Importance of spawning location and timing to successful transport to nursery areas: a simulation study of Gulf of Alaska walleye pollock   总被引：2，自引：0，他引：2  

Hinckley  Sarah; Hermann  Albert J.; Mier  Kathy L.; Megrey  Bernard A. 《ICES Journal of Marine Science》2001,58(5):1042-1052

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Prolonged Magmatic and Tectonic Development of the Caribbean Igneous Province Revealed by a Diving Submersible Survey     

Mauffret  Alain  Leroy  Sylvie  Vila  Jean-Marie  Hallot  Erwan  Mercier de Lépinay  Bernard  Duncan  Robert A. 《Marine Geophysical Researches》2001,22(1):17-45

Using the diving submersible survey NAUTICA we investigated the central part of the Caribbean large igneous province (CLIP) to observe and sample internal portions of this proposed oceanic plateau. Most of the samples are gabbroic and doleritic rocks; basalts are scarce. Radiometric dating by ⁴⁰Ar/³⁹Ar incremental heating experiments indicate that the intrusive rocks are Campanian in age (81–75 Ma). In some places these intrusive rocks underlie older Santonian (85–83 Ma) extrusive basaltic rocks, suggesting that the Campanian rocks represent a sill injection and an underplating episode. Results of the diving program supplemented by information from ODP and DSDP drilling sites document a 20 m.y. period (94–75 Ma) of igneous activity in the submerged portion of the Caribbean large igneous province (CLIP). In the northern part of the Beata Ridge late Campanian and/or post Campanian uplift is documented by prominent Maastrichtian (71–65 Ma) erosion and the establishment of a Paleocene-middle Eocene (65–49 Ma) carbonate platform. During and after the uplift an extensional period is indicated by seismic images and the subsidence (3 km depth) of the carbonate platform. Paleocene ages (55–56 Ma) determined on some volcanic samples are attributed to localised decompression mantle melting that accompanied the extension. We document a prolonged period of magmatic and tectonic events that do not fit with the current models of short-lived plateau formation during mantle plume initiation but shares many similarities with the constructional histories of other oceanic large igneous provinces.  相似文献   

Distribution of population-based indicators across multiple taxa to assess the status of Gulf of Alaska and Bering Sea groundfish communities     

Mueter  Franz J.; Megrey  Bernard A. 《ICES Journal of Marine Science》2005,62(3):344-352

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On the use of current meter data to assess the realism of ocean model simulations     

Thierry Penduff  Bernard Barnier  Jean-Marc Molines  Gurvan Madec 《Ocean Modelling》2006,11(3-4):399-416

The evaluation of ocean simulations against observed datasets is essential to assess their realism and to guide model development, but often remains qualitative, and ignores certain datasets. This paper presents a three-dimensional, quantitative comparison of a 1/6° Atlantic numerical simulation (CLIPPER) with the WOCE current meter dataset in terms of mean velocity and eddy kinetic energy. Our metrics reveal the good behaviour of CLIPPER open boundary conditions and forcing with respect to full-depth current records. Due to its still moderate resolution, however, the model globally underestimates the observed mean speeds and eddy activity. This discrepancy is barely noticeable at low latitudes but increases toward the poles, probably since the poleward decrease of the Rossby radius exceeds that of the horizontal grid step. At least in this eddy-admitting regime, it is suggested that the numerics of geopotential-coordinate models like ours dissipate mean and eddy momentum at depth and adversely affect current–topography interactions.  相似文献   

High-resolution measurements of chromophoric dissolved organic matter in the Mississippi and Atchafalaya River plume regions   总被引：4，自引：0，他引：4  

Robert F. Chen  G. Bernard Gardner 《Marine Chemistry》2004,89(1-4):103

Chromophoric dissolved organic matter (CDOM) was measured in the spring and summer in the northern Gulf of Mexico with the ECOShuttle, a towed, instrumented, undulating vehicle. A submersible pump mounted on the vehicle supplied continuously flowing, uncontaminated seawater to online instruments in the shipboard laboratory and allowed discrete samples to be taken for further analysis. CDOM in the northern Gulf of Mexico was dominated by freshwater inputs from the Mississippi River through the Birdfoot region and to the west by discharge from the Atchafalaya River. CDOM was more extensively dispersed in the high-flow period in the spring but in both time periods was limited by stratification to the upper 12 m or so. Thin, subsurface CDOM maxima were observed below the plume during the highly stratified summer period but were absent in the spring. However, there was evidence of significant in situ biological production of CDOM in both seasons.The Mississippi River freshwater end member was similar in spring and summer, while the Atchafalaya end member was significantly higher in the spring. In both time periods, the Atchafalaya was significantly higher in CDOM and dissolved organic carbon (DOC) than the Mississippi presumably due to local production and exchange within the coastal wetlands along the lower Atchafalaya which are absent along the lower Mississippi. Nearshore waters may also have higher CDOM due to outwelling from coastal wetlands. High-resolution measurements allow the differentiation of various water masses and are indicative of rapidly varying (days to weeks) source waters. Highly dynamic but conservative mixing between various freshwater and marine end members apparently dominates CDOM distributions in the area with significant in situ biological inputs (bacterial degradation of phytoplankton detritus), evidence of flocculation, and minor photobleaching effects also observed. It is clear that high-resolution measurements and adaptive sampling strategies allow a more detailed examination of the processes that control CDOM distributions in river-dominated systems.  相似文献   

La Distribution Du Nitrite Dans Le Systeme Des Courants Equatoriaux De L'OCean Pacifique, A 170{degrees}E     

Hisard  Philippe; Piton  Bernard 《ICES Journal of Marine Science》1969,32(3):303-317

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Geochemistry of suspended matter from the Baltic Sea 2. Results of bulk trace metal analysis by AAS     

Lutz Brügmann  Paul C. Bernard  Rene van Grieken 《Marine Chemistry》1992,38(3-4)

In 1984, on a transect covering the whole Baltic Sea and parts of the adjacent North Sea, 160 water samples were taken and analysed for their concentrations of particulate and dissolved metals. In addition, the suspended materials were investigated for their elemental bulk composition.The particulate fractions represented from about 5% (Cd, Cu and Ni) to 50% (Fe and Pb) of the total (particulate plus dissolved) concentrations. For some elements (Ba, Cd, Cu, Pb and Zn), the particulate matter from the surface microlayer was enriched with respect to those suspended materials taken from 0.2 m depth. This could reflect the atmospheric input of metal-rich aerosols. In anoxic deep waters, maximum contents of Zn (6400 μg g⁻¹), Cu (1330 μg g⁻¹) and Cd (12 μg g⁻¹) were observed in the particulate matter, indicating sulphidic forms. On the other hand, under oxic conditions the distribution coefficients (K_d) decreased with the water depth (Cd, Fe and Pb).Relative to global background levels, the particulate matter contained metal “excesses” amounting to more than 90% of the total contents (Cd, Mn, Pb and Zn). Automated electron probe X-ray microanalysis (EPXMA) revealed that the elemental composition of sediments is mainly governed by post-depositional processes of early diagenesis and is only weakly related to the composition of suspended matter in the overlying water body. For instance, in relation to surface mud sediments of the central Baltic net-sedimentation basins, Zn, Cd, Cu and Mn had 30–100% higher levels in the suspended materials. The general pattern of metal contents of particulate matter taken from 10 m depth on a transect between the Bothnian Bay and the North Sea were—possibly as a result of anthropogenic inputs—rather similar for Pb, Zn and Cu. For Fe and Mn, the distribution patterns along the transect were probably governed by the natural loading characteristics and by the biogeochemistry of those elements.  相似文献   

Effect of dispersion on impulsive waves     

Shen Wang  Bernard le Mehaute  Chia-Chi Lu 《Marine Geophysical Researches》1987,9(1):95-111

The generation and propagation of surface waves resulting from suddenly created disturbances over water surfaces is investigated. The initial boundary conditions defining the disturbance are given either by a velocity of the free surface, an initial elevation of the free surface or a pressure impulsively applied on the free surface. It is shown that the corresponding three forms of solutions are related by a simple time derivative. Linear solutions are obtained in the cases where the wave motion is assumed to be nondispersive, mildly dispersive and fully dispersive, as well as in the case where the motion is given by the method of stationary phase. Criteria are established to indicate the limit of validity of each method.  相似文献   

The European coastal zone: characterization and first assessment of ecosystem metabolism     

Frdric Gazeau  Stephen V. Smith  Bernard Gentili  Michel Frankignoulle  Jean-Pierre Gattuso 《Estuarine, Coastal and Shelf Science》2004,60(4):673-694

The geomorphic, oceanographic, terrestrial and anthropogenic attributes of the European coastal zone are described and published data on ecosystem function (primary production and respiration) are reviewed. Four regions are considered: the Baltic Sea, Mediterranean Sea, Black Sea and the European Atlantic coast including the North Sea. The metabolic database (194 papers) suffers from a non-homogeneous geographical coverage with no usable data for the Black Sea which was therefore excluded from this part of our study. Pelagic gross primary production in European open shelves is, by far, the most documented parameter with an estimated mean of 41 mmol C m⁻² d⁻¹, the lowest value is reported in the Mediterranean Sea (21 mmol C m⁻² d⁻¹) and the highest one in the Atlantic/North Sea area (51 mmol C m⁻² d⁻¹). Microphytobenthic primary production, mostly measured in shallow areas, is extrapolated to the entire 0–200 m depth range. Its contribution to total primary production is low in all regions (mean: 1.5 mmol C m⁻² d⁻¹). Although macrophyte beds are very productive, a regional production estimate is not provided in this study because their geographical distribution along the European coastline remains unknown. Measurements of pelagic community respiration are clearly too sparse, especially below the euphotic zone, to yield an accurate picture of the fate of organic matter produced in the water column. With a mean value of 17 mmol C m⁻² d⁻¹, benthic community respiration consumes approximately 40% of the pelagic organic matter production. Estuaries generally exhibit high metabolic rates and a large range of variation in all parameters, except microphytobenthic primary production. Finally, the problem of eutrophication in Europe is discussed and the metabolic data obtained in the framework of the Land–Ocean Interactions in the Coastal Zone (LOICZ) project are compared with available direct measurements of net ecosystem production.  相似文献   

Some controversial issues in theories of the solar differential rotation and dynamo     

Bernard R. Durney 《Solar physics》1989,123(2):197-216

The following points are discussed:

(i)	The dependence of the angular velocity, , on the spatial coordinates near the lower boundary, R c, of the solar convection zone (SCZ) can be obtained from an integration with respect to r of a sound approximation to the azimuthal equation of motion. Here P 2 (cos ) is the second-order Legendre polynomial and is the polar angle. Estimates of 0, 2 (the primes denote derivatives with respect to r), based on the best available values for the Reynolds stresses and anisotropic viscosity coefficients, suggest that 0 < 0,=">2 0 for r = R c. Since a reliable theory of anisotropic turbulent coefficients does not exist at present, positive values of 0 are conceivable.
(ii)	In the lower SCZ the latitudinal variations of the superadiabatic gradient vanish if is constant along cylinders. The uniformity of the superadiabatic gradient is, however, inconsequential: the physically meaningful rotation law is the one that insures the uniformity of the convective flux.
(iii)	With the exception of the polar regions, the angular momentum transport in thin azimuthal convective rolls is towards the equator.
(iv)	It is suggested that buoyancy uncorrelates horizontally separated regions in the lower SCZ preventing the generation of magnetic fields with small wave numbers: in consequence, the cycle magnetic field must be generated in a region of weak buoyancy whereas the lower SCZ generates a weak rather stochastic magnetic field. The dependence on rotation of these two types of magnetic field could differ.
(v)	In the context of helioseismology it is customary to expand the perturbations (induced by rotation) of the eigenfrequencies in the following form: , where the notation is standard. The observations reveal that to a good approximation a 1 is independent of l. It is shown that this is the case if is constant with r. For a simple viscous, rotating fluid in the steady state (r) is constant with r if the angular momentum loss vanishes. Let J(ri dr) be the angular momentum of a thin shell of radius r and thickness dr. Since , the constancy of (r) implies that each shell of radius r has the same angular momentum as if the Sun were rotating uniformly with an angular velocity given by . It is discussed whether, alternatively, the observations simply indicate that 0(r) is a slowly varying function of r.

Operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation.  相似文献