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Cross-Shelf Structure Of Coastal Upwelling: A Two —Dimensional Extension Of Ekman’S Theory And A Mechanism For Inner Shelf Upwelling Shut Down, Philippe Estrade, Patrick Marchesiello, Alain Colin De Verdière, Claude Roy

Journal of Marine Research

Sea-surface temperature images of the coastal upwelling regions off Northwest Africa show that the core of upwelling is sometimes located far from the coast. This has been documented in three regions that share a common feature, namely a wide and shallow continental shelf. This upwelling feature plays a key role in the ecology of the Canary Current System. It creates an innerfront which provides retention for biological material, e.g. fish eggs and larvae, in the highly productive nearshore environment. An analytical model has been developed based on a two dimensional extension of Ekman's solution. The linear and steady response of …

On The Effect Of A Sill On Dense Water Formation In A Marginal Sea, Doroteaciro Iovino, Fiammetta Straneo, Michael A. Spall

Journal of Marine Research

The properties of water mass transformation in a semi-enclosed basin, separated from the open ocean by a sill and subject to surface cooling, are analyzed both theoretically and numerically using an ocean general circulation model. This study extends previous studies of convection in a marginal sea to the case with a sill. The sill has a strong impact on both the properties of the dense water formed in the interior and on those of the waters flowing out the marginal sea. It results in a colder interior and colder outflow compared to the case with no sill. Dynamically, this is …

Combined Effect Of Wind-Forcing And Isobath Divergence On Upwelling At Cape Bathurst, Beaufort Sea, William J. Williams, Eddy C. Carmack

Journal of Marine Research

Cape Bathurst is at the northeastern end of the Canadian Beaufort Shelf in the southeastern Beaufort Sea where the continental shelf abruptly ends at Amundsen Gulf. In this area, the steep slope east of the cape joins the relatively flat shelf immediately north of the cape leading to strong isobath divergence at the cape. Hydrographic and satellite data show upwelling of nutrient-rich, Pacific-origin water to the surface at Cape Bathurst when surface stress is upwelling-favorable for the Canadian Beaufort Shelf. We suggest that this enhanced upwelling is forced by the adjustment of the along-shelf flow (that is part of upwelling …

Assessing The Wind Field Over The Continental Shelf As A Resource For Electric Power, Richard W. Garvine, Willett Kempton

Journal of Marine Research

To assess the wind power resources of a large continental shelf area, we analyze the 18-year hourly wind records from meteorological stations in the US Middle Atlantic Bight (MAB), comparing areas of coast, estuary, and open shelf. We calculate winds at turbine hub height for the sea breeze compared with synoptic winds and, for each type of site, we compare the seasonal and daily phase match to electrical load. To improve large-scale ocean power resource calculations, we derive an iterative algorithm to determine the surface roughness coefficient (z₀). Our method calculates z₀ for specific times and …

Shelfbreak Frontal Structure And Processes North Of Cape Hatteras In Winter, Glen Gawarkiewicz, James Churchill, Frank Bahr, Chris Linder, Craig Marquette

Journal of Marine Research

The circulation north of Cape Hatteras is complicated by the proximity of the shelfbreak front, the Gulf Stream, and convergent shelf flow from the Middle and South Atlantic Bights. A three-week cruise in this region in January/February, 2005 was undertaken in order to study the structure of the shelfbreak front as it terminates near Cape Hatteras and to quantify the freshwater transport from the Middle Atlantic Bight shelf into the Gulf Stream. Two strongly contrasting conditions were identified. Early in the cruise, the Gulf Stream directly abutted the shelfbreak at Cape Hatteras and drove a northward flow over the continental …

Energetics In Delaware Bay: Comparison Of Two Box Models With Observations, Ana E. Rice, Michael M. Whitney, Richard W. Garvine, Pablo Huq

Journal of Marine Research

A corrected version of an unstratified box model of potential energy anomaly , initially developed by Garvine and Whitney (2006), and a new two-layer box model that allows for stratified and well-mixed conditions are applied to Delaware Bay. The models are applied for the Garvine and Whitney (2006) 1988-1994 study period and in Spring 2003; however, only model results of potential energy anomaly from the latter period are compared to in situ observations obtained outside the bay mouth. Unstratified model results for the two study periods reveal that the river discharge (Ω₁) is the largest potential energy anomaly …

Worms As Wedges: Effects Of Sediment Mechanics On Burrowing Behavior, Kelly M. Dorgan, Sanjay R. Arwade, Peter A. Jumars

Journal of Marine Research

Recent studies document linear elastic response of muddy marine sediments to load and deformation on temporal and spatial scales relevant to animal movement, with burrowers making openings for movement in such sediments by fracture. Cracks propagate through linear elastic solids in mode I (opening-mode crack growth) when the stress intensity factor (K_I) at the crack tip exceeds the material's fracture toughness (K_Ic). Fracture mechanics depend on material stiffness as well as fracture toughness, and we prepared a range of transparent gels that varied in stiffness and fracture toughness to assess the dependence of burrowing …

Evaluating Salt-Fingering Theories, R. Inoue, E. Kunze, L. St. Laurent, R. W. Schmitt, J. M. Toole

Journal of Marine Research

The NATRE fine- and microstructure data set is revisited to test salt-finger amplitude theories. Dependences of the mixing efficiency Γ, microscale buoyancy Reynolds number Re and thermal Cox number Cx_T on 5-m density ratio R_ρ and gradient Richardson number Ri are examined. The observed mixing efficiency is too high to be explained by linear fastest-growing fingers but can be reproduced by wavenumbers 0.5-0.9 times lower than the fastest-growing wavenumber. Constraining these fingers with a hybrid wave/finger Froude number or a finger Reynolds number cannot reproduce the observed trends with R_ρ or Ri, respectively. This suggests that …

Turbulence And Boluses On An Internal Beach, Daniel Bourgault, Dan E. Kelley, Peter S. Galbraith

Journal of Marine Research

In a manner similar to that of surface waves on beaches, high-frequency interfacial waves (IWs) may break when approaching the 'internal coastline,' where the undisturbed pycnocline intersects the shoaling bottom. This process has been studied previously in idealized laboratory and numerical experiments but there are few field observations to document the properties of IWs shoaling on natural internal beaches. This paper presents observations of currents, density and turbulence collected inshore of the break point of an internal beach of the St. Lawrence Estuary. A series of large- and small-amplitude complex-shaped and unorganized internal boluses was observed. The structure of these …

Influence Of Advective Bio-Irrigation On Carbon And Nitrogen Cycling In Sandy Sediments, Taehee Na, Britta Gribsholt, Oleksiy S. Galaktionov, Tongsup Lee, Filip J. R. Meysman

Journal of Marine Research

In sandy sediments, the burrow ventilation activity of benthic macrofauna can generate substantial advective flows within the sediment surrounding their burrows. Here we investigated the effects of such advective bio-irrigation on carbon and nitrogen cycling in sandy sediments. To this end, we combined a range of complementary experimental and modelling approaches in a microcosm study of the lugworm Arenicola marina (Polychaeta: Annelida). Bio-irrigation rates were determined using uranine as a tracer, while benthic fluxes of oxygen (O₂), total carbon dioxide (TCO₂), dissolved inorganic nitrogen (NH₄⁺, ΣNO₂⁻ + NO₃⁻) …

Richard W. Garvine (1940 –2007), Kenneth H. Brink, Glen G. Gawarkiewicz

Journal of Marine Research

Richard Garvine passed away on December 10, 2007 of pancreatic cancer, and the ocean science community lost a respected, humane leader whose impact will endure on several levels. Rich was born in 1940 in Pottstown, Pennsylvania. His undergraduate degree in aerospace engineering at M.I.T. was followed by a Ph.D. at Princeton University in 1965, also in aerospace engineering. He was hired by the General Electric Space Sciences Laboratory as a theoretical aerodynamicist, but in 1969, perhaps prodded by a downturn in the aerospace field, he made the rather dramatic shift to a position as an Assistant Professor of Oceanography at …

Ocean Current Observations From Nares Strait To The West Of Greenland: Interannual To Tidal Variability And Forcing, Andreas Münchow, Humfrey Melling

Journal of Marine Research

During 2003–06, as part of the Arctic Sub-Arctic Ocean Flux (ASOF) experiment, an array of oceansensing instruments was deployed at 80.5N latitude to investigate the flux of seawater from the Arctic Ocean via Nares Strait, the pathway to the west of Greenland. Three-year measurements of current from this experiment provide, for the first time at periods longer than a single season, the seawater flux and its variability via this important pathway. Below 30-m depth the average flux of volume 2003–06 was 0.57±0.09 Sv (1 Sv = 10⁶ m³ s^–1) southward over a 38-km wide section reaching …

Mean Energy Balance In The Tropical Pacific Ocean, Jaclyn N. Brown, Alexey V. Fedorov

Journal of Marine Research

The maintenance of the ocean general circulation requires energy input from the wind. Previous studies estimate that the mean rate of wind work (or wind power) acting on the surface currents over the global ocean amounts to 1.1 TW (1 TW = 10¹² Watts), though values remain highly uncertain. By analyzing the output from a range of ocean-only models and data assimilations, we show that the tropical Pacific Ocean contributes around 0.2 to 0.4 TW, which is roughly half of the total tropical contribution. Not only does this wind power represent a significant fraction of the total global energy …

Modeling Estuarine Ingress Of Blue Crab Megalopae: Effects Of Temporal Patterns In Larval Release, Charles E. Tilburg, Colleen D. Kernehan, Alex Andon, Charles E. Epifanio

Journal of Marine Research

The Atlantic blue crab Callinectes sapidus is an important predator in estuarine ecosystems and supports a large commercial fishery throughout its range. Settlement of blue crab megalopae in juvenile nurseries is episodic and is controlled by the combined effect of buoyancy- and wind-driven transport processes. Modeling studies have succeeded in hind-casting the temporal pattern of megalopal settlement but not the magnitude of individual settlement events. This shortcoming has been attributed to the lack of information concerning larval release by the adult spawning population. In this paper we present results of a set of field and modeling studies designed to test …

Episodic Downwelling Predicts Recruitment Of Atlantic Cod, Greenland Cod And White Hake To Newfoundland Coastal Waters, D. W. Ings, R. S. Gregory, D. C. Schneider

Journal of Marine Research

Recruitment in marine fish is influenced by abiotic and biotic processes operating at many spatial and temporal scales. Annual recruitment to fisheries has received more attention at the scale of the population than at finer temporal scales, where spatially heterogeneous biological processes modify year-class success. We tested two hypotheses: (1) that recruitment of marine fish to the nearshore benthos at a fine temporal scale is determined by downwelling associated with onshore winds and (2) that fish arrival nearshore is related to tidal stage. During summer and autumn 1998 to 2001 and late spring to autumn 2002, we monitored recruitment of …

Measuring Turbulent Large-Eddy Structures With An Adcp. 1. Vertical Velocity Variance, A. E. Gargett, A. E. Tejada-Martínez, C. E. Grosch

Journal of Marine Research

Two different turbulent flows, Langmuir supercells and unstable convection, have been sampled with a VADCP, an acoustic Doppler current profiler (ADCP) with an additional vertical (V) beam. Direct measurements of the profile of vertical velocity variance provided by the vertical beam are used to calculate observational response functions for algorithms used to derive vertical velocity from the 4 beams of a standard ADCP. A theoretical response function derived for the vertical velocity estimate from a single pair of opposed slant beams illustrates the importance of large-scale quasi-coherent flow structures, as well as effects of different angles of slant beams from …

Ocean Color Data Assimilation With Material Conservation For Improving Model Estimates Of Air-Sea Co2 Flux, John C. P. Hemmings, Rosa M. Barciela, Michael J. Bell

Journal of Marine Research

A nitrogen balancing scheme for ocean color data assimilation in general circulation models is described and its potential for improving air-sea CO₂ flux estimates is demonstrated. Given increments for phytoplankton, obtainable from a univariate surface chlorophyll analysis, the scheme determines mixed layer concentration increments for the other nitrogen pools: zooplankton, detritus and dissolved inorganic nitrogen (DIN). The fraction of the phytoplankton increment to be balanced by changing DIN varies dynamically with the likely contributions of phytoplankton growth and loss errors to the error in the background state. Further increments are applied below the mixed layer wherever positive DIN increments …

The Impact Of Spatial Wind Variations On Freshwater Transport By The Alaska Coastal Current, John Rogers-Cotrone, Alexander E. Yankovsky, Thomas J. Weingartner

Journal of Marine Research

The Alaska Coastal Current (ACC) is located in a region with prevailing downwelling-favorable winds, flows over a long stretch of coastline (over 2000 km), and is driven by multiple sources of freshwater discharge totaling 24000 m³ s^–1 along its length. Using the Regional Ocean Modeling System (ROMS) we attempt to determine how spatially variable winds affect the downstream transport of freshwater along a long coastline with nearly continuous sources of freshwater. The model domain represents a fraction of the ACC region and periodic boundary conditions are applied to allow propagation of the buoyant flow from upstream. The model …

Observations Of Coastal Upwelling Off Uruguay Downshelf Of The Plata Estuary, South America, Felipe Pimenta, Richard W. Garvine, Andreas Münchow

Journal of Marine Research

We analyze hydrographic and current observations of an upwelling center off eastern South America on the Uruguayan coast (∼35S) and downshelf from the Rio de la Plata estuary. Our observations show that the buoyancy-driven subtidal alongshore circulation is modulated by winds. During the winter, strong upwelling-favorable local winds forced the Rio de la Plata buoyant plume poleward. In the summer, the plume detached from the coast with warm and saline subtropical waters intruding from the north. These waters bounded the upwelling of cold waters in the nearshore area off Uruguay. A shallow submarine canyon cutting obliquely across the shelf facilitates …

Seasonal Dynamics Of The Depth And Rate Of Anaerobic Oxidation Of Methane In Aarhus Bay (Denmark) Sediments, A. W. Dale, D. R. Aguilera, P. Regnier, H. Fossing, N. J. Knab, B. B. Jørgensen

Journal of Marine Research

A reactive-transport model has been applied to investigate the dynamics of the sulfate-methane transition zone (SMTZ) in nearshore sediments of Aarhus Bay (Denmark). The sediments are influenced by seasonal variations of temperature and particulate organic carbon (POC) deposition flux at the sediment-water interface. Initially, the model was calibrated at steady state using field data collected at two sites (M1 and M5) in December 2004, and included a dynamic gas phase which determines the depth of the SMTZ. Simulations were then performed under transient conditions of heat propagation in the porous medium, which influenced the solubility of gaseous methane, the diffusion …

Transport Of Blue Crab Larvae In The Middle Atlantic Bight: A Wet And Windy Journey, Charles E. Epifanio, Charles E. Tilburg

Journal of Marine Research

This paper describes the 25-year evolution of a program of research into the larval ecology of the Atlantic blue crab (Callinectes sapidus) near the mouth of Delaware Bay on the east coast of the USA (38.5N, 75.1W). The investigation began as a biological study; eventually incorporated a physical component; and finally added a mathematical modeling aspect. Early work was strictly biological and demonstrated that C. sapidus larvae are exported from the estuary to the adjacent coastal ocean where larval development occurs. Once this fact was established, it was clear that further progress demanded an understanding of shelf circulation. …

Historical Datasets Of Dugong (Dugong Dugon) Observations In The Kimberley Region Of Western Australia - Data Report - Report No. 2008-03, David K. Holley, R. I.T. Prince

Research outputs pre 2011

Research Need and Objective :

Many sections of the northern WA coastline have become heavily industrialised in the last three decades particularly throughout the Pilbara region where offshore and onshore oil and gas exploration and processing facilities are abundant. There have been recent moves to develop similar industry along the Kimberley coast to access the Browse Basin, a 140,000 Km2 offshore gas field approximately 300km off the Kimberley Coast. This has resulted in extensive debate and the need to define the natural values of this region, which is considered to be one of the world’s most ecologically diverse (WWF 2008). …

A Mechanism For Establishment And Maintenance Of The Meridional Overturning In The Upper Ocean, Timour Radko

Journal of Marine Research

A two-dimensional analytical residual-mean model of the meridional overturning in the upper ocean is presented which illustrates dynamics of the interaction between the Northern and Southern hemispheres. The theory is based on the semi-adiabatic approximation in which all diabatic processes are confined to the upper mixed layer. The overturning circulation is driven directly by the wind forcing which, in our model, is affected by the sea-surface temperature distribution. The surface boundary conditions are symmetric with respect to the equator, and therefore one of the steady state solutions represents a symmetric flow characterized by the absence of the inter-hemispheric buoyancy fluxes. …

Equatorial Deep Jets Triggered By A Large Vertical Scale Variability Within The Western Boundary Layer, Marc D'Orgeville, Bach Lien Hua, Hideharu Sasaki

Journal of Marine Research

The response of the deep equatorial ocean to an oscillatory baroclinic western boundary current is investigated in a continuously stratified primitive equation model. The symmetry of the current about the equator is such that mixed Rossby-gravity (MRG) waves are excited in the western part of the equatorial ocean. Depending on the forcing frequency, short to long scale (when compared to equatorial Rossby radius) monochromatic MRG waves are selected. The subsequent MRG wave destabilization generally leads to a much higher vertical mode response than the forced MRG wave mode. In a channel, short MRG waves are destabilized by shear instability (Hua …

Mean Jets, Mesoscale Variability And Eddy Momentum Fluxes In The Surface Layer Of The Antarctic Circumpolar Current In Drake Passage, Y. D. Lenn, T. K. Chereskin, J. Sprintall, E. Firing

Journal of Marine Research

High-resolution Acoustic Doppler Current Profiler (ADCP) observations of surface-layer velocities in Drake Passage, comprising 128 sections over a period of 5 years, are used to study the surface-layer circulation of the Antarctic Circumpolar Current (ACC). These observations resolve details of the mean flow including the topographic control of the mean Subantarctic Front (SAF) and the multiple filaments of the Polar Front (PF) and Southern ACC Front (SACCF) that converge into single mean jets as the ACC flows through Drake Passage. Subsurface definitions of the SAF and PF applied to expendable bathythermograph temperatures generally coincide with mean jets, while the SACCF …

Plankton Accumulation And Transport In Propagating Nonlinear Internal Fronts, A. Scotti, J. Pineda

Journal of Marine Research

Accumulation and transport of plankton in fronts propagating across-shore is a process of considerable ecological importance for many inhabitants of the littoral zone, since it links the offshore larval pool with the juvenile and adult inshore habitat. Several field studies have shown that larval plankton accumulates in fronts, but have failed to give a conclusive proof that effective Lagrangian transport takes place. A few process-oriented numerical studies have lent support to the idea, but the scope of their results is limited by the two-dimensional nature of the flows considered and by the simple model used to account for the behavior …

Near-Bottom Horizontal Transfer Of Particulate Matter In The Palamós Submarine Canyon (Nw Mediterranean), J. Martin, A. Palanques, P. Puig

Journal of Marine Research

From March to November 2001, six current meters equipped with turbidimeters were moored 12 meters above the bottom inside the Palamós submarine canyon and on the adjacent slope. Horizontal particle fluxes were calculated from current and suspended sediment concentration data. This work aims to evaluate the advective sediment fluxes taking place in the Palamós canyon region, and to discern the nature and time-scales of the processes involved in the across-margin transfer of particles over the study period. Near-bottom currents inside the canyon were constrained by the local topography and displayed a high spatio-temporal variability. The net near-bottom transport of suspended …

Simulations Of Phytoplankton Species And Carbon Production In The Equatorial Pacific Ocean 1. Model Configuration And Ecosystem Dynamics, Baris Salihoglu, Eileen E. Hofmann

Journal of Marine Research

The primary objective of this research is to investigate phytoplankton community response to variations in physical forcing and biological processes in the Cold Tongue region of the equatorial Pacific Ocean at 0N, 140W. This research objective was addressed using a one-dimensional multicomponent lower trophic level ecosystem model that includes detailed algal physiology, such as spectrally-dependent photosynthetic processes and iron limitation on algal growth. The ecosystem model is forced by a one-year (1992) time series of spectrally-dependent light, temperature, and water column mixing obtained from a Tropical Atmosphere-Ocean (TAO) Array mooring. Autotrophic growth is represented by five algal groups, which have …

Influence Of Environmental Forcings On The Seasonality Of Dissolved Oxygen And Nutrients In The Bay Of Bengal, S. Sardessai, N. Ramaiah, S. Prasanna Kumar, S. N. De Sousa

Journal of Marine Research

Studies on seasonal variability of oxygen and nutrients during three seasons namely SW monsoon, fall intermonsoon and spring intermonsoon indicate influence of physical forcings on the distribution of these hydrochemical properties in the subsurface layer. In the open ocean the Minimum Oxygen Layer (MOL ≤10 mu Mol L^-1) during the southwest monsoon and fall intermonsoon is mostly confined to the north of 11N due to the penetration of high salinity water in the deeper waters of the central Bay. During spring intermonsoon MOL is mostly confined to the northern region between 14 to 20N with a narrow band …

A Fast Numerical Solution To The General Mass-Conservation Equation For Solutes And Solids In Aquatic Sediments, Peter Berg, Dennis Swaney, Søren Rysgaard, Bo Thamdrup, Henrik Fossing

Journal of Marine Research

Mathematical modeling of species transformations in aquatic sediments is usually based on numerical solutions to the same general one-dimensional mass-conservation equation and is likely to require substantial computation time. In this paper we present a fast numerical solution to this equation. The solution is suited for both single and multi-component models and it is based on an implicit control volume discretization of the general mass-conservation equation. The solution consists of two algorithms, one that decomposes the discretization matrix once and one that subsequently produces multiple solutions with minimal computational effort. A unique feature of these algorithms is that values of …