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Floats And Ƒ/H, J. H. Lacasce Jan 2000

Floats And Ƒ/H, J. H. Lacasce

Journal of Marine Research

The sensitivity of oceanic float dispersion to f/H, where H is a spatially filtered representation of the water depth, is examined with floats from the Atlantic and Pacific oceans. The first and second moments of the displacements relative to f/H were found and compared to those for zonal and meridional displacements. In all cases, the moments relative to f/H display equal or greater anisotropy than those relative to geographical coordinates, suggesting a preferred tendency for spreading along f/H. In regions where the topography is flat (at the equator, in the …

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The Impact Of Accelerating Land-Use Change On The N-Cycle Of Tropical Aquatic Ecosystems: Current Conditions And Projected Changes, J. A. Downing, M. Mcclain, R. Twilley, J. M. Melack, J. Elser, Nancy N. Rabalais, W. M. Lewis Jr., R. Eugene Turner, J. Corredor, D. Soto, A. Yanez Arancibia, J. A. Kopaska, R. W. Howarth Jul 1999

The Impact Of Accelerating Land-Use Change On The N-Cycle Of Tropical Aquatic Ecosystems: Current Conditions And Projected Changes, J. A. Downing, M. Mcclain, R. Twilley, J. M. Melack, J. Elser, Nancy N. Rabalais, W. M. Lewis Jr., R. Eugene Turner, J. Corredor, D. Soto, A. Yanez Arancibia, J. A. Kopaska, R. W. Howarth

Faculty Publications

Published data and analyses from temperate and tropical aquatic systems are used to summarize knowledge about the potential impact of land-use alteration on the nitrogen biogeochemistry of tropical aquatic ecosystems, identify important patterns and recommend key needs for research. The tropical N-cycle is traced from pre-disturbance conditions through the phases of disturbance, highlighting major differences between tropical and temperate systems that might influence development strategies in the tropics. Analyses suggest that tropical freshwaters are more frequently N-limited than temperate zones, while tropical marine systems may show more frequent P limitation. These analyses indicate that disturbances to pristine tropical lands will …

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Imperfections Of The North Atlantic Wind-Driven Ocean Circulation: Continental Geometry And Windstress Shape, Henk A. Dijkstra, M. Jeroen Molemaker Jan 1999

Imperfections Of The North Atlantic Wind-Driven Ocean Circulation: Continental Geometry And Windstress Shape, Henk A. Dijkstra, M. Jeroen Molemaker

Journal of Marine Research

Multiple equilibria of the wind-driven gyres have been found in idealized quasi-geostrophic and shallow water models. In this paper we demonstrate that multiple equilibria persist within a reduced gravity shallow water model under quite realistic continental geometry and windstress forcing for the North Atlantic. Multiple mean flow patterns of the Gulf Stream exist and differ with respect to their separation behavior along the North American coast. The origin of these equilibria is investigated by determining the structure of steady solutions within a hierarchy of equivalent barotropic ocean models using continuation techniques. Within each model, the magnitude of lateral friction is …

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Evaluating Eddy Mixing Coefficients From Eddy-Resolving Ocean Models: A Case Study, A. M. Treguier Jan 1999

Evaluating Eddy Mixing Coefficients From Eddy-Resolving Ocean Models: A Case Study, A. M. Treguier

Journal of Marine Research

A numerical model of a baroclinically unstable jet in a zonally periodic channel is used to analyze mesoscale eddy fluxes and their relationship with the gradients of the mean flow. The quasi-geostrophic approximation proves the best way to calculate potential vorticity fluxes in the primitive equation model. Away from the surface layers, eddy fluxes of potential density are consistent with advection by eddy-induced velocities v* and w* as suggested by Gent et al. (1995). Eddies mix potential vorticity along isopycnals, so that v* is related to the gradients of potential vorticity rather than potential density as …

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Biogeochemistry Of Dimethylsulfide In The South China Sea, Gui-Peng Yang, Xin-Tong Liu, Li Li, Zheng-Bin Zhang Jan 1999

Biogeochemistry Of Dimethylsulfide In The South China Sea, Gui-Peng Yang, Xin-Tong Liu, Li Li, Zheng-Bin Zhang

Journal of Marine Research

The distribution of dimethylsulfide (DMS) was studied in surface seawater and vertical profiles at nineteen stations in the Nansha Islands sea area of the South China Sea. The concentrations of DMS in surface-layer (0-1 m) seawater vary from 64 to 140 ng S/L with high values found in the productive regions, in agreement with the horizontal distribution of chlorophyll a. The vertical profiles of DMS show a single peak shape with maximum concentrations occurring at depths between 30-75 m. The DMS concentrations are correlated with chlorophyll a levels both in the upper 20 m of seawater as well as …

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Mode Waters And Subduction Rates In A High-Resolution South Atlantic Simulation, Anne P. De Miranda, Bernard Barnier, William K. Dewar Jan 1999

Mode Waters And Subduction Rates In A High-Resolution South Atlantic Simulation, Anne P. De Miranda, Bernard Barnier, William K. Dewar

Journal of Marine Research

Water mass production and destruction in the subtropical South Atlantic gyre is studied. A high resolution numerical model is used to examine regional mode water formation and estimate the associated instantaneous and mean subduction rates. Primitive equation dynamics expressed in depth following (sigma) coordinates are employed. The main hydrographic and kinematic features of the South Atlantic are faithfully reproduced by the model. In particular, the principle current systems appear and the model exhibits a sequence of ventilated potential vorticity minima on density surfaces coinciding with those of observed South Atlantic mode waters. The formation sequence within the model of these …

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The Importance Of Open-Boundary Estimation For An Indian Ocean Gcm-Data Synthesis, Kate Q. Zhang, Jochem Marotzke Jan 1999

The Importance Of Open-Boundary Estimation For An Indian Ocean Gcm-Data Synthesis, Kate Q. Zhang, Jochem Marotzke

Journal of Marine Research

The Indian Ocean general circulation is estimated by fitting the MIT Ocean General Circulation Model to the annual mean climatological hydrography and surface forcing, using the model and its computer-generated adjoint. Open boundary conditions are implemented to the west of the Indonesian Archipelago and near 30S. The approach simultaneously optimizes the initial conditions of the hydrographic fields, surface fluxes, and the open boundary conditions (temperature, salinity, and horizontal velocities). Compared to previous results obtained in a closed domain, the estimated velocity field shows a marked improvement near the southern boundary, with a reasonably strong Agulhas Current leaving the model domain. …

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Bioturbation And Particle Transport In Carolina Slope Sediments: A Radiochemical Approach, W. L. Fornes, D. J. Demaster, L. A. Levin, N. E. Blair Jan 1999

Bioturbation And Particle Transport In Carolina Slope Sediments: A Radiochemical Approach, W. L. Fornes, D. J. Demaster, L. A. Levin, N. E. Blair

Journal of Marine Research

In situ tracer experiments investigated short-term sediment mixing processes at two Carolina continental margin sites (water depth = 850 m) characterized by different organic C fluxes, 234Th mixing coefficients (Db) and benthic assemblages. Phytoplankton, slope sediment, and sand-sized glass beads tagged with 210Pb, 113Sn, and 228Th, respectively, were placed via submersible at the sediment-water interface at both field sites (Site I off Cape Fear, and Site III off Cape Hatteras). Experimental plots were sampled at 0, 1.5 days, and 90 days after tracer emplacement to examine short-term, vertical transport. Both sites are initially …

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Diagenesis Of Planktonic Fatty Acids And Sterols In Long Island Sound Sediments: Influences Of A Phytoplankton Bloom And Bottom Water Oxygen Content, Ming-Yi Sun, Stuart G. Wakeham Jan 1999

Diagenesis Of Planktonic Fatty Acids And Sterols In Long Island Sound Sediments: Influences Of A Phytoplankton Bloom And Bottom Water Oxygen Content, Ming-Yi Sun, Stuart G. Wakeham

Journal of Marine Research

Diagenesis of organic matter in coastal sediments from Long Island Sound (LIS) was investigated by measuring fatty acids and sterols in (1) a time-series of surface sediment samples over a spring phytoplankton bloom; and (2) sediment cores collected during and after a bloom at two sites with distinctively different bottom-water oxygen contents. Time-dependent distributions of sedimentary fatty acids and sterols in LIS were strongly affected by pulsed inputs from the overlying water column, variations in benthic community, and redox-related degradation processes. The phytoplankton bloom delivered an intense pulse of unsaturated fatty acids (e.g., 16:1(ω7) and 20:5) to the surface sediments. …

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Sensitivity Of Primary Production To Different Eddy Parameterizations: A Case Study Of The Spring Bloom Development In The Northwestern Mediterranean Sea, Marina Lévy, Martin Visbeck, Naomi Naik Jan 1999

Sensitivity Of Primary Production To Different Eddy Parameterizations: A Case Study Of The Spring Bloom Development In The Northwestern Mediterranean Sea, Marina Lévy, Martin Visbeck, Naomi Naik

Journal of Marine Research

The abilities of the Gent and McWilliams (1990) (GM) and Horizontal Diffusion (HD) eddyparameterizations to represent the mesoscale effects relevant for primary production are compared and analyzed. Following Lévy et al. (1999a), this is done in the case study of the spring bloom that follows the formation of a dense water patch in the northwestern Mediterranean Sea. It is shown that, unlike HD, the use of the GM parameterization can capture many aspects of the primary production enhancement associated with the restratifying action of mesoscale eddies. However, predicted primary production, when using the GM parameterization, is sensitive to the GM's …

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The Lattice Boltzmann Method As A Basis For Ocean Circulation Modeling, Rick Salmon Jan 1999

The Lattice Boltzmann Method As A Basis For Ocean Circulation Modeling, Rick Salmon

Journal of Marine Research

We construct a lattice Boltzmann model of a single-layer, "reduced gravity" ocean in a square basin, with shallow water or planetary geostrophic dynamics, and boundary conditions of no slip or no stress. When the volume of the moving upper layer is sufficiently small, the motionless lower layer outcrops over a broad area of the northern wind gyre, and the pattern of separated and isolated western boundary currents agrees with the theory of Veronis (1973). Because planetary geostrophic dynamics omit inertia, lattice Boltzmann solutions of the planetary geostrophic equations do not require a lattice with the high degree of symmetry needed …

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Sensitivity Of Ecosystem Parameters To Simulated Satellite Ocean Color Data Using A Coupled Physical-Biological Model Of The North Atlantic, Jim Gunson, Andreas Oschlies, Véronique Garçon Jan 1999

Sensitivity Of Ecosystem Parameters To Simulated Satellite Ocean Color Data Using A Coupled Physical-Biological Model Of The North Atlantic, Jim Gunson, Andreas Oschlies, Véronique Garçon

Journal of Marine Research

A means of assimilating simulated satellite ocean color data with a coupled physical-biological model of the North Atlantic Ocean is implemented, allowing the relative sensitivities of different biological parameters to those data to be investigated. The model consists of an eddy-permitting general circulation model derived from the WOCE Community Modeling Effort and a nitrogen-based, four-compartment NPZD marine ecosystem model. Many of the parameters in marine ecosystem models are poorly known and via assimilation, we hope to better constrain their values. The control parameters chosen for the variational assimilation are the model parameters involved in parameterizations of recycling as these are …

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Radiative Damping Of Near-Inertial Oscillations In The Mixed Layer, N. J. Blamforth, W. R. Young Jan 1999

Radiative Damping Of Near-Inertial Oscillations In The Mixed Layer, N. J. Blamforth, W. R. Young

Journal of Marine Research

An idealized model of the transmission of near-inertial waves from the mixed layer into the deeper ocean is studied in order to assess the combined effects of background geostrophic vorticity and the planetary vorticity gradient. The model geostrophic flow is steady and barotropic with a streamfunction ψ =-Ψ cos (2αy); the planetary vorticity gradient is modeled using the β-effect. After projection onto vertical modes, each modal amplitude satisfies a Schrödinger-like wave equation (in y and t) in which βy + (ψyy/2) plays the role of a potential. With realistic parameter values, this potential function …

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Wind-Driven Mixed Layer And Coastal Upwelling Processes Off The South Coast Of South Africa, Eckart H. Schumann Jan 1999

Wind-Driven Mixed Layer And Coastal Upwelling Processes Off The South Coast Of South Africa, Eckart H. Schumann

Journal of Marine Research

Most coastal mixed layer and upwelling investigations have concentrated on the more important fisheries regions situated on the west coasts of the continents, while this paper analyzes conditions on the zonally-orientated south coast of South Africa. Most of the data originate from a short measurement program in the southern summer of 1995, involving both CTD measurements from a small boat and data from a temperature array and coastal sea surface temperature (SST). Limited mixed layer statistics are derived and yield results similar to those of Lentz (1992), although a lack of current measurements precludes any assessment of the Ekman drift. …

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Spatial And Temporal Variability Of Turbulent Mixing In An Estuary, Hartmut Peters Jan 1999

Spatial And Temporal Variability Of Turbulent Mixing In An Estuary, Hartmut Peters

Journal of Marine Research

Observations with a microstructure/CTD profiler and an ADCP during five cruises in 1994/95 provide a glance at the turbulent mixing climate of a partially mixed estuary, the Hudson River. The cruises took place under widely varying conditions of river discharge and external forcing by water level fluctuations in New York Bight. Tidal and fortnightly variability patterns of stratification, shear and mixing characteristics were qualitatively repeatable, largely following the description of Peters (1997). (i) Longer-term variations of buoyancy frequency and Richardson number (Ri) during flood were weakly correlated with the river discharge. (ii) All flood tides had substantial mixing. …

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Interannual Variability In The Mesoscale Distribution Of The Depth Of The Upper Boundary Of The Oxygen Minimum Layer Off Northern Chile (18–24s): Implications For The Pelagic System And Biogeochemical Cycling, Carmen E. Morales, Samuel E. Hormazábal, José Luis Blanco Jan 1999

Interannual Variability In The Mesoscale Distribution Of The Depth Of The Upper Boundary Of The Oxygen Minimum Layer Off Northern Chile (18–24s): Implications For The Pelagic System And Biogeochemical Cycling, Carmen E. Morales, Samuel E. Hormazábal, José Luis Blanco

Journal of Marine Research

The low oxygen concentration (<2 ml L-1) at relatively shallow depths (<100 m) in the coastal upwelling zone and in the adjacent oceanic area is a distinct feature of the eastern boundary Humboldt Current System (HCS) off Peru and northern Chile; it affects the distribution of pelagic organisms and is associated with an important denitrification regime in the water column. Nevertheless, little information is available about the spatial and temporal variability in the distribution of the Oxygen Minimum Layer (OML) present in the HCS and the impact of its variability upon the pelagic system and biogeochemical cycles in the region. The present study reviews the oceanographic data obtained for the area off northern Chile (ca. 18 to 24S, out to 370 km), between 1980 and 1997, with the aim of characterizing the depth distribution of the upper boundary of the OML (1 ml L-1 iso-oxyline, representing also the oxycline) and investigating the association of its interannual variability with changes in coastal sea level and in the equatorial and local thermoclines. The depth of the upper boundary of the OML undergoes pronounced deepening during the occurrence of warm ENSO (El Niño Southern Oscillation) events over the whole area of study, and this, in turn, determines a condition of higher oxygen concentrations in the top 100 m layer. These changes follow closely the patterns of interannual variability in coastal sea level and depth …

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A Seasonal Succession Of Physical/Biological Interaction Mechanisms In The Sargasso Sea, J. D. Wiggert, T. C. Granata, T. D. Dickey, J. Marra Jan 1999

A Seasonal Succession Of Physical/Biological Interaction Mechanisms In The Sargasso Sea, J. D. Wiggert, T. C. Granata, T. D. Dickey, J. Marra

Journal of Marine Research

Six months of concurrent, co-located physical and bio-optical time series from a moored array deployed in the Sargasso Sea during 1987 have been analyzed by combining standard Fourier analysis techniques with a unique presentation method. The spectral information obtained from the time series analysis covers four orders of magnitude in frequency space. This is especially useful for revealing temporal variations in high frequency variance and the physical/biological interactions that occur at these frequencies. The presentation method used here consists of time/frequency distributions of normalized variance and squared coherence that resulted from the time series analysis. These reveal a seasonal succession …

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On The Seasonal Nitrogen Dynamics Of The Baltic Proper Biogeochemical Reactor, Kari Eilola, Anders Stigebrandt Jan 1999

On The Seasonal Nitrogen Dynamics Of The Baltic Proper Biogeochemical Reactor, Kari Eilola, Anders Stigebrandt

Journal of Marine Research

During the last decade it has become increasingly obvious that the turnover of dissolved organic nitrogen DON in marine environments is quite vigorous. This paper quantifies the turnover of DON in the Baltic proper regarded as a biogeochemical reactor. In a nitrogen model for the reactor, dissolved inorganic nitrogen DIN, DON and molecular N, fixed by cyanobacteria, can be used for plant production. The decomposition of particulate organic matter is assumed to produce DON and DIN as end products in the proportions (1- η) to η (0 ≤ η ≤ 1). The model includes two internal sink processes, denitrification and …

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On The Influence Of The Parameterization Of Lateral Boundary Layers On The Thermohaline Circulation In Coarse-Resolution Ocean Models, Thierry Huck, Andrew J. Weaver, Alain Colin De Verdière Jan 1999

On The Influence Of The Parameterization Of Lateral Boundary Layers On The Thermohaline Circulation In Coarse-Resolution Ocean Models, Thierry Huck, Andrew J. Weaver, Alain Colin De Verdière

Journal of Marine Research

Because of the first order geostrophic balance in the ocean interior, the parameterization of lateral boundary layers has more influence than the parameterization of viscosity on the thermohaline overturning and the deep water properties in coarse-resolution ocean circulation models. Different formulations of momentum dissipation and associated boundary conditions are implemented within a planetary-geostrophic ocean circulation model for a Cartesian coordinate, flat-bottomed, β-plane, with restoring boundary conditions for the surface density and zero wind stress. Traditional Laplacian friction with a no-slip boundary condition produces an interior circulation in good agreement with geostrophy and the Sverdrup balance, but generates very large vertical …

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Enhanced Degradation Of Algal Lipids By Benthic Macrofaunal Activity: Effect Of Yoldia Limatula, Ming-Yi Sun, Robert C. Aller, Cindy Lee, Stuart G. Wakeham Jan 1999

Enhanced Degradation Of Algal Lipids By Benthic Macrofaunal Activity: Effect Of Yoldia Limatula, Ming-Yi Sun, Robert C. Aller, Cindy Lee, Stuart G. Wakeham

Journal of Marine Research

We used the protobranch bivalve, Yoldia limatula, in a series of incubation experiments to test whether activities of deposit-feeding macrofauna cause differences in lipid degradation processes relative to controls lacking macrofauna. Uniformly 13C-labeled algae (13C > 98%) were used as a source of fresh planktonic lipids, easily distinguished from bulk sedimentary lipids by GC/MS. Variations in concentration of major lipid components ([16:1(ω7), 16:0 and 18:1(ω9)] fatty acids and phytol) were followed as a function of time in incubations with and without Yoldia. Results showed that Yoldia can significantly enhance the degradation of planktonic lipids in sediments. …

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Salt Fingers In Three Dimensions, Timour Radko, Melvin E. Stern Jan 1999

Salt Fingers In Three Dimensions, Timour Radko, Melvin E. Stern

Journal of Marine Research

Three dimensional (3D) numerical calculations are made for a vertically unbounded fluid with initially uniform vertical gradients of sugar ( S ) and salt ( T ), where τ = κS/κT = 1/3 is the diffusivity ratio, and the molecular viscosity is ν >> κT. The latter inequality allows us to neglect the nonlinear term in the momentum equation, while retaining such terms in the T-S equations. The discrete 3D Fourier spectrum resolves the fastest growing horizontal wavelength, as well as the depth independent Fourier component. Unlike previous calculations for the pure 2D case the finite …

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Near-Surface Circulation And Kinetic Energy In The Tropical Indian Ocean Derived From Lagrangian Drifters, S. S. C. Shenoi, P. K. Saji, A. M. Almeida Jan 1999

Near-Surface Circulation And Kinetic Energy In The Tropical Indian Ocean Derived From Lagrangian Drifters, S. S. C. Shenoi, P. K. Saji, A. M. Almeida

Journal of Marine Research

Trajectories of 412 satellite-tracked drifting buoys deployed in the tropical Indian Ocean have been analyzed to document the surface circulation and kinetic energy field. Only drifters drogued at 15 m depth and having drag area ratio greater than 35 are used to estimate current velocities. Unlike in earlier studies, the widening of the Equatorial Jet in the eastern equatorial Indian Ocean and the westward flow at the equator during July–August are apparent in the present data set. The comparison of drifter data with the seasonal mean dynamic topography (0/1000 db) shows that the surface circulation pattern inferred from dynamic topography …

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Bering Sea Deep Circulation: Water Properties And Geopotential, Ronald K. Reed, Calvin W. Mordy Jan 1999

Bering Sea Deep Circulation: Water Properties And Geopotential, Ronald K. Reed, Calvin W. Mordy

Journal of Marine Research

Deep temperature and silicate data from the Bering Sea demonstrate patterns that are consistent and allow inference of near-bottom circulation. The cold source water enters Kamchatka Strait and mainly moves toward the southeast through a narrow topographic gap and into Bowers Basin. There is also a narrow, coherent flow eastward, and eventually southeastward, near the steep flank of Bowers Ridge. At levels ~100–300 m above the bottom, there is a suggestion of upward motion near the margins of much of the deep Bering Sea. Near-bottom geopotential gradients, referred to 3000 db, are in agreement with flow inferred from water properties.

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Experiments On Waves Trapped Over The Continental Slope And Shelf In A Continuously Stratified Rotating Ocean, And Their Incidence On A Canyon, Daniel L. Codiga, Dominique P. Renouard, Adam M. Fincham Jan 1999

Experiments On Waves Trapped Over The Continental Slope And Shelf In A Continuously Stratified Rotating Ocean, And Their Incidence On A Canyon, Daniel L. Codiga, Dominique P. Renouard, Adam M. Fincham

Journal of Marine Research

Continental margins form a waveguide for topographic Rossby waves, which can be trapped to the bottom by continuous stratification and concentrated over the continental slope while propagating along the coast. We present results of laboratory wave simulations designed to keep as many dimensionless numbers (Rossby, Burger, normalized frequency, wave steepness, geometrical, Ekman, and Reynolds) as possible similar to those of coastal-trapped waves, such as are observed in coastal regions around the world. The 13-m diameter rotating tank is salt-stratified and a continental slope joins a shallow shelf region along the outer tank circumference to a deep central region. The velocity …

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Enzymatically Hydrolyzable Amino Acids In North Sea Sediments And Their Possible Implication For Sediment Nutritional Values, B. Dauwe, J. J. Middelburg, P. Van Rijswijk, J. Sinke, P. M. J. Herman, C. H. R. Heip Jan 1999

Enzymatically Hydrolyzable Amino Acids In North Sea Sediments And Their Possible Implication For Sediment Nutritional Values, B. Dauwe, J. J. Middelburg, P. Van Rijswijk, J. Sinke, P. M. J. Herman, C. H. R. Heip

Journal of Marine Research

The nutritional value of peptidic material in five North Sea sediments that differ in organic matter quality has been investigated with an enzymatic approach measuring the digestibility (rate constant k of proteolysis by protease) and the proportion of bioavailable fraction of amino acids (%EHAA-i:THAA). The bioavailable fraction in sediments varied between 14-50% EHAA-i:THAA and was generally lower than in potential source organisms such as algae (40-43%), plankton (~80%) and bacteria (57-72%). The rate of proteolysis of the amino acids varied among stations (k = 0.3-3.1 h-1) with a systematic decrease when going from labile to more refractory …

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Spatial Variation Of Total Co2 And Total Alkalinity In The Northern Indian Ocean: A Novel Approach For The Quantification Of Anthropogenic Co2 In Seawater, C. Goyet, C. Coatanoan, G. Eischeid, T. Amaoka, K. Okuda, R. Healy, S. Tsunogai Jan 1999

Spatial Variation Of Total Co2 And Total Alkalinity In The Northern Indian Ocean: A Novel Approach For The Quantification Of Anthropogenic Co2 In Seawater, C. Goyet, C. Coatanoan, G. Eischeid, T. Amaoka, K. Okuda, R. Healy, S. Tsunogai

Journal of Marine Research

As part of a cooperative effort of the Joint Global Ocean Flux Study (JGOFS) and of the World Ocean Circulation Experiment (WOCE) program, we have measured total CO2 (TCO2) and total alkalinity (TA) along three sections in the northern Indian Ocean. One section through the Gulf of Aden to the Arabian Sea is parallel to the coast of Yemen. One section is across the Arabian Sea along the nominal 9N latitude and the other section is across the Bay of Bengal along the nominal 10N latitude. The measurements were performed on board R/V Knorr in September-October 1995. …

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Some Historical, Theoretical And Applied Aspects Of Quantitative Water Mass Analysis, Matthias Tomczak Jan 1999

Some Historical, Theoretical And Applied Aspects Of Quantitative Water Mass Analysis, Matthias Tomczak

Journal of Marine Research

The concept of water masses is reviewed from the point of view of quantitative water mass analysis. A theoretical framework is presented which describes the life history of water masses in terms of formation, consolidation, aging and decay. Water masses are described as physical entities and compared with their atmospheric counterparts (air masses). The classical temperature-salinity diagram is expanded into the mathematical concept of water types in an n-dimensional parameter space. Water types and their standard deviations are introduced as the foundation for quantitative water mass analysis. The relationship between parameter space and physical space is established through the …

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Modeling The Antarctic Circumpolar Current: A Comparison Of Fram And Equivalent Barotropic Model Results, V. O. Ivchenko, A. E. Krupitsky, V. M. Kamenkovich, N. C. Wells Jan 1999

Modeling The Antarctic Circumpolar Current: A Comparison Of Fram And Equivalent Barotropic Model Results, V. O. Ivchenko, A. E. Krupitsky, V. M. Kamenkovich, N. C. Wells

Journal of Marine Research

Analyzing the FRAM simulations, Killworth (1992) noticed a strong tendency for self-similarity in the vertical structure of the velocity field of the Antarctic Circumpolar Current (ACC). By assuming the self-similarity as a hypothesis, Krupitsky et al. (1996) developed an equivalent barotropic (EB) model of the ACC capable of describing the horizontal structure of the ACC. Compared to the multi-level-primitive-equation GCM, the EB model appeared substantially simpler and therefore useful in pilot process-oriented and sensitivity studies. In the present study dynamical and kinematical comparisons of the EB and FRAM outputs are given.

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Formation And Circulation Of The Water Masses Between The Southern Indian Ocean And Antarctica: Results From Δ18o, Michael P. Meredith, Karen J. Heywood, Russell D. Frew, Paul F. Dennis Jan 1999

Formation And Circulation Of The Water Masses Between The Southern Indian Ocean And Antarctica: Results From Δ18o, Michael P. Meredith, Karen J. Heywood, Russell D. Frew, Paul F. Dennis

Journal of Marine Research

We present measurements of the stable isotopes of oxygen (18O and 16O) from seawater samples collected during the Antarctic Deep Outflow Experiment (ADOX) cruises in the Southern Ocean and southern Indian Ocean, February to March, 1993 and 1994. The data are used in conjunction with hydrographic data to infer characteristics of the formation and circulation of water masses found in the region. The waters on the continental shelf of Antarctica (adjacent to the Princess Elizabeth Trough; PET) are isotopically the lightest found due to the injection of about 1% of glacial meltwater, and are probably advected to …

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On The Chaotic Evolution Of Baroclinic Instability Of Wave-Wave Interactions With Topography, John Kroll Jan 1999

On The Chaotic Evolution Of Baroclinic Instability Of Wave-Wave Interactions With Topography, John Kroll

Journal of Marine Research

De Szoeke (1986) developed an asymptotic solution for the nonlinear evolution of a type of baroclinic instability of a two-layer quasi-geostrophic model over topography. He found that under certain conditions pairs of hybrid modes interacting with topography could become unstable in the linearized model. He also found that the addition of the nonlinearity stabilized the flow which he analyzed using an expansion in small ε, a measure of the topographic height. This work is extended and modified by first considering a slightly varying mean flow (time dependent parametric forcing) which produces chaotic behavior, and then considering friction which allows chaos …

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