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On The Differences Between Bubble-Mediated Air-Water Transfer In Freshwater And Seawater, W. E. Asher, L. M. Karle, B. J. Higgins Jan 1997

On The Differences Between Bubble-Mediated Air-Water Transfer In Freshwater And Seawater, W. E. Asher, L. M. Karle, B. J. Higgins

Journal of Marine Research

Bubble populations and gas transfer velocities were measured in cleaned and surfactant-influenced freshwater and seawater. A nonlinear fitting technique was used to partition the total gas transfer velocity for a gas in each water type into a turbulence- and bubble-mediated fraction. This showed that the bubble-mediated transfer fraction was larger in cleaned freshwater than in cleaned seawater and that the difference was a function of diffusivity and solubility. This was explained by the fact that the bubble measurements showed that bubble plumes in cleaned freshwater had a higher concentration of large bubbles and a lower concentration of small bubbles than …

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Instability In Stratified Rotating Shear Flow Along Ridges, G. A. Schmidt, E. R. Johnson Jan 1997

Instability In Stratified Rotating Shear Flow Along Ridges, G. A. Schmidt, E. R. Johnson

Journal of Marine Research

This paper examines the interaction between continuously stratified horizontal shear flow and topography. It investigates when topography whose slope changes sign (i.e., a ridge or a trench) destabilizes a shear flow. The instabilities have the form of topographic Rossby waves and rely on the background potential vorticity gradient to exist. Barotropic flow is examined in detail for general horizontal shear over stepped topography and the longwave stratified case is examined in the more specific case of linear shear flow over a top-hat ridge profile. In all cases modes are unstable over significant ranges of the relevant parameters. Stationary unstable modes …

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A Laboratory Study Of The Effects Of A Sloping Side Boundary On Wind-Driven Circulation In A Homogeneous Ocean Model, Ross W. Griffiths, George Veronis Jan 1997

A Laboratory Study Of The Effects Of A Sloping Side Boundary On Wind-Driven Circulation In A Homogeneous Ocean Model, Ross W. Griffiths, George Veronis

Journal of Marine Research

A laboratory model is used to investigate the effects of sloping boundaries on homogeneous wind-driven β-plane circulation. The very gentle slopes of real oceanic boundaries raise the possibility that dissipation by lateral diffusion of vorticity to the boundary is largely removed, leaving dissipation only in bottom Ekman layers. The laboratory model is a modification of the rotating ‘sliced-cylinder’ introduced by Pedlosky and Greenspan (1967) and Beardsley (1969) and in which flow is driven by a differentially rotating lid. The vertical wall is replaced with a side wall having a uniform 45° slope around the entire perimeter. This sloping boundary, like …

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On The Transition Between Different Dynamical Regimes Of The Antarctic Circumpolar Current, V. M. Kamenkovich Jan 1997

On The Transition Between Different Dynamical Regimes Of The Antarctic Circumpolar Current, V. M. Kamenkovich

Journal of Marine Research

Two different dynamical regimes of the Antarctic Circumpolar Current are considered: the Sverdrup regime and the frictionally controlled one. In the former the intensity of the current does not depend on friction, while in the latter it is inversely proportional to the coefficient of friction. The transition between these two regimes is studied. It is shown that the frictionally controlled regime is generated not only in the case of closed isolines of ambient potential vorticity q. The regime is formed in the case of blocked (or partially blocked) q isolines as well, if the slope of the q isolines …

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Benthic-Pelagic Coupling In Northern Gulf Of Mexico Estuaries: Do Benthos Feed Directly On Phytoplankton?, Gary R. Gaston, Carol M. Cleveland, Steven S. Brown, Chet F. Rakocinski Jan 1997

Benthic-Pelagic Coupling In Northern Gulf Of Mexico Estuaries: Do Benthos Feed Directly On Phytoplankton?, Gary R. Gaston, Carol M. Cleveland, Steven S. Brown, Chet F. Rakocinski

Gulf and Caribbean Research

Few of the dominant benthic taxa of the northern Gulf of Mexico feed directly on phytoplankton. Rather, most of them feed on near-bottom seston and detritus. This is in contrast to models for Chesapeake Bay and San Francisco Bay. We found that detritivores represented over 80% of the macrobenthic organisms and over 90% of the biomass in Gulf of Mexico estuaries. The paucity of benthos that consumed phytoplankton led us to hypothesize that macrobenthos in Gulf of Mexico estuaries had less effect on plankton communities than was documented in U.S. east coast and west coast estuaries, where benthic communities consumed …

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Monitoring The Upper Southeastern Atlantic Transports Using Altimeter Data, Silvia L. Garzoli, Gustavo J. Goñi, Arthur J. Mariano, Donald B. Olson Jan 1997

Monitoring The Upper Southeastern Atlantic Transports Using Altimeter Data, Silvia L. Garzoli, Gustavo J. Goñi, Arthur J. Mariano, Donald B. Olson

Journal of Marine Research

A large in-situ data set, collected in the southeastern Atlantic Ocean, is merged with the TOPEX/POSEIDON altimeter observations in order to verify the use of altimeter data in monitoring the transports of the Agulhas/Benguela system. Comparisons between altimeter observations and either moored current meters or inverted echo sounder measurements shows that the sea-surface elevation anomaly is significantly correlated with the thermocline depth and the surface dynamic height, respectively. Knowing the least-squares regression parameters, it is possible to calculate the transports by using geostrophy and either a two-layer or a continuously-stratified model. The transports obtained from fits of dynamic height to …

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Barotropic, Wind-Driven Circulation In A Small Basin, S. P. Meacham, P. S. Berloff Jan 1997

Barotropic, Wind-Driven Circulation In A Small Basin, S. P. Meacham, P. S. Berloff

Journal of Marine Research

We study the asymptotic behavior (large time) of a simple, wind-driven, barotropic ocean model, described by a nonlinear partial differential equation with two spatial dimensions. Considered as a dynamical system, this model has an infinite-dimensional phase space. After discretization, the equivalent numerical model has a phase space of finite but large dimension. We find that for a considerable range of friction, the asymptotic states are low-dimensional attractors. We describe the changes in the structure of these asymptotic attractors as a function of the eddy viscosity of the model. A variety of different types of attractor are seen, with chaotic attractors …

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The Hydrography And Circulation Of The Upper 1200 Meters In The Tropical North Atlantic During 1982-91, Gennady Chepurin, James A. Carton Jan 1997

The Hydrography And Circulation Of The Upper 1200 Meters In The Tropical North Atlantic During 1982-91, Gennady Chepurin, James A. Carton

Journal of Marine Research

We assemble a collection of 7591 conductivity-temperature-depth stations in the tropical Atlantic between 5S and 20N for the period 1982–1991 using data from the Soviet SECTIONS program enhanced by contributions primarily from the WESTRAX and FOCAL/SEQUAL programs. Most of the stations are west of 30W, forming a series of 21 surveys. In addition there were five multi-ship basinwide surveys, each taking 1.5–3 months to complete. The quality of the SECTIONS data is discussed and comparisons between the data sets are shown. Within the pycnocline, southern water is distinguished by salinity that is 0.3 psu lower than its northern counterpart at …

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Updated Bathymetry Of The Anegada-Jungfern Passage Complex And Implications For Atlantic Inflow To The Abyssal Caribbean Sea, David M. Fratantoni, Rainer J. Zantopp, William E. Johns, Jerry L. Miller Jan 1997

Updated Bathymetry Of The Anegada-Jungfern Passage Complex And Implications For Atlantic Inflow To The Abyssal Caribbean Sea, David M. Fratantoni, Rainer J. Zantopp, William E. Johns, Jerry L. Miller

Journal of Marine Research

Recent bathymetric, hydrographic and direct velocity measurements indicate that a previously unexplored deep passage in the northeastern Caribbean Sea may play a significant role in the abyssal ventilation of this basin. The Anegada-Jungfern Passage complex has long been recognized as the sole pathway for deep Atlantic inflow to the eastern Caribbean. The Anegada Passage (sill depth 1915 m) connects the Atlantic Ocean with the small Virgin Islands Basin, while Jungfern Passage (sill depth 1815 m) connects the latter with the large and deep Venezuela Basin comprising the eastern third of the Caribbean Sea. In the region of Jungfern Passage recent …

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Implications Of The Salt And Heat Budgets Of The Gulf Of Thailand, Kate Stansfield, Chris Garrett Jan 1997

Implications Of The Salt And Heat Budgets Of The Gulf Of Thailand, Kate Stansfield, Chris Garrett

Journal of Marine Research

Hydrographic data collected during 1959 and 1960 in the Gulf of Thailand, combined with supporting climatological data, have been used to investigate the salt and heat budgets of the Gulf. A simple model including mixing, net precipitation, local river run-off and Ekman flux predicts the flushing time of the Gulf, associated with processes other than the Ekman flux, to be 12.0 months, but predicts too small a magnitude and the wrong phase for the observed seasonal salinity cycle. Adding the discharge from the Mekong River reduces the flushing time to 5.4 months and improves the fit to the magnitude of …

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Morphological And Compositional Evidence For Biotic Precipitation Of Marine Barite, Miriam A. Bertram, James P. Cowen Jan 1997

Morphological And Compositional Evidence For Biotic Precipitation Of Marine Barite, Miriam A. Bertram, James P. Cowen

Journal of Marine Research

Barite formation in the surface oceans is generally assumed to be dominated by abiotic precipitation. Acceptance of this pathway is largely the result of the absence of a pelagic marine organism known to precipitate the ovoid to rounded-rectangular barite crystals typically observed in marine waters and sediments. Barite crystals observed in net-tow particles and on substrates retrieved from the seafloor (both in the central North Pacific) were examined by scanning electron microscopy and energy dispersive X-ray spectrometry. Three distinct crystalline forms of barite were observed: ovoid and hexagonal crystals several microns in diameter, and aggregates of submicron-sized crystals. Ovoid and …

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Sediment Resuspension Rates, Organic Matter Quality And Food Utilization By Sea Scallops (Placopecten Magellanicus) On Georges Bank, Jonathan Grant, Peter Cranford, Craig Emerson Jan 1997

Sediment Resuspension Rates, Organic Matter Quality And Food Utilization By Sea Scallops (Placopecten Magellanicus) On Georges Bank, Jonathan Grant, Peter Cranford, Craig Emerson

Journal of Marine Research

Benthic detritus, bacteria, and settled phytoplankton are transported into the water column by resuspension, potentially providing a high quality food source to suspension feeders. Two aspects of resuspension must be considered in relation to food supplies for suspension feeders: the flux of particles from the sediments to the water column and its food value. Sediment resuspension rates on Georges Bank and the role of resuspended sediment in the diet of sea scallops (Placopecten magellanicus) were determined in laboratory flume experiments and shipboard feeding experiments, respectively. Resuspended carbon flux was estimated from flume bedload transport rates and the mass …

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Distinct Year-To-Year Particle Flux Variations Off Cape Blanc During 1988-1991: Relation To Δ 18o-Deduced Sea-Surface Temperatures And Trade Winds, G. Fischer, B. Donner, V. Ratmeyer, R. Davenport, G. Wefer Jan 1996

Distinct Year-To-Year Particle Flux Variations Off Cape Blanc During 1988-1991: Relation To Δ 18o-Deduced Sea-Surface Temperatures And Trade Winds, G. Fischer, B. Donner, V. Ratmeyer, R. Davenport, G. Wefer

Journal of Marine Research

Particle fluxes measured from 1988 to 1991 adjacent to a coastal upwelling site off Cape Blanc showed significant interannual variability of fluxes and sea-surface temperatures (SST) deduced from stable oxygen isotope analysis of the planktonic foraminifera Globigerinoides ruber and, partly, of the pteropod Limacina inflata. For the duration of the study period, a decrease in the seasonality of SST's was observed, as well as a significant decrease in the average annual SST from 24.4° to 20.8°C. This cooling trend was mainly the effect of a drastic decrease in the summer to fall SST (from 27.2° to 21.8°C). In comparison, …

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The Role Of Mesoscale Hydrography On Microbial Dynamics In The Northeast Atlantic: Results Of A Spring Bloom Experiment, B. Karrasch, H. G. Hoppe, S. Ullrich, S. Podewski Jan 1996

The Role Of Mesoscale Hydrography On Microbial Dynamics In The Northeast Atlantic: Results Of A Spring Bloom Experiment, B. Karrasch, H. G. Hoppe, S. Ullrich, S. Podewski

Journal of Marine Research

During RV Meteor cruise No. 10 from May to June 1989 (JGOFS pilot study) bacterial and picocyanobacterial abundance, biomass, and bacterial production were estimated at two drift stations close to 47N, 20W and 58N, 20W in the northeast Atlantic. At 47N two different mesoscale hydrographic structures were sampled which divided the drift experiment into a cyclonic and an anticyclonic circulation phase. Transition from one phase to the next was clearly reflected by changes of the biological structure in the upper water column. Phytoplankton stocks maintained during the cyclonic phase were about 1.8 times higher than those of the anticyclonic phase …

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Biological Removal Of Fine-Grained Lithogenic Particles From A Large River Plume, M. J. Dagg, E. P. Green, B. A. Mckee, P. B. Ortner Jan 1996

Biological Removal Of Fine-Grained Lithogenic Particles From A Large River Plume, M. J. Dagg, E. P. Green, B. A. Mckee, P. B. Ortner

Journal of Marine Research

The pelagic tunicate, Oikopleura dioica, feeds by non-selectively filtering particles in the size range of 0.2–20 μm. In the northern Gulf of Mexico, particulate matter in this size range contains large amounts of fine-grained lithogenic material because of the influence of the Mississippi River. During May 1992, O. dioica populations filtered between 2 and 44% (mean = 20%) of the upper 5 m each day. The filtered lithogenic particles either remain in the oikopleurid house or are defecated in fecal pellets which have high sinking velocities. Either way, the larvacean populations significantly alter the fates of fine-grained lithogenic particles …

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Molecular Diversity Of The Copepod, Nannocalunus Minor: Genetic Evidence Of Species And Population Structure In The North Atlantic Ocean, Anna Bucklin, Todd C. Lajeunesse, Eva Curry, John Wallinga, Karen Garrison Jan 1996

Molecular Diversity Of The Copepod, Nannocalunus Minor: Genetic Evidence Of Species And Population Structure In The North Atlantic Ocean, Anna Bucklin, Todd C. Lajeunesse, Eva Curry, John Wallinga, Karen Garrison

Journal of Marine Research

The abundant calanoid copepod, Nannocalanus minor, is widespread from the Florida Straits (FS), throughout the Gulf Stream and the Sargasso Sea, to the eastern North Atlantic Ocean. Does the species represent a single, randomly-mating population across this extensive region, or does it comprise a number of genetically distinct populations or taxonomically distinct forms? What are patterns and pathways of dispersal of the copepod across the North Atlantic? These questions were addressed using population genetic analysis of DNA sequence variation of a 440 base-pair region of the mitochondrial 16S rRNA gene. This analysis separated N. minor into two genetically distinct …

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A High Resolution Camera System (Parca) For Imaging Particles In The Ocean: System Design And Results From Profiles And A Three-Month Deployment, Volker Ratmeyer, Gerold Wefer Jan 1996

A High Resolution Camera System (Parca) For Imaging Particles In The Ocean: System Design And Results From Profiles And A Three-Month Deployment, Volker Ratmeyer, Gerold Wefer

Journal of Marine Research

For direct optical measurement of abundance, concentration and size distribution of marine particles, a high-resolution camera system (ParCa) was designed to improve on similar systems used by Honjo et al. (1984), Asper (1987) and others. Imaging a probe volume of up to 37 1, smallest particles with diameters of 50 μm can be counted. The images provide information on particle size, shape and abundance either during profiling through the water column or while moored in a certain depth over time. Depth profiles were acquired between fall 1992 and late spring 1993 on R. V. Meteor cruises M22-1 and M23-3 …

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Seasonal Transport Variations Of The Wind-Driven Ocean Circulation In A Two-Layer Planetary Geostrophic Model With A Continental Slope, Toshihiro Sakamoto, Toshio Yamagata Jan 1996

Seasonal Transport Variations Of The Wind-Driven Ocean Circulation In A Two-Layer Planetary Geostrophic Model With A Continental Slope, Toshihiro Sakamoto, Toshio Yamagata

Journal of Marine Research

Using a simple two-layer planetary geostrophic model with a continental slope, the observed seasonal variation of the total transport of the Kuroshio is explained qualitatively for the first time in a quite concise way. During the period of weak winds in summer, the total transport is much larger than the nontopographic Sverdrup transport. This is because the joint effect of baroclinicity and bottom relief (so-called JEBAR) drives the barotropic flow with releasing the available potential energy accumulated in winter. In winter, on the other hand, the transport is much smaller than the nontopographic Sverdrup transport. This is mainly due to …

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Carbon Cycling In Mesohaline Chesapeake Bay Sediments 2: Kinetics Of Particulate And Dissolved Organic Carbon Turnover, Eric E. Roden, Jon H. Tuttle Jan 1996

Carbon Cycling In Mesohaline Chesapeake Bay Sediments 2: Kinetics Of Particulate And Dissolved Organic Carbon Turnover, Eric E. Roden, Jon H. Tuttle

Journal of Marine Research

Temporal and depth variations in benthic carbon metabolism rates were examined in relation to particulate organic carbon (POC) deposition rates and particulate and dissolved organic carbon degradation kinetics in two sediments from the mesohaline region of Chesapeake Bay. The depth distribution of a single pool of metabolizable POC (MPOC) in mid-Bay sediments was estimated by curve-fitting of dry weight POC profiles (“1-G” approach). Estimated MPOC pools accounted for 3–4% of total POC content in the upper 10 cm of sediment. First-order MPOC decay constants of ≈10 yr−1 during the warm season were estimated from the ratio of …

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The Role Of Turbulence In The Sedimentation Loss Of Pelagic Aggregates From The Mixed Layer, Javier Ruiz Jan 1996

The Role Of Turbulence In The Sedimentation Loss Of Pelagic Aggregates From The Mixed Layer, Javier Ruiz

Journal of Marine Research

A simple approach is presented to model the effect that turbulence has on the sedimentation loss of pelagic particles from the mixed layer. The approach consists in determining how turbulence affects their vertical distribution by splitting the solution of the advection-diffusion equation into two functions, one for the concentration of particles in the mixed layer and the other one reflecting the shape of the profile of particle concentration. The results of the paper indicate that the sedimentation flux is seriously underestimated if a uniform distribution of particles is assumed in the mixed layer when turbulence levels are low. A correction …

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Grid-Scale Instability Of Convective-Adjustment Schemes, Paola Cessi Jan 1996

Grid-Scale Instability Of Convective-Adjustment Schemes, Paola Cessi

Journal of Marine Research

Through a simple illustrative example, it is shown that instantaneous convective adjustment schemes, of the type used in general circulation models to parametrize nonhydrostatic convective processes, lead to the spontaneous emergence of the smallest resolved horizontal scale: the grid mode is unstable regardless of the strength of the horizontal diffusivity. Convective adjustment vertically mixes properties at each grid-point, irrespective of the horizontal distribution of such properties. Thus, horizontal spatial gradients are amplified by convective adjustment, as long as adjustment is faster than the horizontal diffusion (or advection) time between neighboring grid-points. In the example presented here, the grid-scale instability is …

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Spin-Down And The Dynamics Of Dense Pool Gyres In Shallow Seas, A. E. Hill Jan 1996

Spin-Down And The Dynamics Of Dense Pool Gyres In Shallow Seas, A. E. Hill

Journal of Marine Research

Isolated lenses or domes of dense (often cold) bottom water are found in many shelf seas and can be expected to induce significant baroclinic circulations. However, provided they have the correct thermal wind shear, many flow states can support a bottom dome structure, including: (a) an anticyclonically circulating dense dome overlain by a static surface layer or (b) cyclonic surface flow around a static dome. A one-dimensional, two-layer, quasi-geostrophic model is applied to a Gaussian vortex to argue that, on account of bottom friction in shelf seas, the bottom layer will spin down to rest over a time-scale of just …

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Water-Property Distributions Along An Eastern Pacific Hydrographic Section At 135w, Mizuki Tsuchiya, Lynne D. Talley Jan 1996

Water-Property Distributions Along An Eastern Pacific Hydrographic Section At 135w, Mizuki Tsuchiya, Lynne D. Talley

Journal of Marine Research

As part of the World Ocean Circulation Experiment, full-depth CTD/hydrographic measurements with high horizontal and vertical resolutions were made in June-August 1991 along a line extending from 34N to 33S at a nominal longitude of 135W with an additional short leg that connects it to the California coast roughly along 34N. The line spans the major part of the subtropical and intertropical circulation regime of the eastern North and South Pacific. The primary purpose of this paper is to present vertical sections of various properties from CTD and discrete water-sample measurements along this line and to give an overview of …

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Fluid Flow And Suspended Particulates As Determinants Of Polychaete Feeding Behavior, Michael J. Bock, Douglas C. Miller Jan 1996

Fluid Flow And Suspended Particulates As Determinants Of Polychaete Feeding Behavior, Michael J. Bock, Douglas C. Miller

Journal of Marine Research

We examined the interactive effects of fluid flow, bed characteristics and suspended load on the feeding behavior of four species of marine polychaetes. Two species of obligate deposit feeders (Marenzelleria viridis and Ampharete parvidentata) and two species of palp-coiling facultative suspension feeders (Spiochaetopterus oculatus and Spio setosa) were exposed to flow and sediment-bed treatments that served to decouple fluid flow and particle flux. We employed low (no particle transport), medium (transport of flocs only) and high (transport of sand) flow speeds in factorial treatments of natural sediment, winnowed bed (flocs removed), armored bed (no sand transport …

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The Solubility Pump Of Carbon In The Subtropical Gyre Of The North Atlantic, Michael J. Follows, Richard G. Williams, John C. Marshall Jan 1996

The Solubility Pump Of Carbon In The Subtropical Gyre Of The North Atlantic, Michael J. Follows, Richard G. Williams, John C. Marshall

Journal of Marine Research

The subduction of carbon is examined using abiotic models of the solubility pump in the subtropical gyre of the North Atlantic. The importance of the seasonal cycle of the mixed layer, and advection of carbon, is examined using sensitivity experiments with a Lagrangian model of the carbon system. The rate of subduction of carbon is found to be strongly influenced by the gradients in mixed-layer thickness over the gyre and, to a lesser extent, modified by the end of winter bias in the properties of subducted fluid. A seasonally-cycling geochemical model of the carbon system is then developed for the …

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Inertial Gyre Solutions From A Primitive Equation Ocean Model, Annalisa Griffa, Eric P. Chassignet, Victoria Coles, Donald B. Olson Jan 1996

Inertial Gyre Solutions From A Primitive Equation Ocean Model, Annalisa Griffa, Eric P. Chassignet, Victoria Coles, Donald B. Olson

Journal of Marine Research

A numerical exploration of inertial equilibrium states obtained with a primitive equation ocean model suggests that they can be described using statistical mechanics theory developed in the framework of quasi-geostrophy. The performance of the numerical model is first assessed with respect to the quasi-geostrophic model considering a series of experiments in the quasi-geostrophic range, in a closed basin with flat bottom and varying Rossby numbers. The results show that our model is consistent with the quasi-geostrophic model even in terms of dependence from boundary conditions and eddy viscosity values, and that the free surface contribution is negligible. As in the …

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Deducing Dynamic Properties From Simulated Hydrographic Data: Part I. Results From A Non-Eddy-Resolving Model, Huai-Min Zhang, Nelson G. Hogg Jan 1996

Deducing Dynamic Properties From Simulated Hydrographic Data: Part I. Results From A Non-Eddy-Resolving Model, Huai-Min Zhang, Nelson G. Hogg

Journal of Marine Research

Inverse models are widely used in oceanography. However, their reliability remains an open question, as comparison of inverse model results with real values of ocean parameters is difficult due to insufficient knowledge of the latter. The feasibility of extracting the ocean general circulation, mixing rates, as well as air-sea heat and freshwater fluxes from hydrographic data is studied by applying an inverse model to the CME (Community Modeling Effort) results where both the physics and parameter values are known. The inverse model assumes approximate thermal wind balance and steady state conservation laws for mass, heat, and salt, assumptions satisfied by …

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Plankton Production In Tidal Fronts: A Model Of Georges Bank In Summer, Peter J. S. Franks, Changsheng Chen Jan 1996

Plankton Production In Tidal Fronts: A Model Of Georges Bank In Summer, Peter J. S. Franks, Changsheng Chen

Journal of Marine Research

A two-dimensional (x,z) coupled physical-biological model of the plankton on Georges Bank during the summer was developed. The physical portion included a primitive-equation turbulence-closure model with topography-following σ coordinate. The biological model was a simple N-P-Z model. Tidal forcing at the model boundary generated a well-mixed region on the top of the bank, and strong tidal fronts at the bank edges. Biological fields were homogenized on the bank, while pronounced phytoplankton patches and horizontal gradients in properties developed in the fronts. The biomasses and fluxes of biological variables in the model agreed well with field estimates from Georges …

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The Classification And Structure Of Megafaunal Assemblages In The Venezuela Basin, Caribbean Sea, Kevin B. Briggs, Michael D. Richardson, David K. Young Jan 1996

The Classification And Structure Of Megafaunal Assemblages In The Venezuela Basin, Caribbean Sea, Kevin B. Briggs, Michael D. Richardson, David K. Young

Journal of Marine Research

Data from 23 benthic trawls collected from the Venezuela Basin (3411–5062 m water depth) indicate that megafauna are less abundant than in basins of similar depths in the Atlantic and are segregated by sedimentary province. Taxonomic assemblages, in terms of abundance and biomass, from three sites coincide with distinctions of sedimentary characteristics among the pelagic, hemipelagic and turbidite sedimentary provinces. Mollusks, decapods and fishes are most abundant in trawls collected from the pelagic and hemipelagic provinces and anemones and holothurians are most abundant in trawls collected from the turbidite province. Sponges dominate the biomass of fauna in trawls collected in …

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Unsteady Similarity Solutions And Oscillating Ocean Gyres, Neil R. Edwards Jan 1996

Unsteady Similarity Solutions And Oscillating Ocean Gyres, Neil R. Edwards

Journal of Marine Research

The effect of time-dependent forcing on steady solutions representing basin-scale flows is investigated. Analytical and numerical solutions are considered separately and compared. We first use symmetry methods to show how any steady solution of the ideal thermocline equations can be used to generate a family of unsteady solutions, via an arbitrary function of time α(t). The resulting time-dependent solutions correspond to distortion of the isopycnal surfaces by a velocity field which varies linearly in the three coordinate directions. Although the displacements are linear, the fluctuations can lead to a form of nonlinear streaming wherever the function α appears …

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