-831
Palaeomagnetic investigations of deposits at the Baranova Gora archaeological site located near Volgo Lake (56.9°N, 33.2°E) in the Central Russian Upland have been carried out. The palaeomagnetic studies have revealed the development of the Gothenburg geomagnetic excursion dated at 13000–12350 BP. Revealing the Gothenburg excursion allowed us to use the findings of the palaeomagnetic investigations as a chronological benchmark, in addition to the results of palynological and archaeological (comparative analysis of archaeological artifacts) methods of dating the cultural layers of this archaeological monument, as well as to refine the time frame of the climatic Allerød interstadial in the Central Russian Upland. The data obtained in our study indicate that the Allerød interstadial in the Central Russian Upland began several hundred years before 12000 BP, the date commonly believed to be the beginning of the Allerød interstadial. 相似文献
2.
High-resolution Echo-sounding and Detection of Embedded Archaeological Objects with Nonlinear Sub-bottom Profilers 总被引：3，自引：0，他引：3
Sub-bottom profilers based on nonlinear acoustics offer many advantages especially for detecting and locating embedded objects
in shallow waters. They have a narrow beam in spite of small transducers and virtually no side lobes. It is possible to realize
mobile low-frequent sub-bottom profilers, which transmit very short sound pulses. Excellent vertical as well as horizontal
resolutions at reasonable penetrations are proven benefits of using this technique. In this paper some technical aspects are
discussed and a new experimental nonlinear scanning sub-bottom profiler system is described. Results from a field trial in
archaeological prospection are shown to illustrate the successful application in practice. 相似文献
3.
Reflection Coefficient Calculation from Marine High Resolution Seismic Reflection (Chirp) Data and Application to an Archaeological Case Study 总被引：2，自引：0，他引：2
Chirp sub-bottom profilers produce high-resolution images of the near-surface. An attribute of the sea-bed reflection in chirp data are fluctuations in polarity between adjacent traces. Two models are proposed and presented to explain this: the first incorporates changes in an acoustic impedance gradient at the sea bed; the second uses changes in the thickness of the uppermost sediment layer. Mixing of adjacent traces produces a consistent polarity for the sea-bed reflector. Reflection coefficients are calculated, using amplitude information derived from single-traces, and polarity information from trace mixing, with application to a marine archaeological case study. The reflection coefficient calculated for the top of a buried 18th century wooden wreck is -0.26. 相似文献
4.
Marcello A. Mannino Kenneth D. Thomas Melanie J. Leng Hilary J. Sloane 《Geo-Marine Letters》2008,28(5-6):309-325
Shells of the rocky shore intertidal gastropod Osilinus turbinatus (von Born), often abundant in archaeological deposits in the Mediterranean region, are a potential source of data on palaeotemperature, palaeoseasonality and archaeological seasonality. To evaluate this species as a climate archive, investigations of annual patterns of shell growth and of monthly variations in oxygen isotopes in shell carbonates were made on different populations in NW Sicily. Mark-recapture experiments at San Vito lo Capo and Mazzaforno show that O. turbinatus grows almost continuously throughout the year but at different rates in different seasons. Around 75% of the yearly shell growth occurs in the autumn and winter. On average, larger/older shells produce narrower annual growth increments than smaller/younger ones. Conspicuous growth lines in larger/older shells show that growth stops during the hottest part of the summer. Oxygen isotope analyses on monthly collected shells of O. turbinatus from three shores (Cala Grande, Monte Cofano and Mazzaforno) show that the isotope values record temperature variations through the year. In all the datasets, surface seawater temperatures (SSTs) calculated from δ18OSHELL mostly underestimate measured SSTs, offsets being generally greater in summer. Minimum annual offsets range from 0.0°C to 0.7°C and maximum annual offsets from 3.1°C to 8.7°C. δ18OSHELL values fail to record temperatures higher than 25°C. Careful selection of shells to be analysed can reduce offsets between δ18OSHELL temperature estimates and measured SSTs for many parts of the year, except the hottest. Allowing for this, shells of O. turbinatus offer good potential as climate archives and for archaeological studies of seasonal patterns of human foraging for shellfish. 相似文献
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6.
《Journal of Sea Research》2004,51(3-4):313-328
Fishing effort has strongly increased in the North Sea since the mid-19th century, causing a substantial reduction in the population size of exploited fish stocks. As fisheries research has developed simultaneously with the industrialisation of the fisheries, our knowledge of population dynamics at low levels of exploitations is limited. Otoliths retrieved from archaeological excavations offer a unique opportunity to study growth rates in the past. This study compares historical and present-day growth rates for four commercially important demersal fish species. A total of 2532 modern otoliths (AD 1984–1999) and 1286 historical otoliths (AD 1200–1925) obtained from archaeological excavations in Belgium and Scotland were analysed. Comparison of the growth patterns between eras revealed a major increase in growth rate of haddock, whereas growth changes were not observed in saithe and only in the smaller size classes of plaice and cod. Comparison of our results with literature data indicates that the observed growth rate changes in plaice and cod occurred within the 20th century. Apparently the onset of industrialised fisheries has not greatly affected the growth of plaice, cod and saithe populations in the North Sea. This result contradicts the expectation of density-dependent limitation of growth during the era of pre-industrialised fishing, but is in agreement with the concentration hypothesis of Beverton (Neth. J. Sea Res. 34 (1995) 1) stating that species which concentrate spatially into nursery grounds during their early life-history may ‘saturate’ the carrying capacity of the juvenile habitat even though the adult part of the population is not limited by the adult habitat. 相似文献
7.
The usefulness of conventional fisheries science for long-term fisheries management and policies in the resource-poor islands of the Pacific is very limited. Fishery managers can, however, make use of such alternative sources of information as archaeological and historical data to develop fishery management initiatives. Most Pacific Islands were settled by humans over the last three millennia, although human settlement in Western Melanesia dates from the late Pleistocene, a period of about 40 millennia. Archaeological studies over the past half-century contain information on the long-term subsistence exploitation of fish and invertebrates from nearshore coral reefs and lagoons. Molluscs appear to have been a very important food source for early human colonists in the Pacific Islands, but declines in abundance through harvest pressure and environmental changes forced a greater reliance on fin-fish capture and on agriculture. There is no firm evidence from the archaeological record to suggest that long-term subsistence exploitation of reef fish populations has had any serious negative effects on abundance or structure of reef fish communities. Sources for more recent historical information are also exemplified and briefly examined for their usefulness in assessing the impacts of commercial fishing. It is argued that fishery managers who adopt a data-less approach to fishery management could profitably use these sources of information to enrich their assessment of the impacts of various management scenarios. 相似文献
8.
长江口区全新世古环境变化及其对黑潮变动的响应 总被引：8，自引：0，他引：8
将长江口区古环境变化的历史资料与冲绳海槽黑潮演变的沉积记录进行直接对比，确定了全新世百、千年尺度的气候波动和短期事件与长江口区生存环境变化的时间序列，发现人类社会的历史进程与自然的发展（气候波动）具有一定的对应关系，如黑潮增强、气候温暖时期适宜农业发展和社会稳定，而黑潮减弱、气候变冷时期容易发生人类迁徒和社会动荡。这不仅对于揭示全球气候演变机制，特别是短期气候事件至关重要，而且对于了解人类生存环境的变化趋势也具有相当重要的意义。 相似文献
9.
Leopoldo Franco 《Ocean & Coastal Management》1996,30(2-3)
Management and protection in coastal areas mainly addresses the natural environment and rarely addresses cultural and technical resources. This paper represents a plea for diverting more attention to some valuable historical features which exist, abandoned, along the Mediterranean shores.Along these shores a UN inventory identified some 1255 submerged archaeological coastal sites, many of which showed no signs of any protection from the attack of the sea and of growing coastal tourism. Many of them are remnants of harbour structures which are over 2000 years old.A condensed overview is given of the historical evolution of ancient harbour engineering, particularly related to the Roman age, describing the most interesting and innovative technological aspects, which could still add a valuable insight to the design of modern coastal structures. This knowledge was initially derived from literary and pictorial evidence and is now greatly expanded by the recent discoveries of underwater archaeology and by the developments of remote sensing technology.Co-operation between coastal engineers and archaeologists is encouraged, both for the preliminary surveys before the execution of new coastal works and for the interpretation, defence and revaluation of discovered maritime remains.Finally, recommendations for the restoration and creation of major ancient port sites as museums, possibly within innovative ‘coastal submarine archaeological parks’, are given. 相似文献
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11.
Coastal upwelling is a phenomenon of great importance both for the study of ocean dynamics and for the development of fish production in some coastal regions. Our study region, the Galician coast, lies at the northern end of the Canary–Iberian Peninsula upwelling system. Knowing the changes provoked by climate change on this upwelling system is particularly relevant for the future of this area taking into account the social and economic importance of fishing activities in this region. In this paper we study the trends in the intensity and frequency of upwelling in the Galician coast and the expected changes in this phenomenon for the next decades using three regional models implemented within the European project ENSEMBLES. As a main result, we observe that the models show a positive trend in both the intensity and frequency of upwelling phenomenon for the future, particularly significant in spring and summer which are the seasons favorable for upwelling. In autumn and winter there are no significant changes. 相似文献
12.
Marine archaeology is a new discipline which seeks to increase knowledge of man's past activities on the sea, through the study of the remains of his ships and other relics on the ocean floor. The author argues that marine archaeology, through its combination of techniques taken from marine ecology, geology, sedimentology and other sciences, has evolved to the point in the UK where it may be classified as a science in its own right. He discusses legal and social problems of the field, and points out the need for a ‘systems approach’ in marine archaeological projects. 相似文献
13.
Chirp sonar systems can be used to obtain high resolution seismic reflection images of the sub-seafloor during marine surveys. The exact knowledge of the Chirp signature allows the use of deterministic algorithms to process the data, similarly to that applied to Vibroseis data on land. Here, it is described an innovative processing sequence to be applied to uncorrelated Chirp data, which can improve vertical and lateral resolution compared to conventional methods. It includes application of a Wiener filter to transform a frequency-modulated sweep into a minimum-phase pulse sequence. In this way, the data become causal and can undergo predictive deconvolution to reduce ringing and enhance vertical resolution. Afterwards, FX-deconvolution and Stolt migration can be applied to obtain an improved imaging of the subsurface. The result of this procedure is a seismic reflection image with higher resolution than traditional ones, which are normally represented using the envelope function of the signal. This technique can be particularly useful for engineering-geotechnical surveys and archaeological investigations that require a fine detail imaging of the uppermost meters of the sub-seafloor. 相似文献
14.
A new global alignment approach for underwater optical mapping 总被引：1，自引：0，他引：1
Lately, underwater vehicles have become important tools for exploration, monitoring and creation of maps of the seabed. Within mapping applications, the maps obtained from optical data are becoming essential in different study areas such as biological, geological and archaeological surveys, or in detection of benthic temporal changes. However, the underwater medium is very challenging for optical sensors and does not allow the area of interest to be imaged in a single image. Therefore, image mosaicing methods are necessary. Although recent advances in detection of correspondences between images have resulted in highly effective image registration methods, global alignment methods are still needed to obtain a globally coherent mosaic. In this paper, we propose a new global alignment method which works on the mosaic frame and does not require non-linear optimisation. Additionally, a simple image rectifying method is presented to reduce the down-scaling effect which might occur when minimising errors defined in the mosaic frame. Moreover, this rectifying method can also be seen as an alternative and straightforward way of incorporating different sensor information if available. The proposed framework has been tested with underwater image sequences. The resulting method is faster than its counterparts while providing the same level of registration quality. 相似文献
15.
An unstable rock-slope is detected in Åkerneset, located in Storfjorden, Western Norway. In the future this rock-slope will produce a slide and a subsequent tsunami. In accordance to this future event, experiments in a 1:500 scale model of the inner part of Storfjorden are performed, where the model geometry is made after the real fjord bathymetry, while the slide is an idealized slide of block-type. The slide motion is monitored and the generated waves are measured at a number of wave gauges in the model. At selected locations local details of the flow, velocities and inundation are measured by digital image techniques and acoustic probes. Features of the wave system and the inundation are elaborately discussed with a view to the future event as well as to the application of models. 相似文献
16.
This paper analyses the trends and the future projections of significant wave height in several ocean areas at different parts of the world. It uses a stochastic Bayesian hierarchical space-time model, with a regression component with atmospheric levels of CO2 as covariates in order to estimate the expected long-term trends and make future projections towards the year 2100. The model was initially developed for an area in the North Atlantic ocean, and has been found to perform reasonably well there, and it is now investigated how the model performs for other ocean areas. 11 new ocean areas have been analysed with the model, and this paper presents the results pertaining to the estimated long-term trends and future projections of monthly maximum significant wave height for each of the 12 ocean areas. 相似文献
17.
太湖的形成和演变过程 总被引：21，自引：0，他引：21
洪雪晴 《海洋地质与第四纪地质》1991,(4)
本文从沉积学、地层学、地貌学、考古学和历史地理学角度,综合分析了太湖的成因和演变。认为地壳沉降与海面上升是构成江南碟形洼地的内外动力,为太湖的形成奠定了基础。全新世海侵最盛时,太湖海湾水深潮急、泻湖、滨海沼泽围绕海湾分布。随南部湾口沙嘴封堵,海湾趋于消失,陆地扩大,遗址增多。3700a来,海面回升,湖面逐渐扩展,形成现代太湖。 相似文献
18.
Roelof D. Schuiling Viorel Badescu Richard B. Cathcart Piet. A. L. C. Van Overveld 《Marine Georesources & Geotechnology》2005,23(1):25-37
Ocean gulfs offer a means of artificially creating a depression, which can be used for a regionally significant hydroelectric macroproject. We examine here the case for a dam at the Strait of Hormuz that blocks a large gulf situated in an arid region. A 35 m evaporation of this concentration basin will reduce its watery surface area by ∼53% and allow generation of ∼2.050 MW (or possibly ∼2.500 MW) of electricity. Our conclusion is that the proposed Electricity Development Infrastructure Node (EDIN) is a feasible and desirable macroproject. If the macroproject starts in the near-term future, it would require a significant change in the logistics of oil and gas transport from this region. Alternatively, it can be considered as an attractive future solution for the energy requirements of the region after exhaustion of its oil and gas reserves. 相似文献
19.
《Marine Policy》2016
Sweden and other European Union countries are currently carrying out extensive work aimed at improving the marine and freshwater environment. The adaptive management approaches typically used for this require the development of new policy instruments and measures when needed, but also evaluations of instruments and measures already in use or under way. This paper reports on a study of the Swedish individual transferable quota system introduced in 2009 for the pelagic fishery. The new system was motivated mainly by economic arguments and, thus, the need to get incentives right. Despite this, the design of the Swedish system weakened the intended incentive effects in several ways, compared with the foreign systems that served as models. Moreover, the information needed for future evaluations was not collected, even though the need for future evaluations had been expressed explicitly and the data needs for this could be identified at the time that the system was introduced. 相似文献
20.
Roelof D. Schuiling Viorel Badescu Richard B. Cathcart Piet. A. L. C. Van Overveld 《Marine Georesources & Geotechnology》2013,31(1-2):25-37
ABSTRACT Ocean gulfs offer a means of artificially creating a depression, which can be used for a regionally significant hydroelectric macroproject. We examine here the case for a dam at the Strait of Hormuz that blocks a large gulf situated in an arid region. A 35 m evaporation of this concentration basin will reduce its watery surface area by ～53% and allow generation of ～2.050 MW (or possibly ～2.500 MW) of electricity. Our conclusion is that the proposed Electricity Development Infrastructure Node (EDIN) is a feasible and desirable macroproject. If the macroproject starts in the near-term future, it would require a significant change in the logistics of oil and gas transport from this region. Alternatively, it can be considered as an attractive future solution for the energy requirements of the region after exhaustion of its oil and gas reserves. 相似文献