Wave loading on axisymmetric bodies using axisymmetric hybrid integral equation method     

M. M. F. Yuen 《Ocean Engineering》1987,14(1)

The wave diffraction problem on axisymmetric structures are solved by treating the fluid field as two separate domains. The velocity potential in the inner domain is represented by a 1/r type Green's function whilst that of the outer domain is represented by an eigenfunction expansion. The simple form of the Green's function in the inner domain reduces significantly the computational effort whilst the eigenfunction expansion in the outer domain is able to satisfy the radiation boundary condition completely. The method requires to have elements cover the entire containing boundary. Results for a number of typical structural geometries are presented and discussions are made on the effect of various parameters.  相似文献   

Geochemistry and palaeo-oceanography of metalliferous and pelagic sediments from the Late Cretaceous Oman ophiolite     

A. H. F. Robertson 《Marine and Petroleum Geology》1986,3(4)

Metalliferous and pelagic sediments are exposed within and above the extrusive successions of the Upper Cretaceous Oman ophiolite which, on the basis of mostly geochemical evidence, is believed to have formed in an incipient marginal basin setting located above a NE-dipping subduction zone. The ophiolitic extrusives document various volcano-tectonic settings which include the axial zones of a spreading ridge, fault-controlled seamounts and off-axis volcanic edifices. Most of the Fe, Mn and trace metal-enriched sediments studied are interpreted as precipitates formed by oxidation of solutions derived from high-temperature sulphide-precipitating vents. The trace element content (e.g. REE and Sr) was largely scavenged from seawater. The sediments are similar to the dispersed metalliferous sediments on the flanks of modern spreading ridges, and the ‘basal’ sediments of DSDP wells and of other ophiolite complexes (e.g. Troodos, Cyprus).Distinctive mound structures located low in the lavas are attributed to percolation of sulphide-rich solutions into already deposited metalliferous oxide sediments. The resulting iron-silica rock was probably originally precipitated as ferruginous silicates.Major massive sulphides formed off-axis at the base of intermediate-basic edifices of volcanic arc affinities. Fe, Mn and trace metal enrichment in the sediment cover of a flat-topped seamount of axial lavas is interpreted as a dispersion halo around the largest massive sulphide orebody which is situated 5 km away (Lasail). Small massive sulphide bodies are common in the axial lavas particularly along major seafloor fault zones. The metalliferous sediments, locally precipitated near these vents, are ferromanganiferous, but trace metal-depleted.The metalliferous and pelagic sediment cover of the extrusive successions, generally, documents waning hydrothermal input after volcanism ended in the area.A model is discussed in which the ophiolite was created at a spreading axis above a subduction zone dipping away from the Arabian continental margin. With progressive subduction this crust approached the margin. Initially, calcareous sediment accumulated above the calcite compensation depth (CCD), but then non-calcareous radiolarites were deposited as the ophiolitic crust approached the continental margin where the CCD was higher and marginal upwelling possibly enhanced productivity. As the edge of the Arabian continental margin entered the trench, the over-riding ophiolite was regionally uplifted allowing short-lived chalk accumulation above the CCD. This was followed by volcaniclastic deposition related to the tectonic emplacement.  相似文献   

Determination of characteristics of atmospheric motions from satellite multiwave remote sensing data     

A. F. Nerushev  E. K. Kramchaninova  V. I. Solov’ev 《Izvestiya Atmospheric and Oceanic Physics》2007,43(4):442-450

A method of determination of atmospheric dynamic characteristics from the data of remote sensing from a geostationary satellite is described. The method is based on the use of inhomogeneities in the concentration field of a conservative additive as tracers and on the application of correlation-extreme algorithms. Unlike the common methods used abroad, this method is able to determine not only the vector field of wind velocity but also the coefficient of turbulent diffusion and vorticity. Results of computations of the fields of the horizontal component of wind velocity and the effective coefficient of horizontal mesoscale turbulent diffusion from the Meteosat-8 SEVIRI water-vapor channel data are presented. It is shown that the average values of the effective coefficient of mesoscale horizontal turbulent diffusion in the areas with a predominantly turbulized air-mass motion are 1.5 times greater than in the areas where a laminar motion dominates. Specific features of the calculated values of the upper-troposphere dynamic characteristics in different stages of the North Atlantic TC Helene (September 2006) are analyzed.  相似文献   

Effects of cold eddy on phytoplankton production and assemblages in Luzon strait bordering the South China Sea   总被引：6，自引：0，他引：6  

Yuh-Ling Lee Chen  Houng-Yung Chen  I. -I. Lin  Ming-An Lee  Jeng Chang 《Journal of Oceanography》2007,63(4):671-683

The biochemical effects of a cold-core eddy that was shed from the Kuroshio Current at the Luzon Strait bordering the South China Sea (SCS) were studied in late spring, a relatively unproductive season in the SCS. The extent of the eddy was determined by time-series images of SeaWiFS ocean color, AVHRR sea surface temperature, and TOPEX/Jason-1 sea surface height anomaly. Nutrient budgets, nitrate-based new production, primary production, and phytoplankton assemblages were compared between the eddy and its surrounding Kuroshio and SCS waters. The enhanced productivity in the eddy was comparable to wintertime productivity in the SCS basin, which is supported by upwelled subsurface nitrate under the prevailing Northeastern Monsoon. There were more Synechococcus, pico-eucaryotes, and diatoms, but less Trichodesmium in the surface water inside the eddy than outside. Prochlorococcus and Richelia intracellularis showed no spatial differences. Water column-integrated primary production (IPP) inside the eddy was 2–3 times that outside the eddy in the SCS (1.09 vs. 0.59 g C m⁻²d⁻¹), as was nitrate-based new production (INP) (0.67 vs. 0.25 g C m⁻²d⁻¹). INP in the eddy was 6 times that in the Kuroshio (0.12 g C m⁻²d⁻¹). IPP and INP in the eddy were higher than the maximum production values ever measured in the SCS basin. Surface chlorophyll a concentration (0.40 mg m⁻³) in the eddy equaled the maximum concentration registered for the SCS basin and was higher than the wintertime average (0.29 ± 0.04 mg m⁻³). INP was 3.5 times as great and IPP was doubled in the eddy compared to the wintertime SCS basin. As cold core eddies form intermittently all year round as the Kuroshio invades the SCS, their effects on phytoplankton productivity and assemblages are likely to have important influences on the biogeochemical cycle of the region.  相似文献   

Eastern English Channel fish assemblages: measuring the structuring effect of habitats on distinct sub-communities   总被引：1，自引：0，他引：1  

Vaz  S.; Carpentier  A.; Coppin  F. 《ICES Journal of Marine Science》2007,64(2):271-287

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Surface heat fluxes and subsurface heat content at a site over the southeastern Bering Sea shelf, May–July 1996     

R. K. Reed  P. J. Stabeno 《Deep Sea Research Part II: Topical Studies in Oceanography》2002,49(26)

Observations from a surface mooring, in a weak-flow regime over the southeastern Bering Sea shelf, were used to derive surface heat fluxes for the period May–July 1996. Changes in heat content of the water column also were determined from subsurface temperature measurements. Agreement of net surface heat flux and change in heat content was within 2%. This result provides additional evidence that heat advection and diffusion are small in this region.  相似文献   

Spatio-temporal analysis of commercial trawler data using General Additive models: patterns of Loliginid squid abundance in the north-east Atlantic   总被引：5，自引：1，他引：5  

Denis  V.; Lejeune  J.; Robin  J. P. 《ICES Journal of Marine Science》2002,59(3):633-648

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The dynamic method of calculating currents and analysis of the vertical kinematic structure     

N. P. Bulgakov  S. N. Bulgakov 《Physical Oceanography》1996,7(6):427-435

The basic relations of the classical dyamic method have been complemented with the condition allowing for the non-monotonicity of the vertical kinematic structure. The elements of the multi-layered system of geostrophic currents have been found to correlate over depth with seawater density and hydrostatic pressure distribution. An example of the analysis of the vertical structure of currents, involving specific hydrological data, is given. Translated by Vladimir A. Puchkin.  相似文献   

The petroleum evaluation of a tectonically complex area: The western margin of the Southeast Basin (France)     

A. Mascle  R. Vially  E. Deville  B. Biju-Duval  J.P. Roy 《Marine and Petroleum Geology》1996,13(8):941-961

The Southeast Basin of France is the thickest onshore French sedimentary basin which contains locally as much as 10 km of Mesozoic-Cenozoic sediment. Basin development occurred in several stages between late Carboniferous and late Cretaceous times. Partial tectonic inversion took place during two compressive events, the so-called ‘Pyrenean’ and ‘Alpine’ phases of late Cretaceous-early Tertiary and late Tertiary ages respectively. They are separated by an intervening stretching event of Oligocene age, which further south resulted in the opening of the western Mediterranean oceanic basin. As a result of this complex tectonic history, structural traps were difficult to image on the seismic data shot during the first phase of exploration prior to 1980. Oil and gas natural seeps, and shows in several wells, indicate that some petroleum systems are, or have been active, at least in some places.The present erosional western margin of the basin is more or less superimposed on the initial Triassic-Jurassic margin. Margin subsidence and Tertiary inversion are discussed using regional sections on which the polyphase history of the entire basin is well shown. These sections are located on three major segments where the Mesozoic margin is either partly preserved (Ardèche), or has been partly inverted in late Tertiary times (Vercors-Chartreuse), or has been completely inverted in early Tertiary times (Corbières-eastern Pyrenees). 1-D ‘Genex’ basin modelling on the Ardèche segment, and 2-D ‘Thrustpack’ structural-maturity modelling in the Vercors-Chartreuse segment are used to further assess the remaining petroleum plays.  相似文献   

Relationships between temperature, population density, and growth in a seatrout population (S. trutta L.) of the Kerguelen Islands     

Davaine  P.; Beall  E. 《ICES Journal of Marine Science》1992,49(4):445-451

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