Oceanography and Atmospheric Sciences and Meteorology Commons^™

A Global Internal Tide Modeling Framework For Improving Satellite Observations Of Fine-Scale Ocean Circulation, Badarvada Yadidya, Brian K. Arbic, Edward D. Zaron, Jay F. Shriver, Maarten C. Buijsman, Eric P. Chassignet, Loren Carrère, Michel Tchilibou

Faculty Publications

Small-scale oceanic eddies and filaments mediate the vertical exchange of heat and carbon within the global ocean. The Surface Water and Ocean Topography (SWOT) mission resolves these features through wide-swath interferometry, but internal tides often mask these observations. Non–phase-locked internal tides present special difficulty because they vary with the evolving ocean background. We show that this chaotic variability can be predicted. We use a data-assimilative ocean forecast model to resolve the mesoscale environment and separate tidal signals from the broader circulation. The model captures the organized structure of these incoherent waves in the independent SWOT measurements. Correcting for the total …

Backscattering By Particles Of Sizes <0.2 Μm In Seawater, Xiaodong Zhang, Yuanheng Xiong

Faculty Publications

We measured the angular scattering functions at 517 nm in different size fractions, including bulk and very small particles (VSP for diameters <0.2 μm), in a variety of waters ranging from coasts to open oceans and from surface to depths as deep as 3,000 m. The measurements revealed a strong covariation in backscattering between VSP and bulk particle populations. The fractional contribution by VSP decreases from 60% in clear oceanic water where bulk particle backscattering coefficient bbp is on the order of 0.001 m⁻¹ to <2% in turbid coastal water where bbp ∼0.1 m⁻¹. An empirical model is developed (r² = 0.89) to estimate bbp for VSP from the bulk bbp, which can now be routinely obtained from satellite observations.

Modeling The Effects Of Low-Pressure Atmospheric Fronts On Sediment Transport Through Mississippi Sound Barrier Island Inlets, Nicholas J. Gagliano

Master's Theses

Coastal sediment dynamics in the Mississippi Sound are strongly influenced by tropical cyclones and the more frequent passage of low-pressure atmospheric fronts. While hurricanes are well recognized for reshaping barrier islands and altering sediment budgets, the cumulative role of recurrent fronts remains poorly quantified. This thesis investigates the impacts of six low-pressure atmospheric fronts (2015–2017) on sediment flux through six barrier island inlets in the Mississippi Sound.

A high-resolution application of the Regional Ocean Modeling System with the Community Sediment Transport Modeling System was developed to simulate tidal circulation, wind-driven currents, and sediment dynamics. Waves were excluded from the simulations. …

An Assessment Of The Deep And Coastal Responses To Hurricane Passage In The Gulf Of Mexico, Using Complementary Observational Records And Model Simulations, Senam Kofi Tsei

Dissertations

In this dissertation, I examine and discuss different ocean features and ocean processes essential to the intensification of tropical cyclones in the Gulf of Mexico, drawing on observations, theory, and numerical model analyses across both the deep ocean and continental shelf-regimes. In the deep ocean, I integrate in situ measurements, theoretical framework, a 1D shear driven mixed layer model, and a high resolution model outputs to evaluate how salinity-driven stratification, Loop Current warm core eddies, pre-existing warm mixed layer temperatures, and the governing mechanisms mixed layer adjustment shape the upper ocean response before, during, and after storm passage. In the …

News Briefs, Marvin H. Jeter Iii, Joyce Shaw

Mississippi Libraries

News updates from Gunter Library at the Gulf Coast Research Laboratory and from the Mississippi Library Commission.

Hydrodynamic Tipping Points In The Mississippi Sound In Response To Bonnet Carré Spillway Openings, Mustafa Kemal Cambazoglu, Brandy N. Armstrong, Mohsena Lopa, Marc Diard, Jerry D. Wiggert

Faculty Publications

This project examines the current operational strategy of the Bonnet Carré Spillway (BCS), a Mississippi River flood-control structure located about 21 miles northwest of New Orleans, Louisiana, and managed by the U.S. Army Corps of Engineers. The BCS is part of the larger Mississippi River and Tributaries Project, a network of levees and control structures designed to minimize flooding from the American plains to southern Louisiana. The spillway is opened when river discharge at New Orleans is forecasted to exceed 1,250,000 cubic feet per second, diverting significant volumes of Mississippi River water into Lake Pontchartrain which subsequently flows into Mississippi …

The Critical Role Of Near-Surface Dynamics In Identifying Spawning Areas Of Atlantic Bluefin Tuna In The Gulf Of Mexico, Donald R. Johnson, William J. Teague, Harriet Perry, James S. Franks

Gulf and Caribbean Research

Atlantic Bluefin Tuna, Thunnus thynnus (ABFT), migrate long distances to broadcast spawn in the Gulf of Mexico (GOM) basin, the Mediterranean Sea and the Slope Sea (NW Atlantic). These areas have commonalities including a highly dynamic upper ocean eddy environment that draws nutrients from shallow thermoclines and adjacent continental shelves and can provide temporal sanctuaries from some larval predators. In the GOM basin, the Loop Current (LC) and its energetic spin—off eddies sweep weak swimming predators such as jellyfish (Pelagia noctiluca) into lines and aggregations, leaving relatively open areas as temporal sanctuaries for ABFT larvae during the vulnerable …

Isolation Of The 2019 Bonnet Carré Spillway Effects On The Habitat Suitability Of Brown Shrimp (Farfantepenaeus Aztecus) And Blue Crab (Callinectes Sapidus) Using A Modeling Approach, Mallory Dyson

Master's Theses

In 2019, an unprecedented flood year, the Bonnet Carré Spillway (BCS) was opened on two separate occasions (February 27^th to April 11^th, and May 10^th through July 27^th) diverting a volume 6 times the volume of Lake Pontchartrain into the surrounding coastal waters of Louisiana, Mississippi, and Alabama. The goal of this research was to determine the spatio-temporal influence of these freshwater releases on two economically and ecologically important species (Farfantepenaeus aztecus and Callinectes sapidus) with variable responses to salinity and temperature depending on the age class. The Habitat Suitability Index (HSI) …

An Investigation Of Paleoclimate Through A Sedimentological Lens In The Gulf Of Mexico And Western North Pacific, Sarah Monica

Dissertations

This dissertation explores the use of sediment cores as proxy data for the reconstruction of paleoclimatic and environmental conditions. Human-caused climate change is leading to dramatic shifts in the global climate. As the instrumental record of climate is relatively short compared to the amount of time Earth has experienced weather, this work aims to extend our knowledge of climate beyond the instrumental record, thereby improving our holistic understanding of the climate system. In Chapter one, sediment cores from the central Texas inner shelf are used to produce a record of intense tropical cyclone (TC) activity over a ~4500-year period. X-Ray …

Assessment Of Estuarine Respiration And Benthic Nutrient Fluxes In Mississippi Sound, Nur Pasha Sufian

Master's Theses

This study quantified seasonal and spatial variability of both water column and benthic respiration rates as well as benthic nutrient fluxes along the Mississippi Sound. Respiration was measured in recirculating incubation chambers using Firesting optical DO sensors (PyroScience GmbH), and changes in nutrient concentrations were assessed. Mean water column respiration rates ranged from 0.35 and 2.76 µM O₂ hr⁻¹, with the lowest rates in the winter and the highest in the summer while detectable nutrient concentrations (ammonium, (NH₄⁺), and soluble reactive phosphate (PO₄³⁻)) showed only slight decreases (< 1 µM) over all seasons. Sediment incubation chambers consistently had much greater oxygen declines than the water incubations and showed seasonal trends with the highest mean respiration rates measured in the summer and the lowest mean in the winter, with a range from 107.4 to 1514.9 µmol O₂ m⁻² hr⁻¹ (2.6 to 36.3 mmol O₂ m⁻² d⁻¹). Sediment incubations consistently showed increases in NH₄⁺ concentrations in the overlying water, resulting in calculated NH₄⁺ benthic flux rates of 0.73 to 379.01 µM N m⁻² hr⁻¹ with the lowest rates in the winter and highest rates in the summer. Although PO₄³⁻ concentrations were often below detection in cooler seasons, PO₄³⁻ flux also peaked during the summer (< 28.8 µmol P m⁻² hr⁻¹). In this study, temperature was a key regulator for estuarine respiration and benthic nutrient flux rates, and these rates were positively correlated with porewater nutrient concentrations and sedimentary organic matter. These findings illustrate that benthic respiration can contribute to water column hypoxia and that sediments serve as a source of nutrients to the water column. Overall, these findings provide us with valuable insight about the seasonal coupling of oxygen demand and nutrient flux in the Mississippi Sound and provide valuable baseline data for future biogeochemical modelling of hypoxia, eutrophication, and productivity.

Enhanced Point Cloud Generation From A Novel 360° Underwater Lidar, Olagoke E. Daramola

Dissertations

This dissertation presents novel algorithms to improve the mapping capabilities of a 360-degree underwater Pulsed Laser Line Scanner LiDAR (PLLS-360°). Due to its 360° field-of-view (FOV), the PLLS-360° is a compact full-waveform omnidirectional imager suitable for seafloor mapping, underwater asset inspection, object detection, ice-sheet mapping, and construction progress monitoring. The proposed methodology includes an improved waveform fitting technique for saturated waveform recovery, detection array response correction, radiometric corrections, and fusion of LiDAR and sonar bathymetric datasets. The first part of this dissertation assesses the LiDAR’s performance and describes how the data for this unique 360° FOV architecture is processed. The …

Simulating Interactions Between (Remote) Internal Waves And The Background Flows And Topography Of The U.S. West Coast, Oladeji Siyanbola

Dissertations

This dissertation focuses on the simulation of remotely and locally generated semidiurnal internal tides (ITs) and near-inertial waves (NIWs), and how they interact with the California Current System (CCS) and the U.S. West Coast (USWC) topography. In Chapter II, we force Regional Ocean Modeling System (ROMS) simulations of the CCS with tides and remote internal waves (IWs) originating from as far as Hawaii, using a realistic global HYbrid Coordinate Ocean Model (HYCOM) simulation. To allow for optimal wave energy influx and minimize boundary reflections from the interior of the domain, we conduct boundary sensitivity tests on tide and IW forcing …

Investigating Nekton Response To Changing Salinities In The Mississippi Sound: An Experimental And Statistical Approach, Adam Murray

Master's Theses

The Mississippi Sound provides nursery habitats for many coastal species and is recognized for its commercial fisheries. Previous freshening events linked to the Bonnet Carré Spillway, a Mississippi River flood diversion structure, proved catastrophic for oyster populations in the Mississippi Sound, but effects on mobile fish and shellfish species are not well-defined. The planned Mid-Breton Sediment Diversion (MBSD), an initiative to combat wetland loss, is also forecasted to lower salinities in the region, increasing the need to better understand responses of commercially and ecologically important species to freshening events. The objective of this study was to characterize effects of salinity …

Modeling Hourly Storm Surges Using Deep Learning Techniques, Md Abu Zafor

Master's Theses

Storm surges cause coastal flooding, one of the most devastating coastal hazards. Accurate modeling of storm surges is essential for predicting and mitigating these impacts. Traditional approaches model surges at individual tide gauges and often focus on daily time scales, leading to data redundancy and limiting their ability to capture sub-daily variability. This study addresses these limitations using deep learning (DL) algorithms to model hourly surges simultaneously at multiple tide gauges along the U.S. East Coast and Gulf of Mexico. Three algorithms, Convolutional Neural Network (CNN), Long Short-Term Memory (LSTM), and a hybrid ConvLSTM are employed to model surges using …

Sedimentary Characteristics Of Flood Deposits In Coastal And Fluvial Environments: Examples From Washover Fans (North Carolina, Usa) And Floodplain Deposits (Mississippi, Usa), Shara Gremillion

Dissertations

Extreme flooding from severe and prolonged meteorological events and / or overbanking rivers are some of the most deadly and expensive disasters globally, impacting millions of lives, the environment, and property. People living in vulnerable areas, such as near coasts and rivers, are the first to be impacted with effects of these flood hazards. Scientific studies and their results can aid communities and officials in planning and preparing for those flood impacts. In this three-part study, flood impacts from coastal storms in North Carolina, and flooding along the Mississippi River (MSR) in the state of Mississippi, USA are assessed from …

Understanding The Variability Of Circulation And Water Quality At Experimental Oyster Leases In The Mississippi Sound Using A High-Resolution Nested Modeling Approach, Shihab Hossain Saran

Master's Theses

Four 50-acre experimental oyster leases; two near Saint Louis Bay (StLB) and two near Pascagoula Bay (PB) were recommended to provide science-based guidance for oyster reef restoration efforts in response to continued limited productivity of oysters in the Mississippi Sound (MSS). Two-way nested simulations using ROMS within COAWST modeling framework have been run with improved forcings to analyze circulation, salinity and temperature variability within and around the lease areas under the extreme freshwater inflow from Bonnet Carré Spillway (BCS) openings and local rivers in 2019. High-resolution atmospheric forcing data is crucial because diurnal sea-land breeze affects salinity variability by increasing …

Projected Range Shift Of The Atlantic Surfclam, Spisula Solidissima, And The Ocean Quahog, Arctica Islandica, Under Climate-Induced Benthic Warming: Forecasting Fishery Influence In The Mid-Atlantic Bight Throughout The 21st Century, Molly Mae Spencer

Master's Theses

The Atlantic surfclam, Spisula solidissima, and ocean quahog, Arctica islandica, are biomass dominant bivalve species on the eastern North American continental shelf, both supporting lucrative commercial fisheries in the Mid-Atlantic with a combined value of $53.6 million in ex-vessel revenue per year. Rapid climate change is expected to modify the geographic range of these bivalve populations across the Mid-Atlantic Bight (MAB), suggesting transformative consequences for the surfclam fishery. This study forecasted future distributions of the two species from years 2016 – 2095, based on projected bottom water temperatures and a temperature-dependent population dynamics model, to project subsequent fishery-based indicators …

Observations Of Lateral Salinity Variability At A Deltaic-Bay Transition Zone, Mobile Bay, Alabama, Clara Oxford, Brian Dzwonkowski, Josh Goff

Gulf and Caribbean Research

No abstract provided.

Variability In Semidiurnal Surface And Internal Tides In Global Ocean Model Simulations, Harpreet Kaur

Dissertations

This dissertation focuses on semidiurnal (D2) surface and internal tides. Chapter 2 investigates the transition of M₂ barotropic Kelvin waves into Hybrid Kelvin-Edge (HKE) waves and the associated generation of internal tides at widening shelves using theory and a realistic global baroclinic Hybrid Coordinate Ocean Model (HYCOM) simulation. To understand the effect of complex, realistic bathymetry on the HKE wave transition, we perform quasi-realistic barotropic HYCOM simulations of the Celtic Sea/Bay of Biscay shelf areas. We conclude that the HKE wave transition is most likely masked by the effects of complex bathymetry and offshelf baroclinic fluxes cannot be exclusively …

Biophysical Factors Affecting Habitat Suitability For Crassostrea Virginica, Jason D. Tilley

Dissertations

Oyster reefs provide a variety of important ecosystem services. However, the mortality rate of eastern oyster, Crassostrea virginica, the dominant species that produces oyster reefs in the northern Gulf of Mexico, is increasing at an alarming rate due to a variety of abiotic and biological factors. I examined how biophysical factors, including the less-studied fatty acid profiles of the suspended particulate matter on which oysters feed, influenced morphometric condition of C. virginica.

I sampled suspended particulate matter (SPM) and oysters in-situ in the western Mississippi Sound, which historically supported the majority of oyster production in Mississippi waters. Sampling …

Estimation Of Angular Response Curves Using A Phase Differencing Bathymetric Sonar, Kandice Gunning

Master's Theses

Although Multibeam Echosounders (MBES) backscatter products like Angular Response Curves (ARC) and mosaics have been used and applied to different sediment types as classification tools, little is known about the extraction and interpretation of ARCs using Phase Differencing Bathymetric Sonar Systems (PDBS). This thesis aims to use an across-track approach to develop a method for extracting ARCs from georeferenced bathymetric data using PDBS.

Three different data collection surveys were conducted using a PDBS operating at 540kHz. Using only the bathymetric data, initial ARCs from 3 different intensity classes (high, medium, and low) were successfully extracted, the results of which attempted …

Understanding The Flow Dynamics Of The Pearl River, Ms, Through Hydrodynamic Modeling, Nahruma Mehzabeen Pieu

Master's Theses

The Pearl River brings fresh water and nutrients into Lake Borgne regulating conditions for oyster growth in estuarine waters. However, there are no flow measurement stations installed on East Pearl or West Pearl either at the river outlets or after the upstream bifurcation of the Pearl. This study aims to model the Lower Pearl River to understand the flow dynamics in the major branches, and to determine the final outflow distribution into the Mississippi Sound, aiming to improve river forcing for ocean models studying estuarine dynamics of the Mississippi Sound.

Synthetic meandering bathymetry with updated banks is developed and applied …

Estimation Of Quantitative Genetic Parameters Of The Eastern Oyster (Crassostrea Virginica) In The Gulf Of Mexico, Heather King

Master's Theses

The decline of natural oyster reefs in Gulf of Mexico (Gulf) states has stimulated the development of aquaculture to support the industry and restoration programs. Gulf habitats feature diverse salinity environments that may require oysters bred for habitat-specific optimal genetic characteristics. In this work, genetic parameters for performance in habitats with different salinity were estimated. In September 2020, 102 males and 102 females sourced from 17 natural reefs across the northern Gulf were bred according to 2 males x 2 females non-overlapping factorial crossing designs, resulting in 204 full and half sibs. All families were pooled after fertilization according to …

Assessing Dynamics And Trends Of Co2 Flux On The Louisiana Shelf, Claire Mcguire

Master's Theses

The Gulf of Mexico on an annual timescale acts as a sink for ­CO₂. Previous studies have investigated regional-scale trends in the Gulf based on model output. In our investigation of the northern Gulf of Mexico, and especially the area surrounding the Louisiana delta, we found different trends compared with previous studies of the open ocean Gulf and broader shelf region. Predictions of global patterns of the ocean CO₂ cycle require regional studies of unique areas like the Louisiana Shelf. The Louisiana Shelf is a shallow system, has input from river systems, experiences seasonal hypoxia, and is …

The Mobility Of Long-Lived Radioisotopes And Their Burial In The Marine Environment, Neil Redmond

Dissertations

Marine sediments record chemical signals that reflect past environmental conditions. It is important to establish how these signals are created and whether they may be altered over time so that they can be useful for reconstructing ocean history. Measurements of uranium isotopes are used as a novel proxy for sedimentary diagenetic processes (Chapter 2). Because ²³⁴U can be ejected from mineral lattice during the decay of ²³⁸U, it creates a pool of U in porewater that is potentially mobilized and then deposited elsewhere in the core. We found that alpha-recoiled ²³⁴U is sensitive to differences in sediment …

Understanding The Impacts Of Topobathymetric Data On Storm Surge Model Predictions, Sydni Crain

Master's Theses

The topobathymetric characteristics of a region are regularly altered by natural and anthropogenic causes. This directly impacts the resulting storm surge during a hurricane. The primary goal of this research was to gain a better understanding of the impact that topography and bathymetry have on storm surge models, particularly the Advanced Circulation (ADCIRC) Model. Hurricane Zeta (2020) and Hurricane Ida (2021) were chosen as case studies; therefore, the Gulf of Mexico (GOM) was chosen as the study site. This research was completed by comparing ADCIRC storm surge results which were based on older, lower-resolution data with results derived from more …

Determining The Refractive Index Of Phytoplankton Via Direct Measurement Of Cellular Structures, Michael Kamowski

Master's Theses

The refractive index of phytoplankton has never been directly measured before despite its importance towards studying the optical characteristics of marine particles. Previous attempts to measure it have been done through indirect methods. While these methods have proven useful, they contain assumptions about the particles morphology and composition that cause for uncertainty with the measurements. Through the use of the 3D Cell Explorer, a high precision holotomographic microscope, the RI of phytoplankton can be directly measured for the first time. With volume measurements, the phytoplankton were found to not display a single bulk RI, instead the bulk RI was different …

Benthic Habitat Mapping Of Mountain Top Bank Within The Northern Gulf Of Mexico Through Integrated Geophysical And Visual Data Analysis, Bethany Pertain

Master's Theses

Mesophotic coral ecosystems (MCEs) are among the seafloor ecosystems that have been poorly studied throughout the world’s oceans, but they are a vital and diverse ecosystem that should be prioritized for future mapping and ecological studies. Priority should be given to them because they possess natural, social, and economic values, and face a variety of threats, all of which, if not better understood will result in the loss of this unique ecosystem. Insights into these ecosystems, among other deep-sea environments, are lacking due to difficulty accessing them, inherent lag between data collection by an autonomous system and observation by a …

Remote Internal Wave Forcing Of Regional Ocean Simulations Near The U.S. West Coast, Oladeji Q. Siyanbola, Maarten C. Buijsman, Audrey Delpech, Lionel Renault, Roy Barkan, Jay F. Shriver, Brian K. Arbic, James C. Mcwilliams

Faculty Publications

Low mode internal waves are able to propagate across ocean basins and modulate ocean dynamics thousands of kilometers away from their generation sites. In this study, the impact of remotely generated internal waves on the internal wave energetics near the U.S. West Coast is investigated with realistically forced regional ocean simulations. At the open boundaries, we impose high-frequency oceanic state variables obtained from a global ocean simulation with realistic atmospheric and astronomical tidal forcing. We use the Discrete Fourier Transform (DFT) technique in separating ingoing and outgoing internal tide energy fluxes at the open boundaries in order to quantify internal …

Epiphytic Diatom Production On The Seagrass Thalassia Testudinum In Northern Gulf Of Mexico, Jonathan L. Venable, Shayna A. Sura, Jeffrey W. Krause

Gulf and Caribbean Research

No abstract provided.