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Intraseasonal Variability In The Makassar Strait Thermocline, Kandaga Pujiana, Arnold L. Gordon, Janet Sprintall, R. Dwi Susanto

Journal of Marine Research

Intraseasonal variability [ISV] in the Makassar Strait thermocline is examined through the analysis of along-channel flow, regional sea level anomaly and wind fields from January 2004 through November 2006. The dominant variability of 45–90 day in the Makassar Strait along-channel flow is horizontally and vertically coherent and exhibits vertical energy propagation. The majority of the Makassar ISV is uncoupled to the energy exerted by the local atmospheric ISV: instead the Makassar ISV is due to the combination of a remotely forced baroclinic wave radiating from Lombok Strait and deep reaching ISV originating in the Sulawesi Sea. Thermocline depth changes associated …

Temporal And Spatial Variation In Infaunal Community Structure In Physically Active Continental Shelf Sediments At A Long-Term Ecosystem Observatory (Leo-15) Off New Jersey, Usa, J. Frederick Grassle, Patricia A. Ramey, Rosemarie F. Petrecca

Journal of Marine Research

When the LEO-15 (Long-term Ecosystem Observatory at 15-m depth) research area was designated around Beach Haven Ridge (39°27.69′ N, 74°15.81′ W) in the early 1990's several stations were selected to reflect the different physical regimes and habitats present in a highly dynamic shelf environment. This study determined the composition, diversity, and abundance of infaunal communities at three contrasting stations on five dates in 1994–1995. A unique sampling scheme was used where a nested design was combined with targeted sampling by divers of benthic topographic habitat features, namely crests and troughs of sand ripples. The total number of taxa collected was …

Mixing In Cyclonic Eddies In The Antarctic Circumpolar Current, Angela Hibbert, Harry Leach, Volker Strass, Boris Cisewski

Journal of Marine Research

Observations over a period of 39 days of the increasing minimum core temperature of Winter Water trapped within a mature cyclonic eddy in the Antarctic Circumpolar Current encouraged us to assess the mixing processes which might lead to this temperature rise. Using diffusive heat budgets for alternatively diapycnic (∼vertical) and then isopycnic (∼horizontal) mixing combined with the observed rate of warming allowed upper limits for diapycnic and isopycnic diffusivities to be inferred. This gave values of (3.3 ± 0.8) × 10⁻⁴m²s⁻¹ and 87 ± 20m²s⁻¹ for the diapycnic and isopycnic diffusivities respectively. …

On The Interannual Variability Of Nitrogen Fixation In The Subtropical Gyres, Fanny M. Monteiro, Michael J. Follows

Journal of Marine Research

Time-series observations of geochemical tracers and diazotroph abundances in the northern subtropical gyres suggest variability in nitrogen fixation on interannual and longer timescales. Using a highly idealized model of the biogeochemistry and ecology of a subtropical gyre, we explore the previously proposed hypothesis that such variability is regulated by an internal "biogeochemical oscillator." We find, in certain parameter regimes, self-sustained oscillations in nitrogen fixation, community structure and biogeochemical cycles even with perfectly steady physical forcing. During the oscillations of nitrogen fixation, "blooms" of diazotrophs occur at intervals between a year and several decades, consistent with the observed variability. The period …

Dynamics Of The Indonesian Seas Circulation. Part I – The Influence Of Bottom Topography On Temperature And Salinity Distributions, Kieran T. A. O'Driscoll, Vladimir M. Kamenkovich

Journal of Marine Research

The influence of bottom topography on the distribution of temperature and salinity in the Indonesian seas region has been studied with a high-resolution model based on the Princeton Ocean Model. One of the distinctive properties of the model is an adequate reproduction of all major topographic features in the region by the model bottom relief. The three major routes of flow of Pacific water through the region have been identified. The western route follows the flow of North Pacific Water through the Sulawesi Sea, Makassar Strait, Flores Sea, and Banda Sea. This is the main branch of the Indonesian Throughflow. …

Mass Transport In The Stokes Edge Wave, Jan Erik H. Weber, Peygham Ghaffari

Journal of Marine Research

The Lagrangian mass transport in the Stokes progressive edge wave is obtained from the vertically integrated equations of momentum and mass, correct to second order in wave steepness. The cross-shore momentum balance is between the mean pressure at the sloping bottom, the radiation stress, and the pressure gradient due to the mean surface slope. In the alongshore direction, the effect of viscosity leads to a wave attenuation, and hence a radiation stress component. The frictional effect on the mean Eulerian motion is modeled through a turbulent bottom drag. The alongshore momentum balance is between the mean pressure gradient due to …

A Linear Diffusivity Model Of Near-Surface, Cross-Shore Particle Dispersion From A Numerical Simulation Of Central California’S Coastal Ocean, Patrick T. Drake, Christopher A. Edwards

Journal of Marine Research

A simple diffusion model of cross-shore mixing employing an inhomogeneous diffusivity is applied to near-surface particle dispersion within a high-resolution numerical model of the central California coastal ocean. The theoretical model employs a linear diffusivity, K_y = νy, where y is the cross-shore coordinate and ν a constant, as traditionally assumed for wall-layer flows. A realistic implementation of the Regional Ocean Modeling System (ROMS) is used to generate hundreds of thousands of three-dimensional, passive particle trajectories. Particles were released daily along the inner shelf for one model year, 2002, tracked for 16 days and treated statistically as …

Irminger Current Anticyclones In The Labrador Sea Observed In The Hydrographic Record, 1990 –2004, Tatiana Rykova, Fiammetta Straneo, Jonathan M. Lilly, Igor Yashayaev

Journal of Marine Research

A significant fraction of the lateral heat transport into the Labrador Sea's interior, needed to balance the net heat loss to the atmosphere, is attributed to the Irminger Current Anticyclones. These mesoscale eddies advect warm, salty boundary current water, of subtropical origin, from the boundary current to the interior— but when or how they release their anomalous heat content has not been previously investigated. In this study, we discuss the seasonal and interannual evolution of these anticyclones as inferred from the analysis of hydrographic data from the Labrador Sea from 1990 to 2004. The 29 identified anticyclones fall into two …

Relative Dispersion In The Nordic Seas, I. Koszalka, J. H. Lacasce, K. A. Orvik

Journal of Marine Research

We examine the relative dispersion of surface drifters deployed in the POLEWARD experiment in the Nordic Seas during 2007–2008. The drifters were launched in pairs and triplets, yielding 67 pairs with an initial separation of 2 km or less. There were 26 additional pairs from drifters which subsequently came near one another. As these produced statistically identical dispersion to the original pairs, we used them as well, yielding 93 pairs. The relative dispersion exhibits three phases. The first occurs during the first two days, at spatial scales less than 10 km. The dispersion increases approximately exponentially during this period, with …

Effects Of Surface Forcing On The Seasonal Cycle Of The Eastern Equatorial Pacific, D. E. Harrison, A. M. Chiodi, G. A. Vecchi

Journal of Marine Research

The roles of zonal and meridional wind stress and of surface heat flux in the seasonal cycle of sea surface temperature (SST) are examined with a primitive equation (PE) model of the tropical Pacific Ocean. While a variety of previous numerical and observational studies have examined the seasonal cycle of SST in the eastern tropical Pacific, it is noteworthy that different mechanisms have been invoked as primary in each case and different conclusions have been reached regarding the relative importance of the various components of surface forcing. Here, we perform a series of numerical experiments in which different components of …

Salt Flux Into Coastal River Plumes: Dye Studies In The Delaware And Hudson River Outflows, R. W. Houghton, R. J. Chant, Ana Rice, Charles Tilburg

Journal of Marine Research

The results of ten dye tracer experiments conducted in 2003–2006 to study the dispersion of the outflow of the Delaware and Hudson Rivers are presented. A fluorescent dye tracer was used to track the river plume and to measure directly the salt flux into the plume. A variety of flow regimes were encountered. During strong upwelling events, a salt flux of ∼3 ÷ 10^–4 kg m s^–1 at the leading edge of the plume implies a vertical diffusivity of K_z ∼ 3 × 10^–4 m^–2 s^–1. Comparable salt flux was measured at the …

Measuring Turbulent Large-Eddy Structures With An Adcp. Part 2. Horizontal Velocity Variance, A. E. Gargett, A. E. Tejada-Martínez, C. E. Grosch

Journal of Marine Research

This paper considers the degree of accuracy with which observations from an acoustic Doppler current profiler (ADCP) can determine turbulent horizontal velocity variance. As in a previous paper addressing turbulent vertical velocity variance, we use a combination of techniques, deriving response functions from simple theory and from oceanic observations taken with a VADCP (an ADCP with an additional vertical (V) beam) in two different oceanic turbulent flows, Langmuir supercells (LSC) and unstable convection. In the case of LSC, we also determine response by sampling available Large-Eddy Simulations (LES) with specified beam geometry. In contrast with the previous investigation, where a …

Sensitivity Of Plankton Biomass And Productivity To Variations In Physical Forcing And Biological Parameters In Chesapeake Bay, Ming Li, Liejun Zhong, Lawrence W. Harding Jr.

Journal of Marine Research

A coupled three-dimensional hydrodynamic-biogeochemical model is used to simulate plankton dynamics in Chesapeake Bay and examine its sensitivity to variations in biological parameters and physical forcing. The coupled biophysical model captures observed seasonal cycle and regional distributions of plankton in Chesapeake Bay and predicts the "phase lag" between the spring chlorophyll maximum and the summer primary productivity maximum. This lag traces to the delivery of dissolved inorganic nutrients in the winter-spring freshet from the Susquehanna River that fuels the spring bloom, whereas regenerated nutrients support high primary productivity in summer. The model shows that episodic wind events commonly associated with …

A Shallow Water Model Conserving Energy And Potential Enstrophy In The Presence Of Boundaries, Rick Salmon

Journal of Marine Research

We extend a previously developed method for constructing shallow water models that conserve energy and potential enstrophy to the case of flow bounded by rigid walls. This allows the method to be applied to ocean models. Our procedure splits the dynamics into a set of prognostic equations for variables (vorticity, divergence, and depth) chosen for their relation to the Casimir invariants of mass, circulation and potential enstrophy, and a set of diagnostic equations for variables that are the functional derivatives of the Hamiltonian with respect to the chosen prognostic variables. The form of the energy determines the form of the …

Export Of Terrestrial Dissolved Organic Matter Along A River To Ocean Transect Of The Lower Chesapeake Bay Investigated By Advanced Analytical Techniques, Rachel Leigh Sleighter

Chemistry & Biochemistry Theses & Dissertations

Ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) has proved essential for the complete separation of the thousands of peaks present in natural organic matter (NOM), a complex assemblage of organic molecules present in water, soils, and sediments. An improved understanding of its composition is crucial to understand how pollutants interact with NOM and how NOM cycles through global carbon cycles.

Optimizing the acquisition and handling of the FTICR mass spectra is the first step to obtaining high quality data. A simple method to internally calibrate the peaks in the complex spectra, using naturally present fatty …

Identification Of A Cusp Catastrophe In A Gap-Leaping Western Boundary Current, Joseph J. Kuehl, Vitalii A. Sheremet

Journal of Marine Research

The Luzon Strait is an example of a location where a western boundary current must negotiate a gap in bathymetry. In the gap region, the current can exhibit multiple steady states (leaping the gap or penetrating the gap) and hysteresis (dependence on past flow state). Laboratory experiments on such flows are presented in order to investigate the system behavior in a two-dimensional parameter space of varying flow rate and platform rotation rate. The experiments were performed in a cylindrical tank on a one-meter rotating table. A semi-circular ridge with a gap was inserted over sloping bottom topography in the active …

Mechanisms Of Variability In A Convective Basin, Julie Deshayes, Fiammetta Straneo, Michael A. Spall

Journal of Marine Research

An idealized model for a convective basin is used to investigate the mechanisms of variability of the formation and export of dense water. In this model, which consists of two isopycnic layers, dense water formation is induced by surface buoyancy loss in the interior, which is at rest. Newly formed dense water is transmitted to the surrounding boundary current through parameterized eddy fluxes. Variability in the formation and export of dense water is due to changes in the two main drivers: variations in the surface buoyancy fluxes and variations in the large-scale wind via a barotropic boundary current. Numerical integrations …

The Variability Of Currents And Sea Level In The Upper Delaware Estuary, Kuo-Chuin Wong, Christopher K. Sommerfield

Journal of Marine Research

The variability of currents and sea levels in the upper Delaware estuary are examined based on measurements from bottom mounted acoustic Doppler current profilers (ADCP) deployed at two sites (New Castle and Tinicum) from 18 March to 10 June 2003. New Castle is located 104 km from the mouth, and Tinicum is located another 32 km up-estuary. Supplemental data, including sea level at the mouth of the estuary, river discharge, and wind speed and direction, were also obtained from various federal agencies. The instantaneous current represents a superposition of variability driven by the tide, wind, and river discharge. Over the …

Isentropic Averaging, Roland A. De Szoeke

Journal of Marine Research

The equations of motion, thermodynamics and scalar concentration are averaged separately over infra-grid scales (comprising roughly ocean microstructure scales) and sub-grid scales (encompassing 10–100 km scales), the latter average being carried out on constant potential temperature surfaces. (Since variation of salinity has been neglected, potential temperature is synonymous with entropy.) These methods of averaging are used to lend precision to statements about oceanic turbulent diffusion: that infra-grid scales are primarily responsible for dientropic diffusion; and that sub-grid scales are responsible for along-isentropic diffusion of passive scalars. Equivalent sets of averaged equations expressed either in isentropic coordinates or quasi-Cartesian coordinates can …

Integrated Responses Of Crustaceans Inhabiting Estuaries To The Challenges Of Feeding And Digestion In Low Salinity, Daniel Luke Curtis

UNLV Theses, Dissertations, Professional Papers, and Capstones

Estuaries are highly productive and serve as vital habitats for numerous decapod crustacean species. However, the environmental conditions within estuaries are often highly dynamic and subject to large changes in salinity and temperature that occur on seasonal and tidal scales. Not all of the species occupying these habitats are adept in coping with changes in these environmental conditions. This dissertation describes the influence of low salinity conditions on the 1) habitat preference, 2) feeding behaviour and 3) digestive physiology of crustaceans inhabiting estuaries. I have primarily focussed on a weak osmoregulator, the Dungeness crab, Cancer magister , but have also …

Critical Turbulence Revisited: The Impact Of Submesoscale Vertical Mixing On Plankton Patchiness, A. W. Omta, S. A. L. M. Kooijman, H. A. Dijkstra

Journal of Marine Research

By supplying nutrients to the ocean surface, submesoscale vertical motions can have a strong impact on phytoplankton growth and phytoplankton distributions. To study this impact, we model a phytoplankton population in a baroclinically unstable submesoscale eddy using a phytoplankton model coupled to a three-dimensional hydrodynamic model. In the eddy, strong vertical transports are generated as a consequence of baroclinic instability. The resulting plankton distributions turn out to depend strongly on the light intensity and local vertical transport. To analyze these distributions in detail, we use more idealized coupled hydrodynamic-biological models and we extend the critical turbulence concept to three dimensions.

Death Of Three Loop Current Rings, B. L. Lipphardt Jr., A. C. Poje, A. D. Kirwan Jr., L. Kantha, M. Zweng

Journal of Marine Research

The life cycle of large anticyclonic rings in the Gulf of Mexico (GOM) is widely described by pinch off from the Loop Current, migration across the Gulf and eventual spin down along the western slope. Extensive observational and modeling efforts provide a relatively consistent picture of rings pinching off from the Loop Current and of complex interaction between anticyclones and cyclones driven by bathymetry along the western and northwestern shelf. The observational record for Loop Current rings (LCRs) during the intermediate period of westward translation is less clear. A number of studies recognize distinct anomalies in LCR characteristics in deep …

Porewater Advection By Hydraulic Activities Of Lugworms, Arenicola Marina: A Field, Laboratory And Modeling Study, David S. Wethey, Sarah A. Woodin, Nils Volkenborn, Karsten Reise

Journal of Marine Research

Porewater pressure gradients generated by activities of the lugworm Arenicola marina were measured in the laboratory and in unrestrained field situations to determine the spatial extent of influence of individuals on porewater advection. These subsurface deposit-feeders live head-down in sediments in J-shaped burrows and defecate on the surface. Individual animals generated pressures of up to 18 cm H₂O in the region of the feeding pocket, and the pressures decayed radially from the source with an exponent of -1.3. Pressure transients from defecation are detectable 50 cm from the source in unrestrained field populations. The porewater flows resulting from …

Hydrography And Flow In The Lucky Strike Segment Of The Mid-Atlantic Ridge, A. M. Thurnherr, G. Reverdin, P. Bouruet-Aubertot, L. C. St. Laurent, A. Vangriesheim, V. Ballu

Journal of Marine Research

The Lucky Strike segment between 37 and 38N on the Mid-Atlantic Ridge is the focus of the international MoMAR program to monitor seafloor-spreading processes. During the GRAVILUCK cruise in August 2006, hydrographic, velocity and light-scattering data were collected in the rift valley at Lucky Strike in order to investigate the regional dynamics and to provide background information for the monitoring effort. The survey observations reveal a remarkably simple dynamical setting dominated by persistent northward flow transporting ≈0.2 Sv of water along the rift valley. Approximately half of this transport must upwell within a deep basin that occupies the northern half …

Larval Settlement In Flocculated Particulates, Cheryl Ann Zimmer, Victoria R. Starczak, Victoria C. Arch, Richard K. Zimmer

Journal of Marine Research

Planktonic larval settlement can be a major determinant of population and community dynamics. Settlement templates of benthic invertebrates have been attributed to biological, chemical, and hydrodynamic mechanisms. Completely unexplored, however, is the role of patchy, but widespread, flocculated particulates (“floc”) that intermittently rest on substrate surfaces. Motivated by observations of very high (of order 10⁶ m^-3) larval/postlarval densities in floc from a coastal embayment, this study experimentally identified physical and behavioral mechanisms responsible for these associations. In annular-flume studies, sediment cores were mounted flush with the channel bottom, serving as the floc source. Larval (Capitella sp. …

Modeling Effects Of Patchiness And Biological Variability On Transport Rates Within Bioturbated Sediments, Sebastien Delmotte, Magali Gerino, Jean Marc Thebault, Filip J. R. Meysman

Journal of Marine Research

Bioturbation models are typically one-dimensional, with the underlying assumption that tracer gradients are predominantly vertical, and that sediment reworking is laterally homogeneous. These models implicitly assume that bioturbation activity does not vary with horizontal location on the sediment surface. Benthic organisms, however, are often patchily distributed. Moreover, due to natural variability, bioturbation activity varies among individuals within a population, and hence, among bioturbated patches. Here we analyze a 1D model formulation that explicitly includes patchiness, exemplified by conveyor-belt transport. The patchiness is represented with one coefficient α_b, as the fraction of bioturbated areas of the total area. First, …

Interannual Variability In The Seasonal Cycle Of Chlorophyll In The Leeuwin Current Off The Southwest Western Australian Coast, Jim E. Greenwood, Karline Soetaert

Journal of Marine Research

The seasonal cycle of surface chlorophyll in the Leeuwin Current off the southwest Western Australian coast is characterized by low austral summer concentrations that increase during the austral autumn and winter. Results from a one-dimensional numerical model show that a combination of solar heating and nutrient poor surface waters during the summer can restrict plankton growth to the base of the euphotic zone resulting in low surface chlorophyll concentrations that are consistent with observations. The model also suggests that increased vertical mixing caused by surface cooling can explain some of the observed increases in surface chlorophyll that occur during the …

Continuously Stratified Nonlinear Low-Mode Internal Tides, Karl R. Helfrich

Journal of Marine Research

A model for hydrostatic, fully nonlinear, low-mode internal tides is extended to continuously stratified conditions. Periodic inertia-gravity solutions of permanent form are shown to exist only for a limited range of amplitudes for a given stratification and frequency. As found in an earlier two-layer model, the solutions fall into two classes. In one, the waves take on a corner-shape as the limiting amplitude is approached. In the other, the waves remain continuous at the limiting amplitude, but have a lobate shape. Numerical investigation using the Euler equations shows that both classes of nonlinear solutions are robust to weak nonhydrostatic effects …

An Estimate Of Lagrangian Eddy Statistics And Diffusion In The Mixed Layer Of The Southern Ocean, J. B. Sallée, Kevin Speer, R. Morrow, R. Lumpkin

Journal of Marine Research

A statistical analysis of surface drifter observations is used to compute eddy length and time scales and eddy diffusion in the Southern Ocean. Eddy diffusion values of the order of 10⁴ m² s^–1 are found in the energetic western boundary currents north of the Antarctic Circumpolar Current (ACC) and secondary peaks occur where the ACC negotiates topography. The diffusivity shows an increase from the Antarctic continent to the core of the ACC, then a slight decrease or a stable plateau within the ACC. North of the ACC, diffusivity generally decreases into the interior of ocean basins, except …

Shallow Marine Carbonate Dissolution And Early Diagenesis—Implications From An Incubation Study, Xinping Hu, David J. Burdige

Journal of Marine Research

Surface carbonate sediments from sites on the Bahamas Bank with different seagrass densities were incubated across a range of O₂ delivery rates, to study the controls on metabolic carbonate dissolution in these sediments. The results confirmed the 1:1 ratio between the rates of O₂ consumption and carbonate dissolution, demonstrating that microbial respiration was the rate-limiting step in metabolic carbonate dissolution. Furthermore, the dissolution we observed was actually net dissolution resulting from coupled dissolution and reprecipitation. This carbonate reprecipitation occurs on the time scale of days, and significantly alters the pore water dissolved inorganic carbon (DIC) stable isotopic composition. …