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 共查询到20条相似文献，搜索用时 15 毫秒
1.
Studies on coastal physical oceanography
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2.
A study of upwelling on the basis of meteorological and oceanographical data (in Japnese)
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3.
Zooplankton ecology with particular reference to the behaviour of diurnal vertical migration
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4.
Submarine geology of trenches in the Northwest Pacific
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5.
Ecological studies on the primary productivity in the ocean
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6.
A wrong finite difference form is used for the rotation of the Coriolis force in the vorticity equation with bottom topography in a series of papers byEndoh.  相似文献   

7.
The advection term in the finite difference diffusion equation can give rise to the false computational oscillation unless the ratio of the grid size to the coefficient of eddy diffusivity is smaller than a critical value. The slightly uncentered differencing scheme is useful for the advection term.  相似文献   

8.
Résumé Une série de profils de sismique réflexion effectués au large de la Tunisie et dans le détroit sardano-tunisien aboutissent à l'élaboration d'un schéma géologique interprétatif dans lequel nous replaçons le socle paléozoïque et sa couverture autochtone (Eocène et plio-quaternaire) et allochtone (nappe numidienne). Nous discutons ensuite des manifestations néotectoniques (bassins d'effondrements plio-quaternaires-mouvement de flexure-surrections locales-venues intrusives). Enfin la nature du substratum du détroit sardano-tunisien est discutée en liaison avec les hypothèses dynamiques et statiques relatives à la formation de la Méditerranée occidentale.
Serial seismic reflection profiles off Tunisia and between Sardinia and Tunisia are presented. Interpretation is given which includes paleozoïc basement and its autochtonous (Eocene and plioquaternary) and allochtonous (Numidian nappe) cover. Recent tectonic activity is discussed, (Plioquaternary foundered basins, flexure, local uplifts, intrusions). Then the nature of the basement of the Sardinia-Tunisia zone is discussed with respect to the various hypotheses on the region of the Western Mediterranean.
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9.
By a model bay with a mouth and a narrow, an experiment on long period waves is carried out to discuss the behavior of the tsunamis and storm surges. Emphasis is placed on the analysis of the characteristics of the current velocities associated with the long period waves incoming through the mouth in terms of Ursell's parameter.  相似文献   

10.
When river water mixes with sea water in estuary area, the concentrations of the dissolved element in river water may be changed by either a simple physical mixing process or some complex chemical processes. It has been clarified in the Chikugogawa River estuary area that the change in concentrations of SO 4 2− , BO 3 3− , Mg2+, Ca2+ and F− is only due to the mixing process but the change in concentrations of SiO 3 2− and Al3+ is due to the chemical process in addition to the mixing process.   相似文献   

11.
Résumé L'étude de plusieurs profils de sismique réflexion, magnétisme et gravimétrie a permis de dégager les grands traits de la structure de la marge continentale à l'ouest du Spitzberg. Cette marge est représentée au niveau du talus continental par un bassin sédimentaire dont la largeur se réduit en allant vers le Nord. Ce bassin est limité à l'Ouest par les premiers contreforts de la dorsale d'Atka qui a joué un rôle de barrage pour les apports sédimentaires. Les données de la sismique réflexion et du magnétisme indiquent que la vallée d'Atka est sans doute une zone actuelle d'expansion. Ces résultats sont en bon accord avec le modèle récent d'ouverture de la mer de Norvège. De plus, la dorsale d'Atka semble avoir subi au pliocène un réajustement ayant modifié les processus sédimentaires au niveau de la marge.
The main structural features of the continental margin off West Spitzberg are outlined. Seaward the Atka ridge has acted like a dam for the eastward-flowing sediments and thus helped to build up a large sedimentary basin, narrowing towards the North. Magnetic and seismic data show that the Atka Valley is probably an active accretion rift valley. These results are in good agreement with the last hypothesis on the opening of the Norwegian Sea. During the Pliocene, a tectonic event may have affected Atka ridge and modified the subsequent sedimentation.

Contribution No. 258 du Department Scientifique du Centre Océanologique de Bretagne.  相似文献   

12.
It is pointed out that the rate of advance of a small transient meander east of Kyushu, which (according to the meager evidence available) seems to precede the formation of the large stable Kuroshio meander south of Kumano Nada and Enshu Nada, shows order of magnitude agreement with the barotropic Rossby wave velocity calculated on the assumption that the entire contiguous downstream flow (not merely the strong near-axis flow) behaves as a unified dynamical entity.  相似文献   

13.
《Ocean & Coastal Management》2003,46(6-7):649-679
In 1995, in response to the distressed condition of the British fishing industry, the House of Lords held a series of hearings on “Fish Stock Conservation and Management.” Lord Perry of Walton posed the straightforward question of why regulation was not succeeding:
If one takes all the management systems into account—TACs [total allowable catches, or annual quotas], number of days at sea and the decommissioning programme—none of them has stopped the gross over-fishing that has taken place. There seem to be three factors to account for it: first, the scientific advice that is given; secondly, how far that advice is accepted by politicians who set the TACs and quotas; and, thirdly, whether the fishermen obey the regulations. Which of these are the most at fault at the moment?
Lord Perry's question led us to ask to what degree publicly available information in the United States could shed light on the sources of overfishing in individual fisheries—what we will call “regulatory overfishing.” First, we set out a typology of the potential sources of regulatory overfishing. Next, we examine two case illustrations of federally managed, overfished fisheries in the United States. Each case generates important insights into the causes of regulatory overfishing and lessons for future management. In the final section of the paper, we make several suggestions aimed at improving fisheries management and the management process.  相似文献   

14.
A simple advection-diffusion model is applied to the deep water of the North Pacific Ocean. The physical mixing parameter, i.e., the ratio of vertical advection velocity (W) to vertical eddy diffusivity (D), is obtained from the vertical distribution of a conservative property such as salinity. The rate of decomposition of organic matter is estimated from the oxygen consumption rate which is obtained from dissolved oxygen content. The calcium carbonate flux in the deep water is obtained from alkalinity. Using these values and the vertical distribution of a radioisotope,14C or226Ra, the vertical eddy diffusivity and the upwelling velocity are found to be 1.2 cm2/sec and 1.4 ×10–5 cm/sec, respectively, at the Geosecs 1969 station. The oxygen consumption rate at 3 km depth of the station is found to be 1.4×10–3ml/l/yr.  相似文献   

15.
Resumé Cet article présente des données bathymétriques et magnétiques de la région axiale de la dorsale sud-ouest indienne au voisinage de la zone de fracture majeure Atlantis II. Elles proviennent pricipalement de la campagne MD34 (Marion-Dufresne, 1983).L'axe de la dorsale est défini par la vallée et l'anomalie magnétique qui lui est associée. Le rilief le long de l'axe varie localement très rapidement; A l'ouest de la zone de fracture Atlantis II, le plancher axial présente deux bombements séparés par une dépression importante (4600 m). Cette étude met en évidence la corrélation entre ces hauts bathymétriques, la forme de la vallée et la l'amplitude de l'anomalie magnétique axiale: lorsque la profondeur du plancher axial diminue, la vallée se creuse et son encaissement augmente. On observe ainsi sur les hauts bathymétriques une section d'axe très encaissée, associée à une anomalie magnétique d'amplitude plus importance.L'identification de l'anomalie 5 (10 Ma) sur chaque flanc de la dorsale sud-ouest indienne permet la reconstitution de cette isochrone qui montre clairement une évolution de la géométrie de l'axe: à l'époque de l'anomalie 5, l'axe était composé de segments perpendiculaires à la direction d'expansion, décalés par des failles transformantes, alors qu'il apparait actuellement continu et formé sur les hauts topographiques de courts segments perpendiculaires à la direction d'expansion (et dans les dépressions par des sections d'axe très obliques).La carte bathymétrique met en évidence des lignes de crêtes grossièrement Nord-Sud (007°) dont la direction diffère de la direction d'expansion (357°) déduite des reconstructions, et parallèle à la zone de fracture majeure Atlantis II. Sur les dorsales lentes, les zones de fractures mineures, n'indiqueraient donc pas la véritable direction d'expansion.
The axial region of the Southwest Indian Ridge between 53° E and 59° E: Evolution during the last 10 Ma
An interpretation of bathymetric and magnetic data obtained aboard the R/V Marion Dufresne provides us with new information concerning the evolution of the Southwest Indian Ridge, in the region of the Atlantis II Fracture Zone (57° E), since 10 Ma. On all profiles, the ridge axis and the axial magnetic anomaly have been clearly recognized. Bathymetric data illustrate the rapid variation of depth along the axis. On the western side of the Atlantis II Fracture Zone, the along axis profile is characterized by a succession of two highs, and an important depression between them.Our data show a strong relationship between the regional axial depth, the steep-sidedness of the axial valley and the signature of the central magnetic anomaly. In particular, where the axis is deepest (4500 m), there is a wide, shallow axial valley which is oblique to the spreading direction, and a non-typical central magnetic anomaly signature. In contrast, where the regional axial depth is shallow (3500 m), the axial valley is deep, narrow, perpendicular to the spreading direction, and the central magnetic anomaly is high in amplitude. The ridge axis on the western side of the Atlantis II Fracture Zone appears to consist of short segments located on the axial highs, which are linked by oblique zones. On the eastern side, the ridge axis is continuous, and appears to be oblique to the spreading direction.Clearly lineated magnetic anomalies 3A (5 Ma) and 5 (10 Ma) have been identified and mapped. These magnetic data allow a reconstruction which shows an evolution of the axial geometry since 10 Ma. On the western side of the Atlantis II Fracture Zone, the axis at anomaly 5 time consisted of segments perpendicular to the spreading direction which were offset by transform faults. On the eastern side, the isochron A5 appears to be parallel to the present-day ridge axis. From this plate reconstruction, a spreading direction of 357° was deduced, and appears to be parallel to the Atlantis II Fracture Zone.On each flank of the Suuthwest Indian Ridge, our bathymetric data show elongated ridges, aligned in a north-south direction, which correlate with the axial topographic highs. This direction is not precisely parallel to the spreading direction deduced from plate reconstruction. The differences in these directions suggest that transverse relief on show spreading ridge flanks (which could be interpreted as indicating the location of minor fracture zones) may not be indicative of the seafloor spreading direction.
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16.
This article summarizes the author's work on210Pb and210Po distributions in the marine environment for which the Okada Prize of the Oceanographical Society of Japan was awarded. In this review, the work of other investigators and the studies now going on are also included. The210Pb concentration in the surface water of the ocean is controlled by the atmospheric flux of210Pb and productivity. The disequilibrium between226Ra and210Pb in the deep sea reveals that the oceanic residence time of lead is less than a hundred years rather than of the order of thousands of years as thought before based on stable lead measurement in ocean water. Particulate removal of210Pb from the water column is likely to be the major cause of the deficiency of210Pb in the water, however more investigations would be needed to clarify the detailed removal mechanism of210Pb. The experiments on particulate flux by using sediment traps will provide an unique opportunity to examine this. 210Pb in excess of226Ra in sediment is useful for geochronology of shallow water sediments and the study on bioturbation rates on the deep sea sediments.  相似文献   

17.
The accumulation rates of sediment cores in Osaka Bay have been determined by using210Pb dating technique. In the upper 10 cm210Pbex contents show a constant value with depth. The accumulation rates below the homogeneous layer of sediments ranging from 0.12 to 0.61cm y–1 (0.067–0.34 g cm–2 y–1) were obtained. The higher contents of Zn, Cu, Pb and Cr were observed in the upper 10 to 30 cm of sediments. Assuming that the increment of heavy metal content in sediments is due to anthropogenic origin, the amount of anthropogenic input of heavy metals into sediments were estimated to be 1,300–2,700g cm–2 for Zn, 150 – 480 for Cu, 360 – 410 for Pb and 320 – 480 for Cr. The increment appears to start about 100 years ago. In surfical sediments most of heavy metal contents exceeded the background content, and then most part of Osaka Bay is polluted by heavy metals.  相似文献   

18.
From July to November, the thermocline which has strong temperature gradient (0.7C m–1) is formed in the bottom water of Beppu Bay, and it prevents the downward mixing of surface water. This has caused the bottom water of the basin to become depleted in oxygen, and in November the bottom water below about 60 m depth becomes anoxic. Accordingly manganese and iron are reduced and more soluble under the anoxic condition, those concentrations are high relative to surface water, and the maximums are 1,240g l–1 and 80g l–1. Under the anoxic condition, the flux of dissolved manganese from the sediment is about 10g cm–2 day–1.  相似文献   

19.
Macrobenthos were investigated at 77 stations on the level bottom of Maizuru Bay in the spring season in 1971. Among the animals collected in this survey, two animal groups,i.e. bivalves and polychaetes, predominated.Theora lubrica was the most predominant species, occupying 39 % of the total individuals collected. An apodan holothurian,Notomastus sp.,Prionospio ehlcrsi andLumbrineris longifolia also prevailed in number.According to the similarity of the composition of eight species common in the present area, the sampling stations were classified into four categories. As the stations belonging to each category are distributed in a peculiar portion of the bay, the bay can be divided into four areas, A–D, which are characterized as follows: Area A,Theora lubrica is highly predominant; Area B, an apodan holothurian and six common polychaetes (Notomastus sp.,Lumbrineris longifolia, Paraprionospio pinnata, Glycera chirori, Tharyx sp. andPolycirrus sp.) are relatively abundant; Area C, intermediate between Areas A and B; Area D, the above-mentioned eight species are scanty. These regional divisions of the bay correspond well with those based on the physico-chemical conditions on the bottom. Benthic feature of each area of the bay was discussed in connection with the bottom environment.Comparison of the present results with the previous data has revealed a considerable decrease of population density during the past 25 years in the area concerned.  相似文献   

20.
This is a review of the study on the oceanic environments relating to the marine living resources carried out since 1947, during more than 35 years which are the period of the authors oceanographic research life for fisheries. Its content consists of describing the outlines of, (1) the oceanographic study of the Subarctic Region of the Northwestern Pacific as the salmon living waters, (2) the study on dilution processes of the effluent in the coastal waters in relation to marine pollution, (3) the oceanographic study on transportation and diffusion of fish eggs and larvae in relation to the recruitment of living resources and (4) the study on forecasting of the fisheries and oceanographic conditions, and a short note on direction of fisheries oceanography expected to be studied in the future.  相似文献   

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