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Issues In Stochastic Ocean Modeling, Cecile Penland, Antonio Navarra
Issues In Stochastic Ocean Modeling, Cecile Penland, Antonio Navarra
Journal of Marine Research
The general theory of stochastic differential equations is presented in this chapter, including the theoretical background on how measured statistics from time series can be used to develop a stochastic parameterization. The general rules of stochastic calculus, including the important and often overlooked differences between Ito and Stratonovich calculus, are mentioned, and references are provided in which more detail may be found. We discuss how Stratonovich calculus is usually appropriate for fluid systems, whereas Ito calculus is often appropriate for data assimilation. We also discuss some common numerical pitfalls awaiting the unwary modeler, and warn against unsophisticated random number generators. …
Advanced Wave Modeling, Including Wave-Current Interaction, Alexander V. Babanin, Andre Van Der Weshuijsen, Dmitry Chalikov, W. Erick Rogers
Advanced Wave Modeling, Including Wave-Current Interaction, Alexander V. Babanin, Andre Van Der Weshuijsen, Dmitry Chalikov, W. Erick Rogers
Journal of Marine Research
The paper outlines principles of phase-resolving and phase-average wave models, with emphasis on the state of the art of wave-current interaction physics. We argue that these interactions are the least well-developed part of such models. Linear and nonlinear dynamics of waves on currents are discussed; depth-integrated and depth-varying approaches are described. Finally, examples of numerical model performance for waves on currents in realistic oceanic scenarios are presented.
Tidal Prediction, Gary D. Egbert, Richard D. Ray
Tidal Prediction, Gary D. Egbert, Richard D. Ray
Journal of Marine Research
Tides are the most predictable of oceanographic phenomena, due both to the simplicity and predictability of the astronomical forcing and to the near linearity of the ocean's dynamical response. In the classical and simplest scenario, tidal prediction is based on harmonic analysis of past measurements at a fixed location. Limits to predictability arise because isolated astronomical spectral lines are broadened into "cusps" of incoherent energy, for example through interactions with non-tidal flows. Tidal prediction at locations without past measurements has historically been a major challenge, but, owing to near-global observations of modern satellite altimeters, the empirical harmonic approach now yields …
Modeling And Forecasting Ocean Acoustic Conditions, Timothy F. Duda
Modeling And Forecasting Ocean Acoustic Conditions, Timothy F. Duda
Journal of Marine Research
Modeling acoustic conditions in an oceanic environment is a multiple-step process. The environmental conditions (features) in the area first must be measured or estimated; relevant features include seabed geometry, seabed composition, and four-dimensionally (4D) variable sound-speed and density variations related to evolving or wave motions. Often the dynamical wave modeling depends on first obtaining correct seabed and mean stratification conditions (for example, nonlinear internal wave modeling). Next, this information must be included in sound propagation modeling. A selection of the many methods and tools available for these tasks are described, with a focus on modeling sounds of 20 to 1000 …
Aabw-Transport Variation And Its Effect On Internal Wave Motions Between Top And Bottom Of The Puerto Rico Trench, Hans Van Haren
Aabw-Transport Variation And Its Effect On Internal Wave Motions Between Top And Bottom Of The Puerto Rico Trench, Hans Van Haren
Journal of Marine Research
Slow subinertial variations in Antarctic Bottom Water (AABW) are investigated interacting with internal waves and associated turbulent mixing in the Puerto Rico Trench (PRT), northwest Atlantic. Just below the PRT's top at 5,500 m, a deep-sea mooring was deployed for 14 months. Around 6,100 m, the line held a 200 m long string of 101 high-resolution temperature sensors and a current meter. Around 8,250 m, a similar string held 102 sensors, of which the lowest was 9 m above the bottom. As was measured with shipborne conductivity-temperature-depth profiling down to 7,150 m, PRT waters are very weakly stratified, with local …
Measurement And Modeling Of Volume Scattering Functions For Phytoplankton From Norwegian Coastal Waters, Endre Marken, Nicolausi Ssebiyonga, Jon K. Lotsberg, Jakob J. Stamnes, Børge Hamre, Øyvind Frette, Arne Skodvin Kristoffersen, Svein Rune Erga
Measurement And Modeling Of Volume Scattering Functions For Phytoplankton From Norwegian Coastal Waters, Endre Marken, Nicolausi Ssebiyonga, Jon K. Lotsberg, Jakob J. Stamnes, Børge Hamre, Øyvind Frette, Arne Skodvin Kristoffersen, Svein Rune Erga
Journal of Marine Research
The volume scattering function (VSF) describes the angular distribution of scattered light, and the VSF of phytoplankton is one of the most important inherent optical properties of oceanic water. Despite its importance, relatively few measurements of the VSF have been carried out in aquatic environments, and we present here data and analyses of measured VSFs at 442, 490, and 550 nm for 15 representative phytoplankton species from Norwegian coastal waters. In addition, the analytic scattering phase functions Henyey-Greenstein (HG) and Fournier-Forand, as well as Mie theory, were fitted and compared to the measured VSFs. The measured VSFs for all the …
Numerical Modelling In A Multiscale Ocean, Dale B. Haidvogel, Enrique N. Curchitser, Sergey Danilov, Baylor Fox-Kemper
Numerical Modelling In A Multiscale Ocean, Dale B. Haidvogel, Enrique N. Curchitser, Sergey Danilov, Baylor Fox-Kemper
Journal of Marine Research
Systematic improvement in ocean modelling and prediction systems over the past several decades has resulted from several concurrent factors. The first of these has been a sustained increase in computational power, as summarized in Moore's Law, without which much of this recent progress would not have been possible. Despite the limits imposed by existing computer hardware, however, significant accruals in system performance over the years have been achieved through novel innovations in system software, specifically the equations used to represent the temporal evolution of the oceanic state as well as the numerical solution procedures employed to solve them. …
Coupled Ice-Ocean Modeling And Predictions, Laurent Bertino, Marika M. Holland
Coupled Ice-Ocean Modeling And Predictions, Laurent Bertino, Marika M. Holland
Journal of Marine Research
We review the coupled ice-ocean modeling activities aimed at predictions, both in the near term (days to a week) and in the long term (seasonal to decadal) of the polar oceans. First the state of the knowledge of potential predictability is exposed, then an overview is given of the tools available for carrying out such predictions: the observations that can be used to initialize actual predictions, the coupled ice-ocean–modeling, including the fully-coupled Earth System Models for long-term predictions, and data-assimilation techniques. Finally, the performance of existing prediction systems is reviewed, showing that, although more predictive capability remains than what is …
Data Assimilation For Initialization Of Seasonal Forecasts, Magdalena A. Balmaseda
Data Assimilation For Initialization Of Seasonal Forecasts, Magdalena A. Balmaseda
Journal of Marine Research
This article reviews the requirements for a data assimilation system from the perspective of initializing seasonal forecasts. It provides a historical perspective of the developments in ocean data assimilation and ocean observing systems. It also discusses the differences between state estimation and initialization, and presents a brief assessment of different initialization strategies. The value of assimilating ocean data to estimate the ocean state and to initialize seasonal forecasts is demonstrated. However, it is also shown that the assumption of unbiased models in conventional data assimilation methods is not suitable for the production of long temporal records of ocean initial states. …
Effects Of Small-Scale Turbulence On Phytoplankton Growth And Metabolism, Wilton Gray Burns
Effects Of Small-Scale Turbulence On Phytoplankton Growth And Metabolism, Wilton Gray Burns
Master's Theses and Capstones
Our current understanding of how turbulence affects small planktonic organisms is based on fluid dynamic theory, ocean models, and laboratory experiments that often have conflicting results. Atmospheric models predict that global temperature rise associated with climate change will affect turbulence patterns within the marine photic zone, where phytoplankton reside. To investigate how small-scale turbulence affects growth (growth rates, cell counts and extracted chlorophyll, and nutrient quotas) and metabolism (production of transparent exopolymer particles (TEP)) of marine primary producers, phytoplankton in monoculture and natural assemblages were incubated under a range of turbulent treatments. Results indicate that early in exponential growth of …
Variation In Organismic Rna And Dna Content: Analysis And Application To The Assessment Of Living Planktonic Biomass, Elizabeth Lam Gagneron
Variation In Organismic Rna And Dna Content: Analysis And Application To The Assessment Of Living Planktonic Biomass, Elizabeth Lam Gagneron
Master's Theses
Modern analysis of DNA and RNA nucleic acid sequences has yielded profound changes in our understanding of the genetic biodiversity of planktonic organisms within the microbial food web of aquatic ecosystems. However, the bulk environmental concentrations of DNA and RNA, and their relative ratios, also potentially provide important information on the biomass and metabolic activity of planktonic organisms. Currently, there is a need to quantify the relative living biomass levels of natural water contained in ships’ ballast tanks to regulate the spread of aquatic invasive species (AIS) resulting from ballast water discharge practices within the international shipping industry. Ultraviolet (UV) …
Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment (Inbox): Part 1.Specifications And Chronology Of The S1-Inbox Floats, Ryuichiro Inoue, Toshio Suga, Shinya Kouketsu, Toshiyuki Kita, Shigeki Hosoda, Taiyo Kobayashi, Kanako Sato, Hiroyuki Nakajima, Takeshi Kawano
Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment (Inbox): Part 1.Specifications And Chronology Of The S1-Inbox Floats, Ryuichiro Inoue, Toshio Suga, Shinya Kouketsu, Toshiyuki Kita, Shigeki Hosoda, Taiyo Kobayashi, Kanako Sato, Hiroyuki Nakajima, Takeshi Kawano
Journal of Marine Research
An interdisciplinary project called the Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment (INBOX) has been conducted since 2011. In the oligotrophic subtropics south of the Kuroshio Extension near biogeochemical mooring S1 (30° N, 145° E), 18 floats, each with a dissolved oxygen sensor, have been deployed in a 150 × 150 km square area. With the horizontal (30 km) and temporal (2 days) resolution of the data, we observed an upper ocean structure associated with mesoscale eddies and ocean responses to atmospheric forcing. The data set obtained from the S1-INBOX study was used to elucidate the impacts of physical …
Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment (Inbox): Part 3. Mesoscale Variability Of Dissolved Oxygen Concentrations Observed By Multiple Floats During S1-Inbox, Shinya Kouketsu, Ryuichiro Inoue, Toshio Suga
Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment (Inbox): Part 3. Mesoscale Variability Of Dissolved Oxygen Concentrations Observed By Multiple Floats During S1-Inbox, Shinya Kouketsu, Ryuichiro Inoue, Toshio Suga
Journal of Marine Research
As part of the interdisciplinary project S1-INBOX (Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment conducted around the S1 biogeochemical mooring site), we used data from more than 18 floats and a biogeochemical mooring S1 (near 30° N, 145° E) to investigate temporal and spatial changes in the shallow oxygen maximum (SOM) associated with a mesoscale cyclonic eddy. On the northern edge of the cyclonic eddy, patches (linear dimensions of 20–40 km) with relatively high oxygen concentrations were observed around the SOM. The patterns of the oxygen concentrations reflected the fact that changes of the depths of the isopycnal surfaces …
Baroclinic Instability Over Topography: Unstable At Any Wave Number, Joseph Pedlosky
Baroclinic Instability Over Topography: Unstable At Any Wave Number, Joseph Pedlosky
Journal of Marine Research
The instability of an inviscid, baroclinic vertically sheared current of uniform potential vorticity, flowing along a uniform topographic slope, becomes linearly unstable at all wave numbers if the flow is in the direction of propagation of topographic waves. The parameter region of instability in the plane of scaled topographic slope versus wave number then extends to arbitrarily large wave numbers at large slopes. The weakly nonlinear treatment of the problem reveals the existence of a nonlinear enhancement of the instability close to one of the two boundaries of this parametrically narrow unstable region. Because the domain of instability becomes exponentially …
Carbon Cycling In Santa Barbara Basin Sediments: A Modeling Study, David J. Burdige, Tomoko Komada, Cédric Magen, Jeffrey P. Chanton
Carbon Cycling In Santa Barbara Basin Sediments: A Modeling Study, David J. Burdige, Tomoko Komada, Cédric Magen, Jeffrey P. Chanton
Journal of Marine Research
The primary input of organic matter to almost all marine sediments comes from deposition at the sediment surface. However, in many continental margin settings, reduced carbon can also be added to sediments from below—for example, from “deep” geologic hydrocarbon reservoirs derived from ancient source rocks or from the decomposition of deeply buried gas hydrate deposits. To examine the impact of these two differing reduced carbon inputs on sediment biogeochemistry, a modified reaction-transport model for anoxic marine sediments is described here and applied to data from sediment cores in Santa Barbara Basin to a depth of 4.6 m. Excellent model fits …
Mechanisms Controlling Vertical Variability Of Subsurface Chlorophyll Maxima In A Mode-Water Eddy, Qian P. Li, Dennis A. Hansell
Mechanisms Controlling Vertical Variability Of Subsurface Chlorophyll Maxima In A Mode-Water Eddy, Qian P. Li, Dennis A. Hansell
Journal of Marine Research
An intense subsurface chlorophyll enhancement was found repeatedly within the core of a mode-water eddy during a 2-month period. Two controls on chlorophyll concentrations in this deep chlorophyll maximum (DCM) layer are noted: chlorophyll concentration is controlled by nutrients at low nutrient concentrations and by light when nutrients are saturating. To synthesize these results, a simple one-dimensional nutrient-phytoplankton model is developed by including the effects of phytoplankton self-shading for light attenuation, depth-dependent phytoplankton specific loss, and density-associated nutrient fluctuation in the deep layer. The model is parameterized using eddy data including not only vertical diffusivity, sinking velocity, and chlorophyll-to-carbon ratios, …
Convective Mixing By Internal Waves In The Puerto Rico Trench, Hans Van Haren, Louis Gostiaux
Convective Mixing By Internal Waves In The Puerto Rico Trench, Hans Van Haren, Louis Gostiaux
Journal of Marine Research
A 2.4 km long deep-sea mooring was deployed for 14 months in the Puerto Rico Trench, the deepest part of the Atlantic Ocean. Below its top buoyancy package, the mooring line held a 200 m long string of high-resolution temperature sensors and a current meter. Over the instrumented range between 6,004 and 6,204 m, waters are very weakly stratified, with local buoyancy frequency equaling about 1.9 times the semidiurnal tidal frequency. Besides quiescent waters, the detailed observations show regular vertical turbulent overturning associated with periodic warming and driven by internal tidal and inertial waves. During such episodes, the 4-day and …
Methane Dynamics In Santa Barbara Basin (Usa) Sediments As Examined With A Reaction-Transport Model, David J. Burdige, Tomoko Komada, Cédric Magen, Jeffrey P. Chanton
Methane Dynamics In Santa Barbara Basin (Usa) Sediments As Examined With A Reaction-Transport Model, David J. Burdige, Tomoko Komada, Cédric Magen, Jeffrey P. Chanton
Journal of Marine Research
Here we describe a new reaction-transport model that quantitatively examines δ13C profiles of pore-water methane and dissolved inorganic carbon (DIC) (δ13CCH4 and δ13CDIC) in the anoxic sediments of the Santa Barbara Basin (California Borderland region). Best-fit solutions of the model to these data suggest that CO2 reduction is the predominant form of methanogenesis in these sediments. These solutions also accurately reproduce the isotope depth profiles, including a broad minimum in the δ13CDIC profile and a much sharper (angular) minimum in the δ13CCH4 profile, both …
Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment (Inbox): Part 2. Biogeochemical Responses To Eddies And Typhoons Revealed From The S1 Mooring And Shipboard Measurements, Ryuichiro Inoue, Makio C. Honda, Tetsuichi Fujiki, Kazuhiko Matsumoto, Shinya Kouketsu, Toshio Suga, Toshiro Saino
Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment (Inbox): Part 2. Biogeochemical Responses To Eddies And Typhoons Revealed From The S1 Mooring And Shipboard Measurements, Ryuichiro Inoue, Makio C. Honda, Tetsuichi Fujiki, Kazuhiko Matsumoto, Shinya Kouketsu, Toshio Suga, Toshiro Saino
Journal of Marine Research
An interdisciplinary project called S1-INBOX (Western North Pacific Integrated PhysicalBiogeochemical Ocean Observation Experiment conducted around the S1 biogeochemical mooring site) was carried out during the summer of 2011 in the oligotrophic, subtropical North Pacific Ocean near biogeochemical mooring S1 (30° N, 145° E). Results from the S1 mooring during S1-INBOX revealed a large export flux at a depth of 200 m, a high chlorophyll a concentration in the deep chlorophyll maximum layer, and a high potential photochemical efficiency of photosystem II. These phenomena were associated with vertical uplift of isopycnal surfaces at the edge of a cyclonic eddy and a …
Residual Water Transport In The Marsdiep Tidal Inlet Inferred From Observations And A Numerical Model, Maximiliano G. Sassi, Theo Gerkema, Matias Duran-Matute, Janine J. Nauw
Residual Water Transport In The Marsdiep Tidal Inlet Inferred From Observations And A Numerical Model, Maximiliano G. Sassi, Theo Gerkema, Matias Duran-Matute, Janine J. Nauw
Journal of Marine Research
At tidal inlets, large amounts of water are exchanged with the adjacent sea during the tidal cycle. The residual flows, the net effect of ebb and flood, are generally small compared with the gross flux; they vary in magnitude and sign from one tidal period to the other; and their long-term mean varies from year to year. Here, we focus on the temporal variability of the residual flows in the Marsdiep tidal inlet, which is the western-most inlet of the Wadden Sea, a tidal lagoon along the coasts of the Netherlands, Germany, and Denmark. We compare the transport from a …
The Effect Of Wind Direction On Cross-Shelf Transport On An Initially Stratified Inner Shelf, Rachel M. Horwitz, Steven J. Lentz
The Effect Of Wind Direction On Cross-Shelf Transport On An Initially Stratified Inner Shelf, Rachel M. Horwitz, Steven J. Lentz
Journal of Marine Research
Cross-shelf and along-shelf wind stresses both independently have been shown to drive transport across the inner shelf. We investigate how the circulation and density fields respond to simultaneous cross- and along-shelf wind forcing using a set of model experiments on an initially stratified inner shelf. For all wind directions with a downwelling along-shelf component, the inner shelf is unstratified and the cross-shelf wind dominates transport. For wind directions with an upwelling along-shelf component, the inner shelf can be stratified and the transition from inner to midshelf occurs over a wide swath of shelf. In this transition region, the effects of …
Vorticity Dynamics Near Sharp Topographic Features, Bruno Deremble, William K. Dewar, Eric P. Chassignet
Vorticity Dynamics Near Sharp Topographic Features, Bruno Deremble, William K. Dewar, Eric P. Chassignet
Journal of Marine Research
In ocean models, the interaction with boundaries is often parameterized as it involves small-scale processes that are usually hard to capture in a large-scale model. However, such interactions can play important roles in the model dynamics. For example, the choice of boundary conditions (free-slip vs. no-slip) has a direct impact on the vorticity (enstrophy) budget: with no-slip boundary conditions, vorticity is injected into the system, whereas with free-slip boundary conditions, there should be no vorticity injection as long as the coastline is smooth. However, we show here that at boundary singularities (e.g., corners), vorticity is injected into the domain even …
Wind-Driven Flow Over Topography, Michael A. Spall
Wind-Driven Flow Over Topography, Michael A. Spall
Journal of Marine Research
The space and time scales over which wind forcing can directly drive flows over regions of closed topographic contours are explored using an idealized numerical model and theory. It is shown that stratification limits the vertical scale of the mean flow but also results in an enhanced recirculation strength in shallow water by distorting the isopycnals in the bottom boundary layer. Time-dependent forcing can drive flows that extend deeper than the mean flow because the initial response is primarily barotropic. This response is limited at low frequencies by baroclinic Rossby wave propagation. It is expected that these wind-driven flows might …
A Composite Vertical Current Spectrum For Strongly And Weakly Stratified Seas And Oceans, Hans Van Haren
A Composite Vertical Current Spectrum For Strongly And Weakly Stratified Seas And Oceans, Hans Van Haren
Journal of Marine Research
An overall frequency (σ) spectrum φw(σ, N, fh) is composed for vertical current (w) observations from ocean areas with different stratifications represented by large, 100 m scale buoyancy frequency N. The horizontal Coriolis parameter is denoted by fh. In the open Atlantic Ocean, the relatively strong horizontal layering in density supports the φw that is found in semiequilibrium under the degradation of the lowest internal wave mode. This φw is not constant with frequency; however, its variance increases between σ = f and its peak near σ = (0.5 …
Species Diversity Patterns Of Marine Plankton And Benthos In Chinese Bays: Baseline Prior To Large-Scale Development, Weiwei Yu, Bin Chen, Paolo F. Ricci, Luoping Zhang, Jianguo Du, Zhiyuan Ma
Species Diversity Patterns Of Marine Plankton And Benthos In Chinese Bays: Baseline Prior To Large-Scale Development, Weiwei Yu, Bin Chen, Paolo F. Ricci, Luoping Zhang, Jianguo Du, Zhiyuan Ma
Journal of Marine Research
More than 28,000 marine species have been recorded in China, which accounts for approximately 10% of all marine organisms in the world and plays a potentially important role in protecting global marine biodiversity. However, knowledge of marine biodiversity patterns in China is limited, and in particular, no comparative diversity analysis has been carried out for Chinese bays. In this study, national-scale species diversity patterns of coastal bays were examined on the basis of investigations for approximately 81 bays throughout the entire Chinese coastline in the 1980s and the early 1990s, revealing the baseline of diversity patterns prior to large-scale development. …
Intertidal Percolation Through Beach Sands As A Source Of 224,223 Ra To Long Island Sound, New York, And Connecticut, United States, Henry Bokuniewicz, J. Kirk Cochran, Jordi Garcia-Orellana, Valenti Rodellas, John Wallace Daniel, Christina Heilbrun
Intertidal Percolation Through Beach Sands As A Source Of 224,223 Ra To Long Island Sound, New York, And Connecticut, United States, Henry Bokuniewicz, J. Kirk Cochran, Jordi Garcia-Orellana, Valenti Rodellas, John Wallace Daniel, Christina Heilbrun
Journal of Marine Research
Along tidal coasts, seawater circulated through the intertidal beach contributes to submarine groundwater discharge (SGD) and its associated geochemical signature. The short-lived radium isotopes, 223Ra (half-life = 11.4 d) and 224Ra (half-life = 3.66 d), were used to quantify this component of SGD in a large estuary, Long Island Sound (LIS), New York, United States. The tide is semidiurnal with a range of approximately 2 m. Concentrations in beach pore waters ranged from 97 to 678 disintegrations per minute (dpm) 224Ra 100 L–1, whereas concentrations in open coastal waters ranged from approximately 12 to 69 …
Nitrogen Substrate–Dependent Nitrous Oxide Cycling In Salt Marsh Sediments, Qixing Ji, Andrew R. Babbin, Xuefeng Peng, Jennifer L. Bowen, Bess B. Ward
Nitrogen Substrate–Dependent Nitrous Oxide Cycling In Salt Marsh Sediments, Qixing Ji, Andrew R. Babbin, Xuefeng Peng, Jennifer L. Bowen, Bess B. Ward
Journal of Marine Research
Nitrous oxide (N2O) is important to Earth's climate because it is a strong absorber of radiation and an important ozone depletion agent. Increasing anthropogenic nitrogen input into the marine environment, especially to coastal waters, has led to increasing N2O emissions. Identifying the nitrogen compounds that serve as substrates for N2O production in coastal waters reveals important pathways and helps us understand their control by environmental factors. In this study, sediments were collected from a long-term fertilization site in Great Sippewissett Marsh, Falmouth, Massachusetts. The 15N tracer incubation time course experiments were conducted and …
Distinguishing Turbulent Overturns In High-Sampling-Rate Moored Thermistor String Observations, Hans Van Haren, Louis Gostiaux
Distinguishing Turbulent Overturns In High-Sampling-Rate Moored Thermistor String Observations, Hans Van Haren, Louis Gostiaux
Journal of Marine Research
Turbulent overturns are distinguished from salinity-compensated intrusions in high-resolution moored thermistor string observations. The buoyancy frequency N is used to make the time dimensionless, "t*." This results in a primary, visual means to easily compare the duration of overturns with N, the natural frequency that separates internal waves from turbulent overturns. As a secondary means, the shapes of overturns are investigated. Above various sloping topography between 500 and 1,000 m water depth where the buoyancy period varies between ∼1,300 and 2,600 s, vertical overturns of ∼40 m last Δt* =0.2–0.4. This corresponds with the timescale …
Spiciness, Trevor J. Mcdougall, Oliver A. Krzysik
Spiciness, Trevor J. Mcdougall, Oliver A. Krzysik
Journal of Marine Research
We define and present algorithms for spiciness, which is an oceanographic variable whose isopycnal variations reflect isopycnal water-mass contrasts in density units. Discussion of spiciness in the oceanographic literature has often concentrated on its supposed orthogonality to isopycnals on the salinity-temperature diagram and how this orthogonal nature means that spiciness is a “passive” thermodynamic variable. Here we show that this “orthogonal” property is devoid of physical meaning. Moreover, it is emphasized that the notion of “orthogonality” on the salinity-temperature diagram does not give rise to a passive thermodynamic variable. Rather, the passive nature of variations of any thermodynamic variable is …
The Influence Of Anoxia And Substrate Availability On N2o Cycling By Denitrification In The Upper Boundary Of The Oxygen Minimum Zone Off Northern Chile, Maribeb Castro-González, Laura Farías
The Influence Of Anoxia And Substrate Availability On N2o Cycling By Denitrification In The Upper Boundary Of The Oxygen Minimum Zone Off Northern Chile, Maribeb Castro-González, Laura Farías
Journal of Marine Research
Strong accumulations of N2O at oxyclines are some of the most conspicuous features of the world's oceans. However, the origin of these maxima, and the relative contribution of nitrification and denitrification in N2O cycling, remains unclear. In order to gain insight into the importance of denitrification and factors regulating N2O cycling at upper oxyclines in the eastern South Pacific, the production and consumption of N2O by denitrification were measured using a classical acetylene method under induced anoxia with the addition of an electron acceptor (nitrite) and donors (sodium acetate and glucose). The …