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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

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

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) (δ¹³C_CH4 and δ¹³C_DIC) 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 δ¹³C_DIC profile and a much sharper (angular) minimum in the δ¹³C_CH4 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

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

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

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

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

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 …

“I Take--No Less Than Skies”: Emily Dickinson And Nineteenth-Century Meteorology, Kjerstin Evans Ballard

Theses and Dissertations

Emily Dickinson's poetry functions where scientific attention to the physical world and abstract theorizing about the ineffable intersect. Critics who emphasize the poet's dedication to the scientific often take for granted how deeply the uncertainty that underlies all of Dickinson's poetry opposes scientific discussion of the day. Meteorology is an exceptional nineteenth-century science because it takes as its subject complex systems which are inexplicable in Newtonian terms. As such, meteorology can articulate the ways that Dickinson bridges the divide between the unknown and the known, particularly as she relates to the interplay of nature and culture, the role of careful …

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 φ_w(σ, N, f_h) 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 f_h. In the open Atlantic Ocean, the relatively strong horizontal layering in density supports the φ_w that is found in semiequilibrium under the degradation of the lowest internal wave mode. This φ_w 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

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

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

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

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 …

Satellite Based Assessment Of Hydroclimatic Conditions Related To Cholera In Zimbabwe, Antarpreet Jutia, Haidar Aldaach, Hannah Billian, Ali Akanda, Anwar Huq, Rita Colwell

Faculty & Staff Scholarship

Introduction

Cholera, an infectious diarrheal disease, has been shown to be associated with large scale hydroclimatic processes. The sudden and sporadic occurrence of epidemic cholera is linked with high mortality rates, in part, due to uncertainty in timing and location of outbreaks. Improved understanding of the relationship between pathogenic abundance and climatic processes allows prediction of disease outbreak to be an achievable goal. In this study, we show association of large scale hydroclimatic processes with the cholera epidemic in Zimbabwe reported to have begun in Chitungwiza, a city in Mashonaland East province, in August, 2008.

Principal Findings

Climatic factors in …

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

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 …

Low-Frequency Variability Of The Separated Western Boundary Current In Response To A Seasonal Wind Stress In A 2.5-Layer Model With Outcropping, Jérôme Sirven, Sabine Férvrier, Christophe Herbaut

Journal of Marine Research

The response of the separated western boundary current to a seasonally varying wind stress is studied in a 2.5-layer model where the second layer outcrops. The model is eddy permitting with a resolution of one-sixth of a degree, and the geometry of the basin is idealized. The response is studied for two mean states: the first one is only wind driven, whereas the second one takes into account the existence of a meridional overturning circulation. The separation latitude and the mean path followed by the separated western boundary current are shifted northward of approximately 2° when the overturning circulation is …

The Wall-Layer Dynamics In A Weakly Stratified Tidal Bottom Boundary Layer, I. Lozovatsky, S. U. P. Jinadasa, H. J. S. Fernando, J.-H. Lee, Chang Su Hong

Journal of Marine Research

The application of the classical logarithmic layer model for wall-bounded shear flows to marine bottom boundary layer (BBL) usually leads to an overestimation of the friction velocity u_* due possibly to the influence of form drag, stratification, and rotation of the flow vector. To gain insights on the BBL velocity scaling, acoustic Doppler current profiler (ADCP) measurements taken in the East China Sea were analyzed (a total of 270 sixteen-minute averaged velocity profiles). Single and double log-layer models, a log-wake model, and a modified log-layer (MLL) model that accounts for stratification in the upper part of the BBL (Perlin, …

Sandy Sediment Budget Of The Midcoast Of Rio Grande Do Sul, Brazil, Lucas Marchi De Motta, Elírio Ernestino Toldo Jr., Luiz Emílio De Sá Brito De Ameida, José Carlos Nunes

Journal of Marine Research

Calculation of the coastal sediment budget involves estimation of the timing and intensity of processes of erosion, transport, and deposition, as well as an understanding of local and regional sediment dynamics. The modern sedimentary deposits present in the coastal zone constitute the physical basis of coastal ecosystems. Knowledge of the dynamics of these sediments from the source to sink area, through regional sediment management, is critical to understanding the long-term stability of the coastal zone and the fate of these important natural resources. In this article, the littoral cell concept has been applied to the midcoast of Rio Grande do …

Water Masses And Nutrient Sources To The Gulf Of Maine, David W. Townsend, Neal R. Pettigrew, Maura A. Thomas, Mark G. Neary, Dennis J. Mcgillicuddy Jr., James O'Donnell

Journal of Marine Research

The Gulf of Maine, a semienclosed basin on the continental shelf of the northwest Atlantic Ocean, is fed by surface and deep water flows from outside the gulf: Scotian Shelf Water (SSW) from the Nova Scotian shelf that enters the gulf at the surface and slope water that enters at depth and along the bottom through the Northeast Channel. There are two distinct types of slope water, Labrador Slope Water (LSW) and Warm Slope Water (WSW); it is these deep water masses that are the major source of dissolved inorganic nutrients to the gulf. It has been known for some …

Ecosystem-Scale Rainfall Manipulation In A Piñon-Juniper Forest At The Sevilleta National Wildlife Refuge, New Mexico: Meteorological Data (2006-2013), William Pockman, Nathan Mcdowell

Sevilleta LTER Program Data

Climate models predict that water limited regions around the world will become drier and warmer in the near future, including southwestern North America. We developed a large-scale experimental system that allows testing of the ecosystem impacts of precipitation changes. Four treatments were applied to 1600 m2 plots (40 m × 40 m), each with three replicates in a piñon pine (Pinus edulis) and juniper (Juniper monosperma) ecosystem. These species have extensive root systems, requiring large-scale manipulation to effectively alter soil water availability. Treatments consisted of: 1) irrigation plots that receive supplemental water additions, 2) drought plots that receive 55% of …

Applications Of Satellite Remote Sensing In The Environment, Rajee Olaganathan, Muhammad Ihsan Bin Ibrahim, Huang Meitong, Tan Yong Jie Shawn, Wilson Tok Wei Sheng, Et Al.

Publications

Since its inception, satellite remote sensing has enabled observations of environmental changes at inaccessible locations in meteorology, disaster control, oceanography, agriculture, glaciology, geology etc. Using the information gathered from satellite remote sensing, changes in the physical environment can be measured and the information are utilized to predict future patterns and achieve better environmental outcomes in different areas. This paper serves to highlight some of the areas in which satellite remote sensing has been applied. In meteorology, Earth’s solar radiation intensity, geothermal energy and wind velocity are measured by satellite remote sensing. Satellite imageries are also used for forecasting natural disasters …

Diffuse Reflectance Of Foams, M. A. Devetzoglou, J. R. G. Evans

Journal of Marine Research

There have been few studies of the optical properties of foams but the results of these investigations are of particular relevance to current discussions about climate restoration by means of oceanic foam because they indicate the influence of foam raft number on albedo. The diffuse reflectance of foams prepared from eight surfactants was measured in a 0°/45° geometry with a collimated, solar simulation light source and a photodiode by reference to barium sulphate white standards. Reflectance, or albedo, in the range of 0.5 to 0.59 was recorded for foams prepared with sodium dodecyl sulphate (SDS), methyl cellulose, and TWEEN 20 …

Some Influences Of Remote Topography On Western Boundary Currents, Michael A. Spall

Journal of Marine Research

The influence of topography in a basin interior on the separation and time-dependence of strongly nonlinear western boundary currents is explored using a shallow water numerical model and scaling theory. In the linear limit, the western boundary current follows the western boundary to the latitude of the gap in the interior topography where it then separates from the coast and flows eastward in a narrow jet. As nonlinearity is increased, the flow initially remains steady but develops a series of stationary meanders extending off the western boundary at the separation latitude. For strongly nonlinear flows the solutions become time-dependent. The …

Symmetric Instability Of Cross-Stream Varying Currents, Joseph Pedlosky

Journal of Marine Research

The symmetric instability of a simple shear flow in which the velocity is a linear function of the vertical coordinate but which varies slowly in the cross-stream direction is studied using an asymptotic analytical method. Explicit analytical solutions are found for the evolution of the envelope of the developing linear instability. Although the problem with no lateral variation yields cell-like instabilities growing in place, the lateral variation of the shear produces time dependence and cross-stream propagation of the envelope and accompanying cells. A similar solution is derived for the case of laterally uniform shear in a current whose depth slowly …

Available Energy Of The World Ocean, Peter R. Bannon, Raymond G. Najjar

Journal of Marine Research

The available energy of the ocean is the excess of the sum of the ocean's internal and gravitational energies with respect to its equilibrium state, which is in thermodynamic equilibrium and has the same total entropy as the ocean. The equilibrium state for the world ocean is rigorously determined to be an isothermal ocean with a temperature of 3.66˚C and a horizontally uniform absolute salinity that increases monotonically from 27.30 g kg^–1 at the surface to 47.39 g kg^–1 at a depth of 5.5 km. This salinity profile is consistent with a uniform relative chemical potential of 47.44 …

Anatomy Of A Langmuir Supercell Event, A. E. Gargett, D. K. Savidge, J. R. Wells

Journal of Marine Research

Langmuir supercells (LS), which are Langmuir circulations (LC) extending over full water column depth during storms and revealed by high water column backscatter from surface-origin microbubbles and bottom-origin sediment, were discovered in 2003 during several months of measurements in 15 m of water near the coast of New Jersey. Both the structures themselves and the specific forcing conditions under which they occur have been documented elsewhere. This paper provides an account of the broader oceanographic setting of supercell events, focusing on conditions at the start and end. The start of events is associated with the presence of surface waves of …

A Comparison Of Transport And Position Between The Gulf Stream East Of Cape Hatteras And The Florida Current, A. Sanchez-Franks, C. N. Flagg, T. Rossby

Journal of Marine Research

The Florida Current (FC) transport and Gulf Stream (GS) transport and position have been measured almost continuously for many decades in the Florida Straits at ∼27° N and for the last 20 years at ∼38° N along the Oleander line, respectively. Variations in both currents have been linked to the North Atlantic Oscillation (NAO). Here we show five different proxies for the position of the GS near the Oleander line and find all five measures internally consistent. Further, using a zonally averaged index, the local measurements prove to be good representatives of overall meridional shifting of the current (between Cape …

Effects Of Injury And Nutrition On Sediment Reworking By Clymenella Torquata (Annelida: Polychaeta), Beth R. Campbell, Sara M. Lindsay

Journal of Marine Research

Marine infaunas influence sediment chemistry, nutrient cycling, and microbial communities as they burrow, feed, defecate, and irrigate their tubes and burrows. Nonlethal tissue loss to predators or other disturbances is frequently observed in macrofaunal communities, and previous research has reported significant effects of onetime injury on animal activity. In this study, we examined the effects of injury and nutrient enrichment on sediment reworking rates of a common deposit-feeding polychaete, Clymenella torquata. Individual worms in cores were monitored in a recirculating seawater system, and their defecation and sediment mixing monitored under several experimental conditions. Worms held in control (unenriched) sediment …