Digital Commons Network^™

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 …

Responsible, Renewable, And Redesigned: How The Renewable Energy Movement Can Make Peace With The Endangered Species Act, Kalyani Robbins

Faculty Publications

One of the most promising routes to a sustainable energy future, as well as climate change mitigation, is the development of renewable energy sources such as wind, solar energy, and hydropower. Indeed, scientists have proposed plans to move completely (100 percent!) to these energy sources within a couple of decades. Mark Z. Jacobson and M.A. Delucchi, scientists from Stanford and U.C. Davis, have outlined a plan to achieve this goal, thereby “eliminating all fossil fuels”. Hydroelectric power already provides almost one-fifth of the world's electricity, and wind and solar development is rapidly picking up as well. However, before we leave …

Mixing By Microorganisms In Stratified Fluids, Gregory L. Wagner, William R. Young, Eric Lauga

Journal of Marine Research

We examine the vertical mixing induced by the swimming of microorganisms at low Reynolds and Péclet numbers in a stably stratified ocean, and show that the global contribution of oceanic microswimmers to vertical mixing is negligible. We propose two approaches to estimating the mixing efficiency, η, or the ratio of the rate of potential energy creation to the total rate-of-working on the ocean by microswimmers. The first is based on scaling arguments and estimates η in terms of the ratio between the typical organism size, a, and an intrinsic length scale for the stratified flow, l = (νκ/N …

The Relation Between Unstable Shear Layer Thicknesses And Turbulence Lengthscales, Eric Kunze

Journal of Marine Research

This note explores the connection between the (i) lengthscales of unstable finescale shear layers which are responsible for turbulence production, (ii) turbulence patch thicknesses and (iii) the outer scales of turbulence, that is, the density overturn (Thorpe) and Ozmidov lengthscales, in the stratified ocean interior. Explanations are offered both for why (i) turbulence patches are often observed to be much thicker than outer turbulence scales and (ii) there is a spectral gap between finescale internal waves and the outer scales of turbulence. A finescale parameterization based on unstable shear predicts Ozmidov lengthscales smaller than unstable-shear-layer thicknesses for moderately unstable gradient …

Refraction Of Swell By Surface Currents, Basile Gallet, William R. Young

Journal of Marine Research

Using recordings of swell from pitch-and-roll buoys, we have reproduced the classic observations of long-range surface wave propagation originally made by Munk et al. (1963) using a triangular array of bottom pressure measurements. In the modern data, the direction of the incoming swell fluctuates by about ± 10° on a time scale of one hour. But if the incoming direction is averaged over the duration of an event then, in contrast with the observations by Munk et al. (1963), the sources inferred by great-circle backtracking are most often in good agreement with the location of large storms on weather maps …

Influence Of Mean Circulation On Large-Scale Decadal Basin Modes, Dhouha Ferjani, Thierry Huck, Alain Colin De Verdière

Journal of Marine Research

The effect of large-scale mean circulation on the generic property of intrinsic basin modes of decadal variability is investigated through linear stability analysis of a two-layer shallow water model over a flat- and a variable-bottom topography. The mean circulation is forced through either surface wind stress or vertical velocities at the layers interface representing surface heat flux. Regardless of the type of forcing, the large-scale mean circulation reduces the damping of the decadal basin modes. The wind forcing mostly affects the mode damping, by up to 30% for a climatological amplitude, whereas the heat flux forcing mostly increases the oscillation …

Diatom Control Of The Autotrophic Community And Particle Export In The Eastern Bering Sea During The Recent Cold Years (2008–2010), Matthew S. Baumann, S. Bradley Moran, Michael W. Lomas, Roger P. Kelly, Douglas W. Bell, Jeffrey W. Krause

Journal of Marine Research

The southeastern Bering Sea has exhibited shifts in climate since the start of the 21st century. The regional climate shifts are manifested in the duration and areal extent of seasonal sea-ice coverage. During a recent cold period (2008–2010) with extensive spring sea-ice cover over the southeastern shelf of the Bering Sea, a total of 77 water column and 24 sediment trap profiles were collected over the shelf and shelf break and analyzed for autotrophic pigment concentrations and elemental (carbon, nitrogen, phosphorus, and silicon) concentrations in suspended and exported particulate material. These results are used to establish the seasonal succession of …

The Transport Of Nutrient-Rich Indian Ocean Water Through The Red Sea And Into Coastal Reef Systems, James H. Churchill, Amy S. Bower, Daniel C. Mccorkle, Yasser Abualnaja

Journal of Marine Research

Driven by upwelling-favorable monsoon winds, nutrient-rich Gulf of Aden Intermediate Water (GAIW) enters the Red Sea from the Indian Ocean each summer. Hydrographic and velocity data acquired in autumn 2011 provide the first indication that GAIW is carried rapidly northward along the eastern Red Sea margin in a well-defined subsurface current with speeds >30 cm s^–1. The nutrient-rich (NO₂ + NO₃ concentrations up to 17 μmol l^–1) GAIW overlaps the euphotic zone and appears to fuel enhanced productivity over depths of 35–67 m. GAIW is broadly distributed through the Red Sea, extending northward along …

Group Behavior Among Model Bacteria Influences Particulate Carbon Remineralization Depths, K. A. S. Mislan, Charles A. Stock, John P. Dunne, Jorge L. Sarmiento

Journal of Marine Research

Organic particles sinking from the sunlit surface are oases of food for heterotrophic bacteria living in the deep ocean. Particle-attached bacteria need to solubilize particles, so they produce exoenzymes that cleave bonds to make molecules small enough to be transported through bacterial cell walls. Releasing exoenzymes, which have an energetic cost, to the external environment is risky because there is no guarantee that products of exoenzyme activity, called hydrolysate, will diffuse to the particle-attached bacterium that produced the exoenzymes. Strategies used by particle-attached bacteria to counteract diffusive losses of exoenzymes and hydrolysate are investigated in a water column model. We …

Simple Models For The Heat Flux From The Atlantic Meridional Overturning Cell To The Atmosphere, M. Behl, D. Nof, S. Van Gorder

Journal of Marine Research

It has been suggested that a slowdown of the Atlantic meridional overturning cell (AMOC) would cause the Northern Hemisphere to cool by a few degrees. We use a sequence of simple analytical models to show that due to the nonlinearity of the system, the simplified heat flux from the modeled AMOC to the atmosphere above is so robust that even changes of as much as 50% in the present AMOC transport are not enough to significantly change the temperature of the outgoing warmed atmosphere (i.e., the fraction of the atmosphere warmed by the AMOC). Our most realistic model (which is …

Thermohaline Staircases In The Western Mediterranean Sea, Harry L. Bryden, Katrin Schroeder, Stefania Sparnocchia, Mireno Borghini, Anna Vetrano

Journal of Marine Research

Thermohaline staircase structures are commonly observed in the western Mediterranean Sea within the halocline-thermocline connecting the Levantine Intermediate Water at about 400 m depth with the western Mediterranean deep waters below 1,500 m. In this halocline-thermocline where warmer, saltier waters overlie colder, fresher deep waters, salt finger mixing processes are thought to be active and produce staircases with layers of order 75 m thickness containing nearly constant properties separated by sharp steps of order 6 m thickness with jumps in properties between the layers. While the layers have nearly constant salinity, potential temperature, and potential density, each property decreases very …

A Constraint On The Thickness-Weighted Average Equation Of Motion Deduced From Energetics, Kunihiro Aoki

Journal of Marine Research

This study reviews the system governed by the thickness-weighted average (TWA) equation of motion, considering energetics. It is known that the TWA equation of motion based on the primitive equation describes the fluid motion with the residual mean velocity defined as the TWA velocity and is written in the same form as the nondissipative primitive equation, except that the eddy momentum fluxes (the interfacial form stress and Reynolds flux associated with eddy motion) are embedded in this equation. Also, incompressibility and density (buoyancy) conservation in the adiabatic condition hold in this system. In this study, considering that the TWA system …

On The Structure And Distribution Of Thin Anticyclonic Lenses In The Southeast Pacific Ocean, T. Rossby

Journal of Marine Research

The velocity structure of an anticyclonic lens in the southeast Pacific centered at 300–400 m depth was scanned in detail with a 75 kHz acoustic Doppler current profiler on the RV Atlantis during a February 2010 transit along 20° S. Embedded in the main thermocline with a vertical span of ∼500 m, the lens had an overall diameter of ∼150 km with a peak speed of 0.33 m s^–1 at ∼35 km radius. Knowledge of the velocity field permitted determination of energetics and vorticity properties in detail. The ratio of potential to kinetic energy was ∼14, and the relative …

A Wind Tunnel Study Of The Effect Of Adjacent Buildings On Near-Field Pollutant Dispersion From Rooftop Emissions, Ted Stathopoulos, Bodhisatta Hajra, Mauricio Chavez, Ali Bahloul

Rapports de recherche scientifique

Cliquez ici pour la version française de ce rapport

La dispersion des polluants des émissions de cheminées de toit dans la couche limite est fortement influencée par la présence de bâtiments avoisinants et la topographie locale. Il est donc très difficile d’évaluer précisément les concentrations dans le panache sur différentes surfaces de bâtiments. Les polluants émis par une cheminée de toit peuvent présenter des risques pour la santé des occupants des bâtiments s’ils se réintroduisent dans le bâtiment duquel ils émanent ou s’ils pénètrent dans un bâtiment voisin par des ouvertures se trouvant sur différentes surfaces de bâtiments. La plupart …

Wind Energy Opposition In Vermont: Perspectives On The State's Energy Future, William R. Pitkin Iv

Pomona Senior Theses

Due to its high levels of concern and awareness of environmental issues, rural character, and sparse population, Vermont would at first glance appear to possess the ideal recipe to become a national leader in renewable energy development. Renewable initiatives have focused primarily on wind energy, as over a dozen wind farms have been proposed in the last few years across the state. However, in spite of the widely held belief in Vermont’s wind energy future, its proponents have run into vehement opposition at every proposed site, often successfully impeding the planned developments.

This report develops a wide-level framework of the …

Increasing Ca2+ Deposition In The Western Us: The Role Of Mineral Aerosols, Janice Brahney, Ashley P. Ballantyne, C. Sievers, Jason C. Neff

Watershed Sciences Faculty Publications

Considerable research has focused on the role of industrial emissions in controlling the acidity of precipitation; however, much less research has focused on the role of mineral aerosols emitted from soils. According to data published by the National Atmospheric Deposition Network (NADP), over the past 17 years Ca2+ deposition has increased over large regions of the US. A trend analysis to determine regions of significant change in Ca2+ deposition revealed statistically significant increases in three broad regions within the western half of the country: the inter-mountain west, the midwest, and the northwest. We evaluated potential changes in sources of calcium …

The Quantifying, Predicting, And Exploiting Uncertainty Program: Exploring Oceanographic Processes In A Complex Bathymetric Shelf/Slope Environment Affected By The Kuroshio, Glen Gawarkiewicz, Sen Jan

Journal of Marine Research

We will describe the multi-disciplinary international program, Quantifying, Predicting and Exploiting Uncertainty, which consisted of observations, modeling and remote sensing studies focused on a region northeast of Taiwan in the East China Sea. We focus on results on the physical oceanographic and biogeochemical processes. Concurrent observations of acoustic propagation also occurred during the intensive observation period. This program was a joint Taiwan-U.S. effort involving four different ships sampling the continental shelf and slope during August-September, 2009. Primary goals of the program included 1) studying the structure and variability of the Cold Dome, a cool cyclonic feature frequently present in summer …

Phytoplankton Abundance And Size-Fractionated Structure In Three Contrasting Periods In The Pear River Estuary, Xia Zhang, Zhen Shi, Xiaoping Huang, Feng Ye, Qingxia Liu

Journal of Marine Research

Phytoplankton abundance, composition and size-fractionated chlorophyll a (micro-, nano- and pico-chl. a) in the Pearl River Estuary (PRE), South China were assessed in three surveys (Aug. 2010, Jan. 2011 and Aug. 2011) to identify key environmental indicators that shape their distribution patterns. Non-metric multidimensional scaling (MDS) showed that the PRE formed three regional clusters that were characterized by a transition from dominant freshwater species to estuarine diatoms in normal summer flow conditions (Aug. 2010). With a reduced river flow in winter (Jan. 2011), the inner estuary was categorized as one group marked by the predominance of the nanoflagellate, Plagioselmis …

Observations Of A Freshwater Pulse Induced By Typhoon Morakot Off The Northern Coast Of Taiwan In August 2009, Sen Jan, Joe Wang, Yiing Jiang Yang, Chin-Chang Hung, Ching-Sheng Chern, Glen Gawarkiewicz, Ren-Chieh Lien, Luca Centurioni, Jia-Yu Kuo, Bee Wang

Journal of Marine Research

In this paper we describe large-scale impacts from a typhoon on the circulation over the continental shelf and slope north of Taiwan. Typhoon Morakot was a category 2 tropical storm that landed in central Taiwan, but caused destruction primarily in southern Taiwan from Aug. 8–10, 2009. The typhoon brought record-breaking rainfall; approximately 3 m accumulated over four days in southern Taiwan. River discharge on the west coast of Taiwan increased rapidly from Aug. 6–7 and peaked on Aug. 8, yielding a total volume 27.2 km³ of freshwater discharged off the west coast of Taiwan over five days (Aug. 6–10). …

Linear Dynamics Of A Stably-Neutrally Stratified Ocean, Gregory M. Reznik

Journal of Marine Research

Linear dynamics of stably-neutrally stratified fluid consisting of the stably stratified upper layer and the homogeneous lower layer is studied with and without rotation. The density and other fields are continuous at the interface between the layers. A special feature of this configuration is existence of the wave mode related to the homogeneous layer. In non-rotating fluid this is the homogeneous layer vortex mode characterized by a stationary three-dimensional velocity field confined to the lower layer. In the presence of rotation, the mode turns into the gyroscopic waves. Besides the mode, the wave spectrum contains internal waves and the zero …

Internal Tides On The East China Sea Continental Slope, Ren-Chieh Lien, Thomas B. Sanford, Sen Jan, Ming-Huei Chang, Barry B. Ma

Journal of Marine Research

Strong semidiurnal internal tides are observed on the continental slope of the East China Sea (ECS) using an array of subsurface moorings and EM-APEX floats. A Princeton Ocean Model (POM) is used to simulate the effects of stratification profiles on the generation and propagation of M₂ internal tides; model simulations are compared with observations. On the ECS continental slope northeast of Taiwan, the semidiurnal barotropic tidal current flows nearly perpendicular to the shelf break and continental slope, favoring the generation of internal tides. Both the critical slope analysis and numerical model results suggest multiple generation sites on the continental …

Influence Of Bottom Topography On Large-Scale Decadal Basin Modes, Dhouha Ferjani, Thierry Huck, Alain Colin De Verdière

Journal of Marine Research

The influence of bottom topography on the generic properties of the baroclinic basin modes is investigated through linear stability analysis of a two-layer shallow water ocean model. Various idealized bottom profiles imitating a mid-ocean ridge and continental slopes are analyzed in an extratropical β-plane closed basin. Only large-scale features are examined, the eddy effects being parametrized as turbulent eddy viscosity that allows the selection of large-scale eigenmodes. At coarse resolution, the largest-scale lowest-frequency baroclinic modes appear as the least damped modes. For scales much larger than the internal deformation radius, the damping rate is relatively independent of dissipation, the mode …

Significant Internal Waves And Internal Tides Measured Northeast Of Taiwan, Timothy F. Duda, Arthur E. Newhall, Glen Gawarkiewicz, Michael J. Caruso, Hans C. Graber, Yiing Jang Yang, Sen Jan

Journal of Marine Research

Internal gravity waves in an area northeast of Taiwan are characterized using data from multiple sensor types. The data set includes intermittent information collected from a ship and short time series from moorings. Modeled nonlinear waves are fitted to observed nonlinear waves to provide self-consistent estimates of multiple wave parameters. A nonlinear internal wave of over 50 m amplitude, observed in deep water, is examined in detail. This wave was moving northward from the southern Okinawa Trough toward the continental shelf, and presumably formed from internal tides propagating northward from the Ilan Ridge area. A possible scenario for the formation …

Corrigendum To “Nutrient Supply In The Southern East China Sea After Typhoon Morakot", Chin-Chang Hung, Chih-Ching Chung, Gwo-Ching Gong, Sen Jan, Yaling Tsai, Kuo-Shu Chen, Wen Chen Chou, Ming-An Lee, Yi Chang, Meng-Hsien Chen, Wen-Rong Yang, Chiung-Jung Tseng, Glen Gawarkiewicz

Journal of Marine Research

The authors regret that some errors occurred in the Figure 6 published with incorrect data in our recent article (Hung et al. 2013: 145). The corrected data are presented in the revised Figure 6 below. The conclusions drawn in the original article are still supported by the revised results, though some estimates have been corrected.

Foam Triangles, S. A. Thorpe

Journal of Marine Research

Foam patches left by waves breaking as they approach a smooth and gently sloping beach from a near-normal direction sometimes have the distinctly triangular shape that has been studied by Turner and Turner (2011). Explanations of the size of the angle at the apex of the triangles observed by Turner and Turner are suggested in terms of physical processes that determine the speed at which the point of breaking travels along a wave crest. These explanations differ from the entrainment model proposed by Turner and Turner (2011). The range of sizes of the apex angles can most likely be explained …

Instability Of An Idealized Tidal Mixing Front: Symmetric Instabilities And Frictional Effects, K. H. Brink, Deepak A. Cherian

Journal of Marine Research

Finite amplitude instability of an idealized tidal mixing front is considered for cases where there is an active symmetric instability during the early stages of evolution. This can happen either when the initial front is sharp, or when a bottom stress leads to a well-mixed bottom boundary layer under the front. In either case, there is an initial phase, several days long, of slantwise convection, after which a much more energetic and spatially distributed baroclinic or barotropic instability dominates. The presence of an initial symmetrically unstable phase has no obvious effect on the subsequent eddy evolution. Bottom friction does lead …

Recycling And Burial Of Phosphorus In Sediments Of An Anoxic Fjord—The By Fjord, Western Sweden, Lena Viktorsson, Mikhail Kononets, Per Roos, Per O. J. Hall

Journal of Marine Research

Recycling and burial of sediment phosphorus were studied in the By Fjord, western Sweden, during the years 2009 to 2010 using autonomous benthic landers and sediment sampling. The By Fjord is a small fjord with a shallow sill at its narrow mouth, which limits water exchange of the fjord's basin water. The water in the basin is exchanged only every 3 to 5 years and the water below sill level is anoxic or sulfidic between water renewals. Five sites were examined in the By Fjord; three shallow sites above the sill level with oxic bottom waters and two deeper sites …

Seasonal, 2-D Sedimentary Extracellular Enzyme Activities And Controlling Processes In Great Peconic Bay, Long Island, Zhenrui Cao, Qingzhi Zhu, Robert C. Aller, Josephine Y. Aller, Stuart Waugh

Journal of Marine Research

Extracellular enzymes (EE) initiate heterotrophic remineralization by hydrolyzing high-molecularweight organic matter to substrates that are sufficiently small (approximately 600 Da) to be transported across cell membranes. An accurate understanding of EE associated remineralization processes in sedimentary deposits requires measuring patterns of extracellular enzyme activity (EEA) with minimal disturbance of natural sediment structure. In this study, two-dimensional patterns of extracellular enzyme (leucine aminopeptidase) activity in shallow-water, marine sediments from Great Peconic Bay, Long Island, New York were examined seasonally at sub-millimeter resolution by using a newly developed EE planar fluorosensor. Comparisons of spatially averaged, vertical enzyme activity profiles measured using this …