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Drifters In The Gulf Stream, G. G. Mcgrath, T. Rossby, J. T. Merrill

Journal of Marine Research

In the past, the Gulf Stream has frequently been viewed as essentially a barrier between the Slope and Sargasso seas. On the other hand, surface drifters have often been observed to leave the stream to the south. To gain a better understanding of surface flow of the Gulf Stream, we used drifter trajectory data to study their drift east and patterns of loss from the current. Two sets of drifter data were used, one from the 1995–1999 Georges Bank GLOBEC program and the other from the Global Drifter Program. We also made use of atmospheric wind stress estimates from a …

From Centennial To Millennial Oscillation Of The Thermohaline Circulation, Florian Sévellec, Thierry Huck, Alain Colin De Verdière

Journal of Marine Research

The freshwater flux intensity is used as the main control parameter to destabilize the ThermoHaline Circulation (THC): as it increases, the classical bifurcation scenario, thermal stable steady state, millennial oscillation and haline stable steady state are reproduced in a 2D zonally-averaged ocean model under mixed boundary conditions. Both bifurcations arise through global bifurcations leading to an infinite period of the limit cycle. Here we highlight a centennial oscillation important for the instability of the thermal phase of the millennial oscillation and which could be considered as a precursor to the collapse of the THC. It is suggested that the existence …

Habitat-Related Benthic Macrofaunal Assemblages Of Bays And Estuaries Of The Western United States, J. Ananda Ranasinghe, Kathy I. Welch, Peter N. Slattery, David E. Montagne, David D. Huff, Henry Lee Ii, Jeffrey L. Hyland, Bruce Thompson, Stephen B. Weisberg, James M. Oakden, Donald B. Caiden, Ronald G. Velarde

United States Environmental Protection Agency: Publications

Data from 7 coastwide and regional benthic surveys were combined and used to assess the number and distribution of estuarine benthic macrofaunal assemblages of the western United States. Q-mode cluster analysis was applied to 714 samples and site groupings were tested for differences in 4 habitat factors (latitude, salinity, sediment grain size, and depth). Eight macrofaunal assemblages, structured primarily by latitude, salinity, and sediment grain size, were identified: (A) Puget Sound fine sediment, (B) Puget Sound coarse sediment, (C) southern California marine bays, (D) polyhaline central San Francisco Bay, (E) shallow estuaries and wetlands, (F) saline very coarse sediment, (G) …

Water-Mass Transformation In The Shelf Seas, Gualtiero Badin, Richard G. Williams, Jonathan Sharples

Journal of Marine Research

The rate at which water masses are transformed from one density class to another is assessed in the shelf seas using the Walin (1982) framework. For a tidal-mixing front, the transformation is estimated using air-sea density fluxes and the diapycnal mixing diagnosed from a series of one-dimensional mixed layer models running across the shelf. These transformation rates diagnosed from the air-sea fluxes and diapycnal mixing agree with volume changes diagnosed directly from the model. The transformation from air-sea fluxes reaches a maximum amplitude typically twice that provided by diffusive mixing. This framework is extended to estimate the rate at which …

Depth-Integrated Steric Height As A Tool For Detecting Non-Sverdrup Behavior In The Global Ocean, J. Stuart Godfrey, Jeff R. Dunn

Journal of Marine Research

Godfrey's (1989) (referred to below as G89) calculation of the global field of annual mean Depth-Integrated Steric Height, or Sverdrup et al.'s (1942) "Transport Function," (Q) is revisited, using newer products for wind stresses, temperature and salinity. Observed Q and its wind-estimated equivalent Q_W are compared more extensively along eastern oceanic boundaries than in G89. Q and Q_W are also compared along the inner edge of the Pacific western boundary, at locations where G89 theory suggests that such a comparison is possible. A similar comparison along the western Atlantic improves after a 16 Sv correction …

The Effect Of Iron- And Light-Limitation On Phytoplankton Communities Of Deep Chlorophyll Maxima Of The Western Pacific Ocean, Zackary I. Johnson, Ragini Shyam, Anna E. Ritchie, Cecile Mioni, Veronica P. Lance, James W. Murray, Erik R. Zinser

Journal of Marine Research

The deep chlorophyll maximum (DCM) is a widespread feature in most stratified, oligotrophic waters. In addition to their well-established importance for many surface phytoplankton communities, more recent evidence suggests that iron, light or co-limitation may also be important drivers for some DCM communities. To test this hypothesis, we describe the results from six grow-out experiments, four from the Equatorial Pacific Ocean (between 150°E and 140°W), one in Western Pacific Warm Pool (9°S, 170°E) and one in the middle of the Tasman Sea (36°S). Photosynthetic efficiency (Fv/Fm) and biomass response, including Chl a and phytoplankton community structure (pennate diatoms, photosynthetic eukaryotes, …

Moored Observations Of Bottom-Intensified Motions In The Deep Canada Basin, Arctic Ocean, M.-L. Timmermans, L. Rainville, L. Thomas, A. Proshutinsky

Journal of Marine Research

In the deep Canada Basin, below the sill depth (about 2400 m) of the Alpha-Mendeleyev Ridge, potential temperature and salinity first increase with depth, then remain uniform from about 2600 m to the bottom (approximately 3500 m). Year-long moored measurements of temperature, salinity and pressure in these deep and homogeneous bottom waters reveal significant vertical excursions with periods of about 50 days. The observed isopycnal displacements have amplitudes up to 100 m at the top boundary of the bottom layer; moored profiler measurements in the intermediate water column indicate that the amplitudes of these vertical displacements decay toward the surface …

Sea Ice Melt And Meteoric Water Distributions In Nares Strait, Baffin Bay, And The Canadian Arctic Archipelago, Matthew B. Alkire, Kelly K. Falkner, Timothy Boyd, Robie W. Macdonald

Journal of Marine Research

Sea ice melt (SIM), meteoric water (river runoff net precipitation), and Pacific seawater contributions to the upper waters of the Canadian Arctic Archipelago (CAA), Nares Strait, and Baffin Bay during late summer 1997 and 2003 are estimated from salinity, δ¹⁸O, and nutrient data. Salinity-δ¹⁸O relationships within the study area suggest that the CAA inherits a net sea-ice formation (brine) signal from the Arctic Ocean. Inherited brine complicates the estimation of local contributions from sea ice melt and glacial runoff, especially where a significant component of the surface water derives from Arctic outflow. Our data are characterized …

Investigation Of The Physicochemical Features And Mixing Of East/Japan Sea Intermediate Water: An Isopycnic Analysis Approach, Il-Nam Kim, Dong-Ha Min, Dae Hyun Kim, Tongsup Lee

Journal of Marine Research

We present spatial distributions of the mixing ratio and properties of the East/Japan Sea Intermediate Water (ESIW) at its core density layer (σ_θ = 27.2–27.3) based on high-quality hydrographic data observed in the East/Japan Sea (EJS) during summer 1999. ESIW is defined as a source water type showing minimum salinity and maximum dissolved oxygen concentration. ESIW plays an important role in supplying dissolved oxygen and transporting anthropogenic carbon into the intermediate/deep layers in EJS. Studying the ESIW formation and distribution processes may provide insights on EJS's shallow- to mid-depth thermohaline circulation and recent ocean changes. Here, we combine the …

Predator-Prey Interaction In Estuarine Bivalves: Size Selection, Effects Of Salinity, And Indirect Interactions, Barry Richard Aronhime

LSU Doctoral Dissertations

High stress environments can reduce species diversity. How such stress-induced reduction in predator diversity impacts prey survival is less well studied. Brackish waters in estuaries are stressful, species depauperate areas, but also prime oyster habitat in Louisiana. Surveys revealed reduced bivalve predator diversity at the low salinity (high stress) site. Exclosure experiments indicated highest prey mortality at the high salinity (low stress) site. Predator enclosures corroborated the field study results, with reduced consumption rates at the low salinity site for both stone crabs, Menippe adina and oyster drills Stramonita haemastoma, but not blue crabs, Callinectes sapidus. Blue crab mortality in …

Measuring Lateral Heat Flux Across A Thermohaline Front: A Model And Observational Test, Barry R. Ruddick, Neil S. Oakey, Dave Hebert

Journal of Marine Research

We develop and test a method to observationally estimate lateral intrusive heat flux across a front. The model combines that of Joyce (1977), in which lateral cross-frontal advection by intrusions creates vertical temperature gradients, and Osborn and Cox (1972) in which vertical mixing of those gradients creates thermal microstructure that is dissipated by molecular conduction of heat. Observations of thermal microstructure dissipation χ_T are then used to estimate the production by intrusions, and hence the lateral heat flux and diffusivity. This method does not depend on the precise mechanism(s) of mixing, or on the dynamical mechanisms driving the frontal …

Towards The Development Of A Coastal Prediction System For The Tampa Bay Estuary, Heather Holm Havens

USF Tampa Graduate Theses and Dissertations

The objective of this research is to evaluate a coastal prediction system under various real world scenarios to test the efficacy of the system as a management tool in Tampa Bay. The prediction system, comprised of a three-dimensional numerical circulation model and a Lagrangian based particle tracking model, simulates oceanographic scenarios in the bay for past (hindcast), present (nowcast) and future (forecast) time frames. Instantaneous velocity output from the numerical circulation model drives the movement of particles, each representing a fraction of the total material, within the model grid cells.

This work introduces a probability calculation that allows for rapid …

Spatiotemporal Estuarine Water Quality Parameterization Using Remote Sensing And In-Situ Characteristics, Kwisun Park Yu

Civil & Environmental Engineering Theses & Dissertations

This dissertation develops a new paradigm in a water quality monitoring approach to parameterize spatiotemporal estuarine water quality with sustainable reliability, less cost and less time. A key underpinning of this paradigm of the spatiotemporal estuarine water quality parameterization is various water quality parameters' interrelationship with ambient water temperature as a common factor, their time dependent characteristics, and spatiotemporal characteristics of remote sensing. It has two core models to provide input data of water quality parameterization model in a system; the transfer function models of the physical system and an analytical temperature time series model. The objective of this dissertation …

Spatial Interactions In The Macoma Balthica Community Control Biogeochemical Fluxes At The Sediment-Water Interface And Microbial Abundances, Emma Michaud, Gaston Desrosiers, Robert C. Aller, Florian Mermillod-Blondin, Bjorn Sundby, Georges Stora

Journal of Marine Research

We examined how interactions among the three dominant species of the Macoma balthica community in the St-Lawrence estuary influence net biogeochemical fluxes and the composition of the sedimentary bacterial community. We manipulated the biodiversity of the community via combinations of Macoma balthica, Mya arenaria, and Nereis virens in sediment microcosms containing sieved and homogenized tidal-flat sediment. Each combination was adjusted to similar total biovolumes and in situ animal densities. Compared to treatments with single species, which were also adjusted to similar biovolumes and densities, combinations of multiple species changed the fluxes of oxygen, phosphate, ammonium, and nitrate across the sediment-water …

Henry Sears (1913–1982), George Veronis

Journal of Marine Research

Henry Sears led a remarkably varied life centered on a love of sailing, racing and fishing. Even as a youngster he spent considerable time at sea because he had asthma and in those days sea air was considered beneficial for one with that ailment. He owned a Swampscott Dory at the age of eight and soon afterwards was sailing a 30-footer from Boston to the Maine coast. His education was unusual. It seems that he was dyslexic, although at the time of his birth dyslexia was not identified as such. During his childhood his family spent three months of the …

Floral Patterns In The California Current: The Coastal-Offshore Boundary Zone, E. L. Venrick

Journal of Marine Research

This study quantified the vertical distributions of 294 taxa of phytoplankton from 112 samples in a vertical section across the California Current system off Southern California. The goal was to examine the relationship between coastal and offshore floras throughout the euphotic zone. The two associations were distinct throughout the upper 140 m. The coastal flora was found in water adjacent to and east of the Santa Rosa Ridge. The offshore flora occurred west of the California Current, and also at the station immediately east of the current, presumably the result of upstream entrainment across it. Both coastal and offshore floras …

Rossby Wave Radiation From An Eastward Jet And Its Recirculations, Genta Mizuta

Journal of Marine Research

A series of numerical experiments is carried out to investigate in detail the properties of the variability radiated from a baroclinic jet and its recirculations. Driven by an inflow from the western boundary, an eastward jet and two recirculation gyres are formed in the statistically steady state. The variability of velocity away from the recirculation gyres is as strong as that near the jet at deeper depths, and the structure of this velocity variability was analysed by using the technique of Frequency-Domain Empirical Orthogonal Functions (FDEOFs). Motions represented by the first FDEOFs consist of the barotropic Rossby waves of various …

Dynamics Of The Indonesian Seas Circulation. Part Ii – The Role Of Pressure Head, Vladimir M. Kamenkovich, Kieran T. A. O'Driscoll, Dmitri A. Nechaev

Journal of Marine Research

The aim of this paper is to analyze the role of the pressure head, i.e., the difference of total pressure forces acting on the Indonesian seas waters from the western Pacific and the eastern Indian Ocean, in driving the Indonesian Throughflow (ITF) and in determining the total transport of the ITF. These questions have been discussed in the literature but no consensus has been reached. A regional model of the Indonesian seas circulation has been developed that properly resolves all major topographic features in the region. The results of model runs have been used to calculate all components of the …

Winter Advection Of Iron Can Explain The Summer Phytoplankton Bloom That Extends 1000 Km Downstream Of The Kerguelen Plateau In The Southern Ocean, M. M. Mongin, E. R. Abraham, T. W. Trull

Journal of Marine Research

The predominantly low-chlorophyll conditions of the Southern Ocean are punctuated by regions of elevated phytoplankton biomass, including a bloom in the Antarctic Circumpolar Current (ACC) that extends for 1000 km downstream of the Kerguelen-Heard islands. Summer-time studies have demonstrated that iron from the islands and intervening shallow plateau (300–600 m) fuels localized production. Whether this supply, or alternatively iron brought to the surface by enhanced mixing in ACC eddies, drives the more extensive downstream bloom has not been addressed. We show that the extent and shape of the downstream bloom can be reproduced by simulating the winter-time spread of a …

Deep Cyclogenesis By Synoptic Eddies Interacting With A Seamount, Andrew D. Greene, Georgi G. Sutyrin, D. Randolph Watts

Journal of Marine Research

Strong deep eddies with cyclonic vorticity greater than 0.2 f₀ were detected using an array of bottom current and pressure measurements in the Kuroshio Extension System Study (KESS) in 2004–2006. Daily maps showed these deep eddies developed locally. As in the Gulf Stream, meandering of the upper baroclinic jet generates deep cyclones and anticyclones by stretching and squashing the lower water column. However, unlike the Gulf Stream, the smaller vertical stretching and greater water depth in the Kuroshio Extension limits the relative vorticity generated by this vertical coupling process to about 0.1 f₀. In the deep Kuroshio …

Intermittent Layering In The Atlantic Equatorial Deep Jets, Claire Ménesguen, Bach Lien Hua, Mark D. Fruman, Richard Schopp

Journal of Marine Research

Equatorial observations in the Atlantic show three distinct vertical scales: quasi-barotropic eastward Extra-Equatorial Jets (EEJ), Equatorial Deep Jets (EDJ) of scale 500–800 m, and a smaller scale signal (50–100 m) of thin layers of well-mixed tracer fields. In the combined system of jets, westward EDJ correspond to zero-Potential Vorticity (PV) "niches," inside of which most of the thin well-mixed layers are found. Because of its correlation with zero-PV niches, the formation of layers is interpreted as due to inertial instability. The latter encompasses inertial barotropic instability due to meridional shear (either steady or parametric), baroclinic symmetric instability due to sloping …

Dynamics Of The Combined Extra-Equatorial And Equatorial Deep Jets In The Atlantic, Claire Ménesguen, Bach Lien Hua, Mark D. Fruman, Richard Schopp

Journal of Marine Research

The available meridional sections of zonal velocity with high vertical and meridional resolution reveal tall eastward jets at 2N and 2S, named the extra-equatorial jets (EEJ), straddling the stacked eastward and westward jets of smaller vertical scales right at the equator, the so-called equatorial deep jets (EDJ). In contrast to the semi-annual to interannual fluctuations in the zonal velocity component, the measured meridional velocity component is dominated by intraseasonal period. We argue here that the formation mechanism for both types of jets is linked to the intraseasonal variability in meridional velocity and the associated wave motions. A process study is …

Deep Chlorophyll Maximum And Upper Ocean Structure Interactions: Case Of The Guinea Thermal Dome, Olaf Duteil, Alban Lazar, Yves Dandonneau, Ilana Wainer, Christophe Menkes

Journal of Marine Research

Deep Chlorophyll Maximum (DCM) modifies the upper ocean heat capture distribution and thus impacts water column temperature and stratification, as well as biogeochemical processes. This energetical role of the DCM is assessed using a 1 m-resolution 1D physical-biogeochemical model of the upper ocean, using climatological forcing conditions of the Guinea Dome (GD). This zone has been chosen among others because a strong and shallow DCM is present all year round. The results show that the DCM warms the seasonal thermocline by +2°C in September/October and causes an increase of heat transfer from below into the mixed layer (ML) by vertical …

Perturbation Dynamics Of A Planktonic Ecosystem, Katherine Healey, Adam H. Monahan, Debby Ianson

Journal of Marine Research

Planktonic ecosystems provide a key mechanism for the transfer of carbon from the atmosphere to the deep ocean via the so-called "biological pump." Mathematical models of these ecosystems have been used to predict CO₂ uptake in surface waters at particular locations, and more recently have been embedded in global climate models. While the equilibrium properties of these models are well studied, less attention has been paid to their response to external perturbations, despite the fact that as a result of the variability of environmental forcing such ecosystems are rarely, if ever, in equilibrium. In this study, linear theory is …

The Future Evolution Of The Southern Ocean Co2 Sink, Nicole S. Lovenduski, Takamitsu Ito

Journal of Marine Research

We investigate the impact of century-scale climate changes on the Southern Ocean CO₂ sink using an idealized ocean general circulation and biogeochemical model. The simulations are executed under both constant and changing wind stress, freshwater fluxes, and atmospheric pCO₂, so as to separately analyze changes in natural and anthropogenic CO₂ fluxes under increasing wind stress and stratification. We find that the Southern Ocean sink for total contemporary CO₂ is weaker under increased wind stress and stratification by 2100, relative to a control run with no change in physical forcing, although the results are sensitive …

Evidence Of Infaunal Effects On Porewater Advection And Biogeochemistry In Permeable Sediments: A Proposed Infaunal Functional Group Framework, George G. Waldbusser, Roberta L. Marinelli

Journal of Marine Research

Bioturbating infauna significantly modify reaction and transport processes in permeable sediments, though most studies to date are limited in the scope of species examined. We conducted a comparative field study measuring density-dependent effects of six common bioturbating species on porewater advection and biogeochemistry, across three intertidal permeable sediment habitats. The species in this study are; head-down like deposit feeders (Abarenicola pacifica and Balanoglossus aurantiacus), surface deposit feeders (Diopatra cuprea and Onuphis jenneri) and gallery diffusers (Upogebia pugettensis and Neotrypaea californiensis). Tracer loss from gel diffusers was used to assess relative differences in porewater advection …

The Skirted Island: The Effect Of Topography On The Flow Around Planetary Scale Islands, Joseph Pedlosky, Roberto Iacono, Ernesto Napolitano, Karl Helfrich

Journal of Marine Research

The flow around planetary scale islands is examined when the island possesses a topographic skirt representing a steep continental shelf. The model is barotropic and governed by the shallow water equations and the motion is driven by a wind stress with a constant curl. The presence of the strong topographic "skirt" around the island vitiates the elegant Island Rule of Godfrey and the closed potential vorticity contours around the island produced by the topography allow a geostrophic, stationary mode to resonate with an amplitude that is limited only by dissipation. In the limit of weak forcing the outline of the …

Asymmetries In Tidal Flow Over A Seto Inland Sea Scour Pit, Arnoldo Valle-Levinson, Xinyu Guo

Journal of Marine Research

Underway profiles of current velocity were combined with stationary profiles of temperature and salinity around a vertically mixed scour pit of the Seto Inland Sea throughout a semidiurnal tidal cycle. This was done with the purpose of determining (a) whether flood flow is asymmetric relative to ebb over a pit with weakly stratified conditions, and (b) whether there is a dynamic transition from frictionally dominated tidal flow to advectively dominated tidal flow over the pit. These questions arose from previous studies elsewhere under stratified water columns, in contrast to the unstratified conditions at the study site. Observations showed an acceleration …

Plankton Community Composition, Organic Carbon And Thorium-234 Particle Size Distributions, And Particle Export In The Sargasso Sea, H. S. Brew, S. B. Moran, M. W. Lomas, A. B. Burd

Journal of Marine Research

Measurements of plankton community composition (eight planktonic groups), particle size-fractionated (10, 20, 53, 70, and 100-μm Nitex screens) distributions of organic carbon (OC) and ²³⁴Th, and particle export of OC and ²³⁴Th are reported over a seasonal cycle (2006–2007) from the Bermuda Atlantic Time-Series (BATS) site. Results indicate a convergence of the particle size distributions of OC and ²³⁴Th during the winter-spring bloom period (January–March, 2007). The observed convergence of these particle size distributions is directly correlated to the depth-integrated abundance of autotrophic pico-eukaryotes (r = 0.97, P < 0.05) and, to a lesser extent, Synechococcus (r = 0.85, P < 0.14). In addition, there are positive correlations between the sediment trap flux of OC and ²³⁴Th at 150 …

New Observations Of The Spreading And Variability Of The Antarctic Intermediate Water In The Atlantic, Claudia Schmid, Silvia L. Garzoli

Journal of Marine Research

The new and unique Argo data set currently available, in conjunction with other data previously collected, increases our understanding of the spreading of the Antarctic Intermediate Water in the southern and tropical Atlantic Ocean and to verify previous results. The combination of velocity and salinity data collected with Argo floats verified the main patterns of circulation at intermediate (800 to 1100 dbar) depths. Interesting new features in the pathways are found: (1) the existence of a new, third, branch of westward to northwestward flow that is fed by the Benguela Current; (2) two pathways through which the water from the …