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North Pacific Internal Tides From The Aleutian Ridge: Altimeter Observations And Modeling, Patrick F. Cummins, Josef Y. Cherniawsky, Michael G. G. Foreman Jan 2001

North Pacific Internal Tides From The Aleutian Ridge: Altimeter Observations And Modeling, Patrick F. Cummins, Josef Y. Cherniawsky, Michael G. G. Foreman

Journal of Marine Research

Internal tides radiating into the North Pacific from the Aleutian Ridge near Amukta Pass are examined using 7 years of Topex/Poseidon altimeter data. The observations show coherent southward phase propagation at the M2 frequency over a distance of at least 1100 km into the central Pacific. Barotropic and baroclinic models are applied to study this internal tidal signal. Results from the barotropic model show that the strongest cross-slope volume and energy fluxes occur in the vicinity of Amukta Pass, helping to establish this region as an important site for baroclinic energy conversion along the eastern half of the ridge. …

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Internal And Interfacial Tides: Beam Scattering And Local Generation Of Solitary Waves, Theo Gerkema Jan 2001

Internal And Interfacial Tides: Beam Scattering And Local Generation Of Solitary Waves, Theo Gerkema

Journal of Marine Research

Analytical solutions of a linear internal-tide generation problem are presented for a stratification that involves both an interface (thermocline) and a lower layer of constant stratification. It is shown that an internal tidal beam scatters strongly at a moderately developed thermocline but much less at a thermocline that is either very weak or very strong. This scattering goes along with a local wave activity at the thermocline as well as with a downward leaking from the thermocline. It is argued that these processes offer a clue to explaining observations in the Bay of Biscay of 'local generation' of internal soliton …

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The Impact Of Model Configuration In Studies Of Buoyant Coastal Discharge, Richard W. Garvine Jan 2001

The Impact Of Model Configuration In Studies Of Buoyant Coastal Discharge, Richard W. Garvine

Journal of Marine Research

Observations and model studies of large-scale buoyant plumes show three major types for the horizontal distribution of density. Type 1 represents the typical coastal freshwater plume of observations. The buoyant discharge turns right in the northern hemisphere (toward downshelf) under earth rotation at its source. Type 2 is common in many numerical model studies. Most of the buoyant water at the inlet turns left (upshelf) along the coast to form a continuously growing intrusion. Type 3 turns right but exhibits a massive anticyclonic bulge which grows with time; its coastal current is weak and carries a small fraction of the …

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The Evolution And Energetics Of Large Amplitude Nonlinear Internal Waves On The Portuguese Shelf, D. R. G. Jeans, T. J. Sherwin Jan 2001

The Evolution And Energetics Of Large Amplitude Nonlinear Internal Waves On The Portuguese Shelf, D. R. G. Jeans, T. J. Sherwin

Journal of Marine Research

Intensive in-situ observations of nonlinear internal waves on the Portuguese shelf were made in August 1994, including measurements of the same wavepacket at three locations as it propagated on-shelf. The waves were characterized by sudden isotherm depressions of up to 45 m lasting 10-35 minutes, accompanied by current surges of up to 0.45 m s-1 and shears of up to 0.7 m s-1 over 60 m. The waves propagated away from the shelf break with an estimated phase speed of 0.57 m s-1. The amplitude of the waves was comparable to the theoretical maximum. The kinetic …

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Barotropic Instabilities Of The Agulhas Current System And Their Relation To Ring Formation, Henk A. Dijkstra, Wilhelmus P. M. De Ruijter Jan 2001

Barotropic Instabilities Of The Agulhas Current System And Their Relation To Ring Formation, Henk A. Dijkstra, Wilhelmus P. M. De Ruijter

Journal of Marine Research

Recent work has shown that different steady retroflection regimes, a viscous and an inertial regime, exist for the Agulhas Current system in an idealized geometry. In this paper, instabilities of the barotropic steady flows are considered by solving the linear stability problem numerically. Barotropic instabilities occur as so-called Hopf bifurcations in the viscous regime, with corresponding patterns related to Rossby basin modes. Depending on the value of the reduced gravity parameter, these instabilities may introduce intermonthly to interannual variability into the retroflection region. Finite amplitude development of these instabilities display 'ring-like' localized anomaly patterns which travel around the tip of …

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On The Summer Mesoscale Variability Of The Black Sea, Şükrü T. Beşiktepe, Carlos J. Lozano, Allan R. Robinson Jan 2001

On The Summer Mesoscale Variability Of The Black Sea, Şükrü T. Beşiktepe, Carlos J. Lozano, Allan R. Robinson

Journal of Marine Research

The evolution of the Black Sea temperature, salinity and circulation, from large scale to mesoscale, is studied using a data-driven primitive equation simulation. The data are drawn from (i) a basin-wide hydrographic survey, CoMSBlack'92, obtained in the Summer of 1992; (ii) wind stress derived from wind analyses of the Sevastopol MSIA/URHI Office; (iii) climatological heat fluxes; and (iv) climatological river outflows. The primitive equation model is from the Harvard Ocean Prediction System. The simulation is used to examine the evolution of the circulation at mesoscale resolution, its dominant variabilities and dependencies in the summer period. The large-scale upper layer circulation …

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The Origin Of Low-Frequency Variability Of Double-Gyre Wind-Driven Flows, Janine J. Nauw, Henk A. Dijkstra Jan 2001

The Origin Of Low-Frequency Variability Of Double-Gyre Wind-Driven Flows, Janine J. Nauw, Henk A. Dijkstra

Journal of Marine Research

Bifurcation analysis on flows in a two-layer shallow-water model is used to clarify the dynamical origin of low-frequency variability of the double-gyre wind-driven ocean circulation. In many previous model studies, generic low-frequency variations appear to be associated with distinct regimes, characterized by the level of kinetic energy of the mean flow. From these transient flow computations, the current view is that these regimes, and transitions between them, arise through a complex nonlinear interaction between the mean flow and its high-frequency instabilities (the eddies). On the contrary, we demonstrate here, for a particular (but relevant) case, that the origin of these …

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Impact Of Sub-Mesoscale Physics On Production And Subduction Of Phytoplankton In An Oligotrophic Regime, Marina Lévy, Patrice Klein, Anne-Marie Treguier Jan 2001

Impact Of Sub-Mesoscale Physics On Production And Subduction Of Phytoplankton In An Oligotrophic Regime, Marina Lévy, Patrice Klein, Anne-Marie Treguier

Journal of Marine Research

Using a protocol of numerical experiments where horizontal resolution is progressively increased, we show that small-scale (or sub-mesoscale) physics has a strong impact on both mesoscale physics and phytoplankton production/subduction. Mesoscale and sub-mesoscale physics result from the nonlinear equilibration of an unstable baroclinic jet. The biogeochemical context is oligotrophy. The explicitly resolved sub-mesoscales, at least smaller than one fifth of the internal Rossby radius of deformation, reinforce the mesoscale eddy field and contribute to double the primary production and phytoplankton subduction budgets. This enhancement is due to the reinforced mesoscale physics and is also achieved by the small-scale frontal dynamics. …

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A Bifurcation Study Of The Three-Dimensional Thermohaline Ocean Circulation: The Double Hemispheric Case, Wilbert Weijer, Henk A. Dijkstra Jan 2001

A Bifurcation Study Of The Three-Dimensional Thermohaline Ocean Circulation: The Double Hemispheric Case, Wilbert Weijer, Henk A. Dijkstra

Journal of Marine Research

Within a low-resolution primitive-equation model of the three-dimensional ocean circulation, a bifurcation analysis is performed of double-hemispheric basin flows. Main focus is on the connection between results for steady two-dimensional flows in a nonrotating basin and those for three-dimensional flows in a rotating basin. With the use of continuation methods, branches of steady states are followed in parameter space and their linear stability is monitored. There is a close qualitative similarity between the bifurcation structure of steady-state solutions of the two- and three dimensional flows. In both cases, symmetry-breaking pitchfork bifurcations are central in generating a multiple equilibria structure. The …

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Particle Flux In The Rainbow Hydrothermal Vent Field (Mid-Atlantic Ridge): Dynamics, Mineral And Biological Composition, Alexis Khripounoff, Annick Vangriesheim, Philippe Crassous, Michel Segonzac, Ana Colaço, Daniel Desbruyères, Roxane Barthelemey Jan 2001

Particle Flux In The Rainbow Hydrothermal Vent Field (Mid-Atlantic Ridge): Dynamics, Mineral And Biological Composition, Alexis Khripounoff, Annick Vangriesheim, Philippe Crassous, Michel Segonzac, Ana Colaço, Daniel Desbruyères, Roxane Barthelemey

Journal of Marine Research

In order to provide information about the export and the distribution of hydrothermal particulate material to the surrounding deep ocean, four moorings were deployed in the vicinity of the hydrothermal Rainbow vent field (Mid-Atlantic Ridge, 36°14′N, 2250 m depth). The first mooring was a sediment trap with a current meter deployed at 2 m from a chimney of the Rainbow vent field and 1.5 m above the bottom (a.b.) for 16 days. It represented the reference for the initial composition of particles produced by the vent. The total mean mass particle flux (6.9 g m-2 d-1) was …

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Mechanism Of Offshore Nutrient Supply In The Western Arabian Sea, Michio Kawamiya Jan 2001

Mechanism Of Offshore Nutrient Supply In The Western Arabian Sea, Michio Kawamiya

Journal of Marine Research

The mechanism to maintain the high surface chlorophyll in the western Arabian Sea during the southwest monsoon (SWM) season is studied with an eddy-permitting, biological-physical coupled model. Using a set of artificial tracers, it is revealed that horizontal transport of nutrient subsequent to the coastal upwelling is by far more important than the open ocean upwelling due to the Ekman pumping. The horizontal transport can be classified into three processes, the Ekman transport, transport by the large-scale circulation and that by the mesoscale currents. In the model, the first has only a minor effect within the area of high chlorophyll …

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The Role Of Colonization In Establishing Patterns Of Community Composition And Diversity In Shallow-Water Sedimentary Communities, Paul V. R. Snelgrove, J. Frederick Grassle, Judith P. Grassle, Rosemarie F. Petrecca, Karen I. Stocks Jan 2001

The Role Of Colonization In Establishing Patterns Of Community Composition And Diversity In Shallow-Water Sedimentary Communities, Paul V. R. Snelgrove, J. Frederick Grassle, Judith P. Grassle, Rosemarie F. Petrecca, Karen I. Stocks

Journal of Marine Research

To determine whether pattern and diversity in benthic sedimentary communities are set primarily at colonization or by post-settlement biological interactions, we collected faunal cores and conducted reciprocal sediment transplant experiments at a sandy and a muddy site at 12 m depth, ~3 km apart off New Jersey. Multivariate analyses of cores collected at these sites in September 1994 indicated differences in the taxa determining local pattern, with the bivalve Spisula solidissima and the polychaete Polygordius sp. being dominant at the sandy site, and oligochaetes, several polychaete species and the bivalve Nucula annulata dominant at the muddy site. Individual cores from …

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Phytoplankton Seasonal Distribution From Seawifs Data In The Agulhas Current System, E. Machu, V. Garçon Jan 2001

Phytoplankton Seasonal Distribution From Seawifs Data In The Agulhas Current System, E. Machu, V. Garçon

Journal of Marine Research

The interocean conduit for warm Indian Ocean water into the Atlantic Ocean is the Agulhas system which plays an important role in maintaining the global thermohaline circulation. The frontal system formed by the Agulhas Return Current (ARC) and the Subtropical Convergence (STC) is also a region of intense mesoscale activity presenting enhanced levels of biological production and chlorophyll a. We jointly analyzed three different satellite data sets to relate the remotely sensed distribution of phytoplankton (SeaWiFS ocean color data) to the dynamical environment (Topex/Poséidon-ERS sea level anomalies-SLA- and sea-surface temperature-SST-) to gain insight into the seasonal behavior of the …

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A Data Assimilative Marine Ecosystem Model Of The Central Equatorial Pacific: Numerical Twin Experiments, Marjorie A. M. Friedrichs Jan 2001

A Data Assimilative Marine Ecosystem Model Of The Central Equatorial Pacific: Numerical Twin Experiments, Marjorie A. M. Friedrichs

Journal of Marine Research

A five-component, data assimilative marine ecosystem model is developed for the high-nutrient low-chlorophyll region of the central equatorial Pacific (0N, 140W). Identical twin experiments, in which model-generated synthetic 'data' are assimilated into the model, are employed to determine the feasibility of improving simulation skill by assimilating in situ cruise data (plankton, nutrients and primary production) and remotely-sensed ocean color data. Simple data assimilative schemes such as data insertion or nudging may be insufficient for lower trophic level marine ecosystem models, since they require long time-series of daily to weekly plankton and nutrient data as well as adequate knowledge of the …

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Central Equatorial Pacific Zonal Currents. I: The Sverdrup Balance, Nonlinearity And Tropical Instability Waves. Annual Mean Dynamics, D. E. Harrison, R. D. Romea, S. H. Hankin Jan 2001

Central Equatorial Pacific Zonal Currents. I: The Sverdrup Balance, Nonlinearity And Tropical Instability Waves. Annual Mean Dynamics, D. E. Harrison, R. D. Romea, S. H. Hankin

Journal of Marine Research

Several recent observational studies of central Pacific equatorial current dynamics have suggested that, in the vertical integral between the surface and the thermocline, the linear equatorial Sverdrup balance holds. However, in a high vertical resolution ocean general circulation model, we find that nonlinearity is an order (1) element of the local and the vertically integrated balances on and near the equator at 140W. Although this OGCM has been used in many studies of the tropical Pacific, its equatorial zonal momentum equation balances have never been described in detail and compared with observations. We describe the annual mean balances here, identify …

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The Impact Of Model-Error Correlation On Regional Data Assimilative Models And Their Observational Arrays, Philip S. Bogden Jan 2001

The Impact Of Model-Error Correlation On Regional Data Assimilative Models And Their Observational Arrays, Philip S. Bogden

Journal of Marine Research

Data assimilative models often minimize a penalty functional that measures model adjustment and model-data misfit. The penalty functional builds assumptions about model error into the analysis. Usually, errors from different parts of the model (e.g., dynamics and boundary conditions) are presumed to be uncorrelated. This is clearly not a valid assumption in regional models where uncertain large-scale forcing affects open-ocean boundary conditions. In this study, calculations with a regional wind-driven inverse model provide a specific example where model error from uncertain wind stress is correlated with model error from uncertain open boundary conditions. This physically realistic scenario motivates development of …

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The Near-Surface Velocity And Potential Vorticity Structure Of The Gulf Stream, T. Rossby, H. M. Zhang Jan 2001

The Near-Surface Velocity And Potential Vorticity Structure Of The Gulf Stream, T. Rossby, H. M. Zhang

Journal of Marine Research

Using Acoustic Doppler Current Profiler and XBT data between 1992 and 1999 from a container vessel that crosses the Gulf Stream twice weekly near 70W, we examine the near-surface velocity, thermal and vorticity structure of the current. These data come from an ongoing sampling program that has as its overall objective to measure the currents between New York and Bermuda to provide a high-quality database for studies of variability and long-term trends in the region. These Gulf Stream sections, when averaged in natural or stream coordinates, exhibit a remarkable double-exponential structure. The scale-widths of the lateral shear north and south …

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Effects Of Topography On The Beta-Drift Of A Baroclinic Vortex, Georgi Sutyrin Jan 2001

Effects Of Topography On The Beta-Drift Of A Baroclinic Vortex, Georgi Sutyrin

Journal of Marine Research

The propagation of compact, surface-intensified vortices over a topographic slope on the beta-plane is studied in the framework of a two-layer model. A perturbation theory is derived for a circular vortex in the upper layer with the lower layer at rest as a basic state. An integral momentum balance for the upper layer is used to obtain expressions for the velocity of the vortex center assuming the flow is quasi-stationary to leading order. This approach allows the calculation of the lower-layer flow pattern as a function of the interface shape and the slope orientation. The essential part of the lower-layer …

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Modeling Water Column Structure And Suspended Particulate Matter On The Middle Atlantic Continental Shelf During The Passages Of Hurricanes Edouard And Hortense, Alejandro J. Souza, Tommy D. Dickey, Grace C. Chang Jan 2001

Modeling Water Column Structure And Suspended Particulate Matter On The Middle Atlantic Continental Shelf During The Passages Of Hurricanes Edouard And Hortense, Alejandro J. Souza, Tommy D. Dickey, Grace C. Chang

Journal of Marine Research

The present contribution is motivated by the desire to elucidate the processes that contributed to the evolution of observed thermal structure and resuspension of particulate matter during and after the passages of two hurricanes, Edouard and Hortense, within a two-week period in late-summer 1996. A unique set of high temporal frequency measurements of the vertical structures of physical and optical properties was obtained at a mooring site near the Middle Atlantic Bight continental shelf-break (70 m water depth). These data provided insight and initial conditions for the physical model used for this study. The model accounted for wind and bottom …

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Particle Trapping In A Stratified Flood-Dominated Estuary, Robert J. Chant, Allan W. Stoner Jan 2001

Particle Trapping In A Stratified Flood-Dominated Estuary, Robert J. Chant, Allan W. Stoner

Journal of Marine Research

Observations in the Navesink River estuary in northern New Jersey demonstrate that buoyancy augments the particle trapping tendencies of flood-dominated systems because these estuaries heighten tidal period asymmetries in stratification. During the long and slow ebb which typifies flood-dominated systems, a positive feedback between tidal straining and weak vertical mixing stratifies the estuary. In contrast, during flood, turbulence generated by the stronger tidal currents augments overstraining of the density field and the water column becomes well mixed. The tidal period asymmetries in stratification have profound effects on the vertical structure and transport of suspended matter. During ebb, weak vertical mixing …

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Performance Of Cages As Large Animal-Exclusion Devices In The Deep Sea, James E. Eckman, David Thistle, William C. Burnett, Gordon L. J. Paterson, Charles Y. Robertson, P. John D. Lambshead Jan 2001

Performance Of Cages As Large Animal-Exclusion Devices In The Deep Sea, James E. Eckman, David Thistle, William C. Burnett, Gordon L. J. Paterson, Charles Y. Robertson, P. John D. Lambshead

Journal of Marine Research

Sedimentary, deep-sea communities include megafaunal animals (e.g., sea cucumbers, brittle stars, crabs) and demersal fishes, collectively termed the large, motile epifauna (LME). Individuals of the LME are common, and their biomass approximates that of the macrofauna. Based on analogies with shallow-water animals, they are likely to be sources of mortality for the infauna and to create spatial and temporal heterogeneity in the community. Given present theories of deep-sea community organization, such effects could be important. Unfortunately, this hypothesis has not been tested because of the difficulty of conducting experiments in the deep sea and because tools for manipulating the LME …

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Assessing The Dispersal And Exchange Of Brachyuran Larvae Between Regions Of San Diego Bay, California And Nearshore Coastal Habitats Using Elemental Fingerprinting, Claudio Dibacco, D. Bart Chadwick Jan 2001

Assessing The Dispersal And Exchange Of Brachyuran Larvae Between Regions Of San Diego Bay, California And Nearshore Coastal Habitats Using Elemental Fingerprinting, Claudio Dibacco, D. Bart Chadwick

Journal of Marine Research

Marine benthic invertebrate populations found in estuarine or coastal habitats often exchange larvae. However, the dynamics of larval exchange are poorly understood because of difficulties in (1) making synoptic assessments of horizontal and vertical larval distribution patterns over large areas for extended periods of time and (2) determining the origins of field-sampled larvae. This study examines how temporal changes in the vertical and horizontal distribution of crab larvae (i.e., Pachygrapsus crassipes and Lophopanopeus spp.) affect larval transport. Larval concentration and water velocity data were collected concurrently and were used to estimate larval exchange between regions of San Diego Bay (SDB) …

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A Particle Introduction Experiment In Santa Catalina Basin Sediments: Testing The Age-Dependent Mixing Hypothesis, William L. Fornes, David J. Demaster, Craig R. Smith Jan 2001

A Particle Introduction Experiment In Santa Catalina Basin Sediments: Testing The Age-Dependent Mixing Hypothesis, William L. Fornes, David J. Demaster, Craig R. Smith

Journal of Marine Research

The occurrence of "age-dependent mixing," a process by which recently deposited, food-rich particles undergo more intense bioturbation than older, food-poor particles, could dramatically alter patterns of organic-matter diagenesis in deep-sea sediments. To explicitly test for age-dependent mixing, an in-situ particle introduction experiment was conducted on the bathyal Santa Catalina Basin floor. Mixtures of radioisotope-tagged particles representing a food quality gradient were dispersed in small amounts on the seafloor and sampled over periods of 0 to 594 days. Introduced particle types were all similar in size and included fresh diatoms ("young" particles), surface sediments ("intermediate-age" particles), and particles from 30-cm deep …

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Dynamics Of The Makassar Strait, Jorina M. Waworuntu, Silvia L. Garzoli, Donald B. Olson Jan 2001

Dynamics Of The Makassar Strait, Jorina M. Waworuntu, Silvia L. Garzoli, Donald B. Olson

Journal of Marine Research

Data collected as part of the Arlindo Project ("Arlindo" is an acronym for Arus Lintas Indonesia, meaning "throughflow" in Bahasa Indonesia) from October 1996 to March 1998 are analyzed to study the characteristics of the flow through the Makassar Strait. Analysis of inverted echo sounders (IES) and bottom pressure data (PIES) combined with TOPEX/POSEIDON satellite-derived sea height anomaly suggest that a minimum of three-layer approximation is necessary to explain the dynamics of the flow in the Makassar Strait. The simple two-layer model used in several studies of the throughflow is rejected based on total incompatibility with the data sets. A …

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Salt Fingers In An Unbounded Thermocline, Melvin E. Stern, Timour Radko, Julian Simeonov Jan 2001

Salt Fingers In An Unbounded Thermocline, Melvin E. Stern, Timour Radko, Julian Simeonov

Journal of Marine Research

Numerical solutions for salt fingers in an unbounded thermocline with uniform overall vertical temperature-salinity gradients are obtained from the Navier-Stokes-Boussinesq equations in a finite computational domain with periodic boundary conditions on the velocity. First we extend previous two-dimensional (2D) heat-salt calculations [Prandtl number Pr = ν/kT = 7 and molecular diffusivity ratio τ = kS/kT = 0.01] for density ratio R = 2; as R decreases we show that the average heat and salt fluxes increase rapidly. Then three-dimensional (3D) calculations for R = 2.0, Pr = 7, and the numerically "accessible" values of τ …

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Observations Of The Wind-Induced Exchange At The Entrance To Chesapeake Bay, Arnoldo Valle-Levinson, Kuo-Chuin Wong, Kathryn T. Bosley Jan 2001

Observations Of The Wind-Induced Exchange At The Entrance To Chesapeake Bay, Arnoldo Valle-Levinson, Kuo-Chuin Wong, Kathryn T. Bosley

Journal of Marine Research

Water density and velocity data from two ~75-day deployments across the entrance to the Chesapeake Bay were used in conjunction with wind velocity and sea level records to describe the transverse structure of wind-induced subtidal exchange. Acoustic Doppler current profilers, electromagnetic current meters, and conductivity-temperature-depth recorders were deployed at the entrance to the bay from mid-April to early July of 1999 and from early September to mid-November of 1999. Three main scenarios of wind-induced exchange were identified: (1) Northeasterly (NE) winds consistently drove water from the coast toward the lower Chesapeake Bay as well as water from the upper bay …

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Horizontal Dispersion Of Near-Inertial Oscillations In A Turbulent Mesoscale Eddy Field, Patrice Klein, Stefan Llewellyn Smith Jan 2001

Horizontal Dispersion Of Near-Inertial Oscillations In A Turbulent Mesoscale Eddy Field, Patrice Klein, Stefan Llewellyn Smith

Journal of Marine Research

We study the dispersion of wind-induced near-inertial oscillations (NIOs) in a fully turbulent baroclinic mesoscale eddy field characterized by a continuous wavenumber spectrum. The influence of the eddy field on the horizontal dispersion of the different NIO modes is analyzed using a vertical normal mode expansion. Previous studies have identified two dispersion regimes: trapping and strong dispersion. We examine the modes in physical and spectral space to assess which regime prevails. Numerical and analytical results show the prevalence of a trapping regime. For each NIO mode, there exists a critical horizontal wavenumber, kc, that separates large-scale NIO structures, …

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Central Equatorial Pacific Zonal Currents. Ii: The Seasonal Cycle And The Boreal Spring Surface Eastward Surge, D. E. Harrison, R. D. Romea, G. A. Vecchi Jan 2001

Central Equatorial Pacific Zonal Currents. Ii: The Seasonal Cycle And The Boreal Spring Surface Eastward Surge, D. E. Harrison, R. D. Romea, G. A. Vecchi

Journal of Marine Research

The seasonally averaged zonal momentum equation tendencies at 140W are studied in a high-resolution primitive equation ocean general circulation model simulation of the tropical Pacific. The model experiment, forced by climatological monthly average wind-stress, reproduces well the observed boreal springtime eastward surge of the normally westward surface flow, as well as many features of the acceleration and deceleration between the surface and 200 m between January and October. We present each of the zonal momentum equation tendency terms for the depth range 0-160 m, but our discussion focuses on the behavior of the boreal springtime near-surface flow, perhaps the most …

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Effects Of Macrofauna On Acoustic Backscatter From The Seabed: Field Manipulations In West Sound, Orcas Island, Washington, U.S.A., Robert F. L. Self, Patrick A'Hearn, Peter A. Jumars, Darrell R. Jackson, Michael D. Richardson, Kevin B. Briggs Jan 2001

Effects Of Macrofauna On Acoustic Backscatter From The Seabed: Field Manipulations In West Sound, Orcas Island, Washington, U.S.A., Robert F. L. Self, Patrick A'Hearn, Peter A. Jumars, Darrell R. Jackson, Michael D. Richardson, Kevin B. Briggs

Journal of Marine Research

Previous observations with a bottom-mounted, radially scanning sonar (BAMS) at 40 kHz suggested that macrofaunal activities influence low-angle, acoustic backscatter from seafloor sediments. In order to test that possibility experimentally, we measured and modeled time series of backscatter strength at both 40 and 300 kHz prior to manipulation and then introduced several macrofaunal species at known abundances to randomly selected locations within the ensonified area. We worked in West Sound, Orcas Island, Washington, at a water depth of 20.4 m and for the more frequently recorded 40-kHz series extracted effects by the time-series method known as "intervention analysis," wherein the …

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Enhancing Medical Observational Skills Through Fine Art : A Randomized Controlled Study, Jacqueline Dolev Jan 2001

Enhancing Medical Observational Skills Through Fine Art : A Randomized Controlled Study, Jacqueline Dolev

Yale Medicine Thesis Digital Library

No abstract provided.

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