A note on the effects of a thin visco-elastic mud layer on small amplitude water-wave propagation     

Philip L.-F. Liu  I-Chi Chan 《Coastal Engineering》2007

In this note we investigated the effects of a thin visco-elastic mud layer on wave propagation. Within the framework of linear water-wave theory, analytical solutions are obtained for damping rate, dispersion relation between wave frequency and wave number, and velocity components in the water column and mud layer. The wave attenuation rate reaches a maximum value when the mud layer thickness is about the same as the mud boundary layer thickness. Heavier mud has a weaker effect on the wave damping. However, the wave attenuation rate does not always decrease as the elastic shear modulus increases. In the range of small values for elastic shear modulus, the wave attenuation can be amplified quite significantly. The current solutions are compared with experimental data with different wave conditions and mud properties. In general, good agreements are observed.  相似文献   

加里福尼亚南部岸外泥火山的甲烷成因方解石、13C亏损的双壳类贝壳以及气水合物     

James R Hein  徐明芝 《海洋地质前沿》2006,22(8):21-25

沿大陆边缘的气体和流体通量与构造—沉积过程和(产生冷泉、温泉和甲烷水合物的)物化条件有关(如Obzhirov等,2004)。我们对水合物进行了深入研究,因为它对块体坡移、能源、全球气候突然变化以及全球的碳质量平衡具有潜在的贡献。其中冷泉尤其重要,因为其与大的气体和流体通量、  相似文献   

Estimating the underwater light field from remote sensing of ocean color     

Cheng-Chien Liu  Richard L. Miller  Kendall L. Carder  Zhongping Lee  Eurico J. D’Sa  James E. Ivey 《Journal of Oceanography》2006,62(3):235-248

We present a new approach that incorporates two models to estimate the underwater light field from remote sensing of ocean color. The first employs a series of analytical, semi-analytical, and empirical algorithms to retrieve the spectrum of inherent optical properties (IOPs), including the absorption and the backscatter coefficients, from the spectrum of remote sensing reflectance. The second model computes the profile of photosynthetically available radiation E _0,PAR (z) for a vertically homogeneous water column using the information of the retrieved IOPs and the ambient optical environment. This computation is based on an improved look-up table technology that possesses high accuracy, comparable with the full solution of the radiative transfer equation, and meets the computational requirement of remote sensing application. This new approach was validated by in situ measurements and an extensive model-to-model comparison with a wide range of IOPs. We successfully mapped the compensation depth by applying this new approach to process the SeaWiFS imagery. This research suggests that E _0,PAR (z) can be obtained routinely from ocean-color data and may have significant implications for the estimation of global heat and carbon budget.  相似文献   

Meanders in the Antarctic Polar Frontal Zone and their impact on phytoplankton     

Mark R. Abbott  James G. Richman  Jasmine S. Nahorniak  Brett S. Barksdale 《Deep Sea Research Part II: Topical Studies in Oceanography》2001,48(19-20)

The Antarctic Polar Front is a complex set of meandering jets, which appear to support enhanced primary productivity. The US Joint Global Ocean Flux Study conducted a series of survey and process studies in part to study the processes regulating primary productivity in this high nutrient, low chlorophyll region. We deployed a set of surface velocity drifters, some of which were equipped with bio-optical sensors, to study the temporal and spatial scales of biological and physical processes in the Antarctic Polar Frontal Zone. There were two primary sets of deployments: November 1997 before the spring bloom and January 1998 after the spring bloom. The November deployment revealed a strong spring bloom that lasted about 10 days. In late spring, when incoming solar radiation began to increase, the vertical motions associated with the meanders strongly affected the accumulation of phytoplankton biomass, primarily through their impact on light availability. Weaker meandering was observed in the January deployment, and chlorophyll values remained relatively constant. As the bloom began to decay, it appears that nutrient availability became more important in regulating phytoplankton photosynthesis. Some of the drifters in the November deployment were deployed in coherent clusters, thus allowing us to calculate vertical velocities associated with the meanders. Estimates of fluorescence/chlorophyll suggest that areas of upwelling and downwelling alternately decrease and increase photosynthetic stress, perhaps as a result of changes in the availability of iron or light during the formation of the bloom.  相似文献   

A social scientist's perspective on the Census of Marine Life   总被引：1，自引：0，他引：1  

James N. Sanchirico   《Marine Policy》2005,29(6):143-520

Over 300 natural scientists in 53 nations are taking part in the Census of Marine Life (CoML) to investigate what lived, what lives, and what will live in the oceans. The CoML is a scientific experiment that is exploring the limits of ocean science. The paper discusses the potential applications of CoML research and the mechanisms by which the potential benefits can be measured and preserved. I recommend developing and integrating policy advisory committees with the natural science activities to both maximize the benefits of the research and to avoid unintended consequences.  相似文献   

JGOFS studies in the equatorial Pacific     

James W. Murray  Robert Leborgnelt  Yves Dandonneau 《Deep Sea Research Part II: Topical Studies in Oceanography》1997,44(9-10)

This special issue is the third and final volume containing results from the JGOFS Process Study in the equatorial Pacific. Most of the Study in the equational Pacific. Most of the contributions evolved either from the US JGOFS workshop in 1994 on the equatorial Pacific in Scottsdale, AZ or from the NATO Advanced Research Workshop on the Carbon Cycle of the Equatorial Pacific in 1995 in Noumea, New Caledonia.  相似文献   

Advances in Vent, Seep, Whale- and Wood-Fall Biology     

Lisa A. Levin  James P. Barry  Horst Felbeck  Craig R. Smith  & Craig M. Young 《Marine Ecology》2007,28(1):1-2

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Winter-spring phytoplankton blooms in Dabob Bay, Washington   总被引：4，自引：2，他引：4  

Rita A. Horner  James R. Postel  Claudia Halsband-Lenk  James J. Pierson  Georg Pohnert  Thomas Wichard 《Progress in Oceanography》2005,67(3-4):286

Scientific investigations in Dabob Bay, Washington State, USA, have been extensive since the early 1960s, but phytoplankton blooms have been studied mostly with regard to chlorophyll concentrations and little is known about the phytoplankton species themselves. Here we provide information on the species present, their abundances during blooms, their contribution to organic carbon concentrations and the ability of some phytoplankton species to produce toxic aldehydes that may impact metazoan grazers.Multiple blooms of phytoplankton, dominated by diatoms, occurred in the late winter-early spring period, with depth-integrated chlorophyll levels ranging from <20 to 230 mg m⁻² and peaks in February and April. The major bloom species included Skeletonema costatum, Thalassiosira spp. and Chaetoceros spp; Phaeocystis cf. pouchetii occurred in 2002 and 2004. Other taxa or groups of organisms that were sometimes abundant included unidentified small flagellates <10 μm in size and unidentified heterotrophic dinoflagellates. Large diatoms usually comprised most of the cell carbon, but a large, heterotrophic dinoflagellate, identified only as Gyrodinium “tear” because of its shape, was a major contributor to the microplankton carbon when present even in small numbers. Five Thalassiosira species and S. costatum were found to produce polyunsaturated aldehydes (PUA) that are known to affect copepod reproduction and hatching success. Our findings are similar to the few previous studies in the last four decades that included phytoplankton species and suggest long-term similarities and relative stability in the phytoplankton species present and their timing in Dabob Bay.  相似文献   

Documenting hurricane impacts on coral reefs using two-dimensional video-mosaic technology     

Arthur C. R. Gleason  Diego Lirman  Dana Williams  Nuno R. Gracias  Brooke E. Gintert  Hossein Madjidi  R. Pamela Reid  G. Chris Boynton  Shahriar Negahdaripour  Margaret Miller  & Philip Kramer 《Marine Ecology》2007,28(2):254-258

Four hurricanes impacted the reefs of Florida in 2005. In this study, we evaluate the combined impacts of hurricanes Dennis, Katrina, Rita, and Wilma on a population of Acropora palmata using a newly developed video‐mosaic methodology that provides a high‐resolution, spatially accurate landscape view of the reef benthos. Storm damage to A. palmata was surprisingly limited; only 2 out of 19 colonies were removed from the study plot at Molasses Reef. The net tissue losses for those colonies that remained were only 10% and mean diameter of colonies decreased slightly from 88.4 to 79.6 cm. In contrast, the damage to the reef framework was more severe, and a large section (6 m in diameter) was dislodged, overturned, and transported to the bottom of the reef spur. The data presented here show that two‐dimensional video‐mosaic technology is well‐suited to assess the impacts of physical disturbance on coral reefs and can be used to complement existing survey methodologies.  相似文献   

Modelling and optimal control: a case study based on the Spencer Gulf prawn fishery for Penaeus latisulcatus Kishinouye     

Sluczanowski  Philip R. 《ICES Journal of Marine Science》1984,41(3):211-225

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