<p> The operational ocean wave model needs a sea ice component to simulate the global ocean waves. Current ocean wave models treat ice covered regions crudely. The purpose of this thesis is to provide a unified continuum model for the wave ice interaction. Sea ice is constantly subject to environmental forcing. As a result, its physical appearance and mechanical properties vary dynamically. There are three existing classic wave ice interaction models: viscous layer, mass loading, and thin elastic plate models. Viscous layer models may be used to simulate grease ice, mass loading model is probably suitable for pancake ice, and thin elastic plate model may be used to describe a continuous ice sheet floating in water. This situation means that for different kind of sea ice we need different wave ice interaction models. Recently, a proposed viscoelastic wave ice interaction model synthesized the three classic models into one model. Under suitable limiting conditions this model converges to the three previous models. Based on this new development, the present study expands the viscoelastic model for wave propagation through two connected ice covered ocean regions. By doing so, the complete theoretical framework for evaluating wave propagation through various ice covers may be implemented in the operational ocean wave models. In this thesis, we introduce a three-layer viscoelastic model to include the eddy viscosity in turbulent boundary layer under the ice cover into previous viscoelastic model and the methods to calculate wave reflection and transmission. We also use recent results of a laboratory study to determine the viscoelstic model parameters with an inverse method. The thesis concludes with a numerical procedure for implementing the viscoelastic dispersion relation into the ocean wave model and some ideas of model parameterization. </p>

<p> Langmuir turbulence in the upper ocean is generated by the interaction between the wind-driven shear current and the Stokes drift velocity induced by surface gravity waves. In homogenous (neutrally stratified) shallow water, the largest scales of Langmuir turbulence are characterized by full-depth Langmuir circulation (LC). LC consists of parallel counter-rotating vortices aligned roughly in the direction of the wind. In shallow coastal shelves, LC has been observed engulfing the entire water column, interacting with the boundary layer and serving as an important mechanism for sediment re-suspension. In this research, large-eddy simulations (LES) of Langmuir turbulence with full-depth LC in a wind-driven shear current have revealed deviations from classical log-layer dynamics in the surface and bottom of the water column. For example, mixing due to full-depth LC induces a large wake region eroding the classical bottom (bed) log-law velocity profile. Meanwhile, near the surface, Stokes drift shear serves to intensify small scale eddies leading to enhanced mixing and disruption of the surface velocity log-law. The modified surface and bottom log-layer dynamics induced by Langmuir turbulence and full-depth LC have important implications on Reynolds-averaged Navier-Stokes simulations (RANSS) of the general coastal ocean circulation. Turbulence models in RANSS are typically calibrated under the assumption of log-layer dynamics, which could potentially be invalid during occurrence of Langmuir turbulence and associated full-depth LC. A K-Profile Parameterization (KPP) of the Reynolds shear stress in RANSS is introduced capturing the basic mechanisms by which shallow water Langmuir turbulence and full-depth LC impact the mean flow. Single water column RANS simulations with the new parameterization are presented showing good agreement with LES</p>

This thesis discusses a new stream of research and analysis which will form part of the Northern Watch Technology Demonstration project. The objective of the thesis is to develop and illustrate a procedure for identifying and characterizing combinations of sensors and systems that will provide cost-effective options for Arctic maritime surveillance. A ship detection simulation is constructed, the results of which are used to produce a set of ranked options for combinations of sensors used to conduct maritime surveillance at a strategic choke point located at the Barrow Strait, in Canada's Northwest Passage. The overall objective of the surveillance is to improve on the detection, classification, and identification of maritime vessels. The modeled performance and effectiveness of each sensor is evaluated in relation to the multiple objectives using the Analytical Hierarchy Process (AHP) to rank alternative sensor effectiveness and performance. The results indicate that the most cost-effective solution is to install an Automatic Identification System (AIS) sensor at the Northern Watch station. However, due to practical concerns, alternatives to this approach are presented and discussed.

Ships produce a large amount of oily wastewaters such as bilge water which needs to be treated prior to being discharged. Bilge water is a very challenging wastewater to treat due to large variations in production rates and the complex nature of the wastes in solution. Ever increasing regulations are being imposed on the treatment and release of bilge water to the environment. The objective of this study was to develop a membrane process to remove oil and grease from bilge water to a level where it could be discharged into sensitive environments. This work focused on five elements of study: (1) Evaluation of feasibility and performance of bilge water treatment using a pilot scale microfiltration/ultrafiltration (MF/UF) hybrid membrane system; (2) Development of a pilot scale membrane cascade for selective removal of oil to 0 ppm or a non-detectable level from bilge water while minimizing concentrate production; (3) Establishment of an analytical method to extract and analyze organic species at very low concentration levels for the analysis of oil and grease content found in bilge water and membrane permeate; (4) Investigation of environmentally friendly membrane cleaning methods; and (5) Study of filtration mechanism in the treatment of bilge water using ultrafiltration and microfiltration. Pilot scale membrane cascade systems were designed and tested for the treatment of synthetic bilge water. Experimental results showed that the pretreatment of this oily wastewater using microfiltration, prior to ultrafiltration, is desirable as used oils and particulates can block the feed channels of UF spiral and hollow fiber modules. Backflushing is an effective technique to reduce fouling caused by "sticky" cakes in synthetic bilge water treatment using a microfiltration membrane. Membrane support structure was found to be critical in enhancing flux during backflushing. This work outlined the need for microfiltration membranes offering good particulate clearance to be used in backflushing coalescence applications. A pilot scale membrane hybrid system, consisting of a coalescing backflushed microfiltration membrane used as a pretreatment and an ultrafiltration membrane as a final polishing step, was found to be very effective in this application, producing permeate with oil and grease content well below the allowable discharge limit (15 ppm) for coastal waters. Another membrane cascade system using tubular MF and UF membranes in a first stage and flat sheet UF membranes in a second stage was found to be able to produce water containing below detectable levels of hexane extractable material. Permeates of various molecular weight cut-off (MWCO) membranes from the cascade system were collected and analyzed using an extraction procedure followed by gas chromatography (GC). Analytical results showed that solid phase extraction using ENVI-18 sorbent retained much of the organic matter found in the bilge water and could not preserve the molecular weight distribution in the oil mixture used to prepare synthetic bilge water. n-Hexane liquid-liquid extraction technique was found to be able to preserve the molecular weight distribution of diesel and lubricating oils separated by ultrafiltration. The effect of membrane MWCO in separation of oil and grease was also studied in this work. Environmentally friendly physical membrane cleaning methods, such as backflushing with hot water or steam followed by pressurized air, were found effective in regenerating membrane flux for large pore KOCH carbon membranes in the treatment of synthetic bilge water using a MF/UF hybrid system. The beneficial effects for steam cleaning were found to be evident. Optimal cycle times between physical cleanings were determined. Filtration mechanisms in the treatment of synthetic bilge water were studied using four classical filtration models and a combined model. Experimental results of the research conducted in this study suggested that it is possible to achieve the target of removing oil from bilge water to 0 ppm or non-detectable levels through the proper design of the membrane system, selection of appropriate membranes, determination of optimal operating parameters, and assessment of membrane performance.

No description available.

A coupled 3D atmosphere-ocean model is developed to study the effect of the oceanic mixed layer depth (OMLD) on the intensification and the motion of the tropical cyclones. We first study the baroclinic response of the ocean with uniform and nonuniform initial OMLD to the steady forcing of an axisymmetric TC moving at a prescribed translating speed. Emphases are placed on the TC-ocean interactions in the coupled model simulations. Results from 96-hour integrations show TC that move into deeper (shallower) OMLD regions experience rates of increase (decrease) in their intensities once the OMLD is 10 m deeper (2.5 m shallower) than that of the TC's origin. The rightward bias of the sea surface temperature (SST) response appears in every numerical experiment and the maximum SST cooling is about 1-2$\sp\circ$C, depending on the initial OMLD distribution and the TC's translating speed. Wind induced near inertial oscillation of the mixed layer current and subinertial oscillation of the mixed layer depth are found in the wake of the storm. The TC in the atmosphere-only model tends to displace toward the north further than the TC in the coupled model does. The deviation of the two tracks begins to occur after 36 hours. The maximum difference between the tracks is about 89 km occurring at 93 hours. A good correlation is found between the maximum wind speed and the northward deflection of the TC. Results of this study compare favorably with the statistics of the TC's track in the western North Pacific and the North Atlantic. / Source: Dissertation Abstracts International, Volume: 55-04, Section: B, page: 1480. / Major Professor: Richard L. Pfeffer. / Thesis (Ph.D.)--The Florida State University, 1994.

A method is developed for thermodynamic and kinematic analysis by partitioning boundary layer data by parcel vertical velocity and the conservative forms of temperature and moisture using a Lagrangian parcel approach. Large Eddy Simulation (LES) derived data fields were used to develop the partitioning method. The LES model provides sufficiently dense and thermodynamically consistent data, which are not yet available from observational datasets. LES Model data fields are three velocity components, potential temperature, total water mixing ratio, cloud liquid water, turbulent kinetic energy (TKE), and buoyancy. The procedure calculates vertical mixing, vertical transports, and the joint frequency histograms of the turbulent data fields with respect to potential temperature and total water mixing ratio, with a Lagrangian partitioning into strong rising, strong sinking, and weakly moving subsets. / An analysis of boundary layer thermodynamics using datasets from the large eddy simulation (LES) model is used to test the partitioning and analysis method. Observed datasets from the Frontal Air Sea Interaction Experiment (FASINEX) are used for comparative analysis of marine boundary layers and LES results. Results indicate the method is useful in further understanding the diurnal boundary layer entrainment hysteresis cycle, vertical transport, and similar features which develop from the non-Gaussian properties of turbulent boundary layer data. Potential applications of these results in boundary layer modeling are discussed. / Source: Dissertation Abstracts International, Volume: 55-01, Section: B, page: 0131. / Major Professor: Eric A. Smith. / Thesis (Ph.D.)--The Florida State University, 1993.

It has been estimated that 80% of the organic carbon preserved in marine sediments occurs in 'terrigenous-deltaic' regions near river mouths. The Louisiana coast, which contains the most prolific deltaic regions in the U.S. (Atchafalaya and Mississippi rivers), provides an excellent field laboratory to compare the effects of differential sedimentation rates and redox conditions on organic carbon burial using pigments as biomarkers Application of HPLC/MS has led to identification of high concentrations of bacteriopigments in sediments collected in area with recorded hypoxia on the Louisiana shelf. This confirmed the development of anaerobic photosynthetic community (purple and green sulfur bacteria) over a large deltaic area. Downcore distributions of bacteriopigments in sediments indicated the highest concentrations occurred between 1960 and the present, coinciding with increased nutrient loading from the Mississippi River Four novel decay products, esters of carotenols and chlorins (carotenol chlorins esters, CCEs), were also identified in sediments from the LA shelf. Our laboratory copepod grazing experiment confirmed that similar to sterol chlorin esters (SCEs), CCEs can be produced through zooplankton grazing on diatom, providing excellent class-specific biomarkers of zooplankton grazing on phytoplankton. Pigment inventories indicated that pheophytin-a , pyropheophytin-a, chlorophyllone-a, CCEs and SCEs were major decay products in LA shelf sediments. Absence of the two grazing biomarkers, CCEs and SCEs, in river sediments suggested that grazing activity was minimal in river waters. However, chlorophyllone- a was present in river sediments and its abundance in river sediments was comparable with that in shelf sediments. This suggested that chlorophyllone- a was not closely associated with grazing like CCEs and SCEs. Downcore distribution of pigments, bulk organic carbon and nitrogen, and radioactive isotopes (210Pb, 137Cs, 7Be) suggested that a 9--10 cm surface mixed layer was common for samples collected in areas with low sedimentation. It was observed that pigment decay rate constants in the mixed layer were greater than the accumulation layer by 1--3 orders of magnitude. Decay rates of pigments in the upper mixed layer were variable and primarily dependent upon differences in the inherent lability of pigment compounds and bulk carbon, while in the accumulation layer all pigments decayed at similar rates / acase@tulane.edu

The combustion of high level sulfur-containing (2--5%) fuels generates sulfuric acid in marine diesel engines. In the absence of any control, sulfuric acid attacks metal surfaces and is the prime cause of ring and cylinder bore wear. One of the major requirements of the marine cylinder lubricant (MCL) is therefore their ability to neutralize the sulfuric acid and any other acids formed during the combustion process. The MCL's additives for acid neutralization are basically oil-soluble Group-II basic metal (calcium or magnesium) overbased sulfonates, or phenates. Those overbased detergents are in the form of reverse micelles with a calcium carbonate core, which is stabilized by an outer alkyl/aryl sulfonic acid shell In this study, a capillary video-microscopy technique was used to develop an experimental protocol for ranking the ability of marine cylinder lubricants (MCL's) to neutralize acids. The technique allows the direct observation of an acid droplet from the instant of its formation inside an oil-filled capillary. It was applied to several commercial oils with known rates of acid-neutralization ability as well as model lubricants made in the lab to qualitatively, yet successfully, test this ability. The optical observations allow one to propose a plausible interfacial neutralization mechanism by which the overbased detergent additive system performs the task of acid neutralization. According to this mechanism, the overbased sulfonate reverse micelles are the site for the neutralization reaction, which occurs at the oil-acid interface. The results confirm that the detergent surfactants are chemically bound to the micellar core. In the case of overbased calcium-carbonate detergents reacting with sulfuric acid, the formation of solid crystals was observed which may form a protective antiwear film on engine metal surfaces. By measuring the shrinking rate of nitric-acid drops in MCL, the acid-neutralizing ability of commercial MCL's as well as model lubricants can also be determined quantitatively. The shrinking rate of a nitric-acid drop in MCL was found to be constant during the reaction period and independent of the initial drop size. Analysis of the experimental results, following an interfacial neutralization reaction mechanism, suggests that the 'adsorption' of overbased reverse micelles is the controlling step in the reaction process The effects of two key additional additives---nonionic surfactants and dispersants---to MCL were also investigated. The rate of the neutralization reaction is enhanced by the presence of the nonionic surfactants in the model MCL's and is consistent with the formation of the mixed micelle systems which makes the basic core of the overbased sulfonate more accessible to the aqueous acid due the increased size and flexibility of the overbased sulfonate reverse micelle. Presence of small amounts of dispersants (1 wt.%) decreases the reaction rate for both nitric and sulfuric acid, while further increasing the dispersants, concentration (up to ca. 4%) does not lead to additional reduction of the acid-neutralizing ability. In the case of sulfuric acid, the dispersants act so as to also effectively disperse the hydrated calcium sulfate crystals produced by the neutralization reaction / acase@tulane.edu

Overbased detergents are present in marine cylinder lubricants for neutralizing combustion-generated acids in engine environment. The nature of overbased particles and the mechanisms by which they act determine their success in neutralizing acids and preventing cylinder corrosive wear. Strong-stick and weak-stick collisions are proposed to drive the acid and base transfer in oil media. The acid neutralization by overbased detergents can be a crystal-growing reaction or a crystal-solubilized reaction. With the protection of overbased particles, cylinder corrosive wear possibly occurs under conditions that facilitate a crystal-solubilized reaction, and the Ostwald ripening of acid droplets may be a decisive cause of corrosive wear. Temperature impacts on the rate of acid neutralization dramatically, while the size of an acid droplet does not affect its neutralization rate initially until the droplet shrunk to a certain level Acid neutralization experiments were carried out inside a heating-capillary, which can simulate high-temperature conditions (from ambient temperature to oil boiling point), and the progress of neutralization was recorded in real time through a video-microscope. The heating capillary microreactor was specially prepared to be electrically conductive by coating with tin-doped indium oxide and to remain transparent so that optical microscopy can be conducted inside it; when a current passes, the coated capillary could generate desired temperatures at very fast rates (75-198&deg;C/s) In this research, the inconsistencies between 'dynamic structure' and 'rigid structure,' between 'acid-to-base' transfer and 'base-to-acid' transfer, and among the formation of acid-neutralization products, may be reconciled. It has been demonstrated that the Ostwald ripening of acid droplets works against the MCL-acid neutralization. New strategies to improve overbased detergents, marine cylinder lubricants, and engine designs may include (i) facilitating crystal-growing reactions and (ii) mitigating acid-Ostwald ripening / acase@tulane.edu