Oceanography and Atmospheric Sciences and Meteorology Commons^™

Nonlinear Behaviour Of Sea Surface Waves Based On Low-Gradient Phase-Only Scattering Effects, Jonathan Blackledge, Eugene Coyle, Derek Kearney

Conference papers

Nonlinear sea waves generated by the wind, including freak waves, are considered to be phenomena that can be modelled using the nonlinear (cubic) Schrodinger equation, for example. However, there is a problem with this approach which is that sea surface waves, driven by wind speeds of varying strength, must be considered to be composed of two distinct types, namely, linear waves and nonlinear waves. In this paper, we consider a different approach to modelling ‘nonlinear’ waves that is based on a solution to the linear wave equation under a low-gradient, phase-only condition. This approach is entirely compatible with the fluid …

Upscaling Carbon Fluxes Over The Great Plains Grasslands: Sinks And Sources, Li Zhang, Bruce K. Wylie, Lei Ji, Tagir G. Gilmanov, Larry L. Tieszen, Daniel M. Howard

Natural Resource Management Faculty Publications

Previous studies suggested that the grasslands may be carbon sinks or near equilibrium, and they often shift between carbon sources in drought years and carbon sinks in other years. It is important to understand the responses of net ecosystem production (NEP) to various climatic conditions across the U.S. Great Plains grasslands. Based on 15 grassland flux towers, we developed a piecewise regression model and mapped the grassland NEP at 250 m spatial resolution over the Great Plains from 2000 to 2008. The results showed that the Great Plains was a net sink with an averaged annual NEP of 24 ± …

Improving Simulations Of The Upper Ocean By Inclusion Of Surface Waves In The Mellor-Yamada Turbulence Scheme, Chuan Jiang Huang, Fangli Qiao, Zhenya Song, Tal Ezer

CCPO Publications

The Mellor-Yamada turbulence closure scheme, used in many ocean circulation models, is often blamed for overly high simulated surface temperature and overly low simulated subsurface temperature in summer due to insufficient vertical mixing. Surface waves can enhance turbulence kinetic energy and mixing of the upper ocean via wave breaking and nonbreaking-wave-turbulence interaction. The influences of wave breaking and wave-turbulence interaction on the Mellor-Yamada scheme and upper ocean thermal structure are examined and compared with each other using one-dimensional and three-dimensional ocean circulation models. Model results show that the wave-turbulence interaction can effectively amend the problem of insufficient mixing in the …

A Terrestrial Gamma Ray Flash Observed From An Aircraft, D. M. Smith, Michael E. Splitt, Steven M. Lazarus

Aerospace, Physics, and Space Science Faculty Publications

On 21 August 2009, the Airborne Detector for Energetic Lightning Emissions (ADELE), an array of six gamma-ray detectors, detected a brief burst of gamma rays while flying aboard a Gulfstream V jet near two active thunderstorm cells. The duration and spectral characteristics of the event are consistent with the terrestrial gamma ray flashes (TGFs) seen by instruments in low Earth orbit. A long-duration, complex +IC flash was taking place in the nearer cell at the same time, at a distance of ∼10 km from the plane. The sferics that are probably associated with this flash extended over 54 ms and …

Assessment Of Black Carbon In Snow And Ice From The Tibetan Plateau And Pacific Northwest, Matthew Glen Jenkins

All Master's Theses

An ice core from Mt. Geladandong, Tibetan Plateau, spanning 1853-1983, and snow samples collected over two winters from the Cascade Mountains were analyzed for concentrations of black carbon (BC) using a Single Particle Soot Photometer (SP2). From the ice core, the high-resolution BC record displayed substantial variability, a 2-fold increase in peak concentrations from 1853-1930 to 1930-1983, and a 1.6-fold increase in average concentrations from 1853-1975 to 1975-1983. Concentrations were also higher than at two areas closer to BC sources and analyzed by the same method. In the Pacific Northwest, BC concentrations varied seasonally and annually, with the highest concentrations …

State Of The River Report For The Lower St. Johns River Basin, Florida: Water Quality, Fisheries, Aquatic Life, And Contaminants 2011, Environmental Protection Board, City Of Jacksonville, University Of North Florida, Jacksonville University

State of the River Report

No abstract provided.

Modeling The Population Effects Of Hypoxia On Atlantic Croaker (Micropogonias Undulatus) In The Northwestern Gulf Of Mexico, Sean Brandon Creekmore

LSU Master's Theses

The northwestern Gulf of Mexico currently experiences a large hypoxic area (“dead zone”) during the summer. While the local effects of hypoxia on organisms have been documented, the population-level effects are largely unknown. I developed a spatially-explicit, individual-based model to analyze how hypoxia effects on Atlantic croaker reproduction, growth, and mortality in the northwestern Gulf of Mexico could lead to population-level responses. The model follows the hourly growth, mortality, reproduction, and movement of individuals on a 300 x 800 spatial grid of 1 km2 cells for 100 years. Chlorophyll-a concentration, water temperature, and dissolved oxygen were specified daily for each …

Oceanic Light Absorption Properties: Assessment And Characterization In The Southeastern Bering Sea Using Field And Satellite Observations, Puneeta Suresh Naik

LSU Doctoral Dissertations

In recent decades the Bering Sea has been subjected to large climatic variability with cascading consequences on its productive marine ecosystem. Long-term as well as short-term monitoring is essential if we are to maintain its capability to supply the resources on which the national and local economy depend. Remote sensing together with in-situ and laboratory measurements of physical, biological and optical properties have considerable potential for monitoring and measuring the effects of climate-driven changes on this ecosystem. A major shortcoming to obtain accurate estimates of optically active components (such as colored dissolved organic matter, non-algal particulate matter, and phytoplankton) from …

Hurricane Induced Land And Vegetation Changes In The Breton Sound Estuary And Chandeleur Islands Using Landsat 5 Tm, Vandana Varshini Raghunathan

LSU Master's Theses

This study focuses on hurricane-induced changes in land and vegetation primarily in two study areas, the Breton Sound Estuary and the Chandeleur Islands, southeast of New Orleans, Louisiana. Breton Sound Estuary consists of the Caernarvon Diversion, a fresh water diversion of the Mississippi River that supplies this region with managed pulses of fresh water and sediments. The Chandeleur Islands are a chain of barrier islands that are uninhabited and transgressive in nature. A sequence of hurricanes in the past two decades has greatly altered both areas significantly. Satellite data were analyzed for a period of 24 years (1987-2011) of Breton …

Early Season Depletion Of Dissolved Iron In The Ross Sea Polynya: Implications For Iron Dynamics On The Antarctic Continental Shelf, Peter N. Sedwick, C. M. Marsay, B. M. Sohst, A. M. Aguilar-Islas, M. C. Lohan, M. C. Long, K. R. Arrigo, R. B. Dunbar, M. A. Saito, W. O. Smith, G. R. Ditullio

OES Faculty Publications

The Ross Sea polynya is among the most productive regions in the Southern Ocean and may constitute a significant oceanic CO₂sink. Based on results from several field studies, this region has been considered seasonally iron limited, whereby a "winter reserve" of dissolved iron (dFe) is progressively depleted during the growing season to low concentrations (~ 0.1 nM) that limit phytoplankton growth in the austral summer (December-February). Here we report new iron data for the Ross Sea polynya during austral summer 2005-2006 (27 December-22 January) and the following austral spring 2006 (16 November-3 December). The summer 2005-2006 data show …

Comparison Of The Age And Growth Of Red Snapper (Lutjanus Campechanus) Amongst Habitats And Regions In The Gulf Of Mexico, Courtney Rose Saari

LSU Master's Theses

The Gulf of Mexico (GOM) red snapper stock has been exploited since the mid 1800s; yet it is still one of the most economically important fisheries in the GOM. Red snapper have been managed as a unit stock and are currently overfished, but perhaps no longer undergoing overfishing. Habitat varies greatly throughout the GOM and while numerous studies have aged red snapper, none have simultaneously compared the age and size structure and growth rates among standing and toppled oil and gas platforms with natural habitats. The objectives of this study were to examine the size and age structure and growth …

From Source To Sink: An Isotopic Perspective On The Biogeochemical Relationship Between The Everglades And Florida Bay, Ana Maria Hoare

USF Tampa Graduate Theses and Dissertations

Increasing human populations and activities in coastal areas have led to high nutrient loading and estuarine ecosystem decline. Natural hydrological patterns in South Florida have been drastically altered by changes in water management and land use practices. As a result Florida Bay has experienced a series of negative ecosystem effects including hypersalinity events, degradation of water quality, and harmful algal blooms and declines in upper trophic level populations. To remediate ecosystem decline in Florida's coastal ecosystems, the Comprehensive Everglades Restoration Plan proposes to restore a more natural hydrologic flow in the Everglades. It is expected hydrologic restoration efforts will change …

Improvements To A Real-Time, Satellite-Derived Surface Current Product (Oscar) And Evaluation In The Intra-American Sea, Mindy Jo Robinson

USF Tampa Graduate Theses and Dissertations

A method of creating real-time height fields using available gridded altimetry data combined with extrapolated values computed using linear predictive coding for use in the Ocean Surface Currents Analysis, Real-time (OSCAR) is developed and tested. This method is implemented by Earth and Space Research (ESR) to produce operational height fields that are in turn used to calculate the geostrophic component velocity of OSCAR. The gridded altimetry product used in OSCAR is evaluated against sea level measured by tide gauges while the operational total near-surface velocity from OSCAR (geostrophic plus Ekman component velocity) is evaluated using ocean velocities from moored and …

Foraminiferal Assemblages On Sediment And Reef Rubble At Conch Reef, Florida Usa, Christy Michelle Stephenson

USF Tampa Graduate Theses and Dissertations

Benthic foraminiferal assemblages are widely used to interpret responses of the benthic communities to environmental stresses. This study compares epibiotic foraminiferal assemblages, collected from reef rubble, with those from reef sediments. The study site, Conch Reef, is the site of the Aquarius Underwater Habitat research facility and includes protected areas used only for scientific studies. Although a number of studies have enumerated foraminiferal taxa from the Florida reef tract, no projects have focused on the assemblages that occur at Conch Reef.

Sediment and reef rubbles samples were collected via SCUBA from a depth range of 13 to 26 m during …

Assessment Of Fertility Potential In Bottlenose Dolphins (Tursiops Truncatus): An Elisa-Based Biomarker Analysis, Leslie Schwierzke Wade

USF Tampa Graduate Theses and Dissertations

As apex predators in coastal systems, bottlenose dolphins (Tursiops truncatus) are susceptible to persistent organic pollutant (POP) accumulation and retention over time, which has prompted continued interest in understanding the extent to which contaminant body burdens or other stressors are sufficient to cause adverse sublethal effects on energetic fitness, immune function, or reproduction. Increasing our knowledge of reproductive endocrinology in bottlenose dolphins may provide insight into changes in reproductive rates, thereby expanding the capacity to assess conservation status. This study used the Enzyme-Linked ImmunoSorbent Assay (ELISA) technique to examine peptide fertility hormones [inhibin A, inhibin B and anti-Müllerian …

Dynamics Of Stony Coral Assemblages On Patch Reefs Of The Upper Florida Reef Tract, Including Biscayne National Park, Amy Wallace

USF Tampa Graduate Theses and Dissertations

The patch reefs located in Biscayne National Park (BNP) are some of the most northern reefs of the Florida reef system. The focus of my study is seven patch reefs that were first surveyed annually between 1977 and 1981, revealing 8% - 28% cover by scleractinian corals. An assessment of BNP patch reefs completed in 2000 reported that coral cover had decreased to approximately 0.4% - 10%. The once dominant species in the Florida reef tract, Acropora palmata and A. cervicornis, have rapidly declined over time and were not found in any transects during the 2000 survey.

This study is …

Sex And The Seas: Gene Transfer Agents, Elizabeth Young

USF Tampa Graduate Theses and Dissertations

Gene Transfer Agents (GTAs) are phage-like pthesiss that are produced by many alpha proteobacteria in late stationary growth phase and are capable of transferring chromosomal genes (termed "constitutive transduction"). Examination of alpha proteobacterial genomic sequences indicated widespread occurrence of GTA-like elements. The goal of this study was to investigate gene transfer potential of GTAs of marine alpha proteobacteria in culture as well as in natural marine environments. Another goal was to determine the potential of bacterial symbionts from zooxanthellae and coral to genetically transfer beneficial properties between symbionts. Ruegeria mobilis (ID 45A6) was isolated from cultures of the coral endosymbiotic …

Fate Of Mississippi River Diverted Nitrate On Vegetated And Non-Vegetated Coastal Marshes Of Breton Sound Estuary, Christine M. Vanzomeren

LSU Master's Theses

The Caernarvon Diversion meters Mississippi River water into coastal marshes of Breton Sound. Elevated levels of nitrogen in river water have sparked concerns that nutrient loading may affect marsh resilience and belowground biomass, as evidence from several marsh fertilization studies. These concerns resulted from observation that fresh and brackish Breton Sound marshes suffered extensive damage from Hurricane Katrina. The goal of this study is to determine the fate of nitrate (the dominant inorganic nitrogen form in the Mississippi River) in Breton Sound Estuary marshes. We hypothesized that most nitrate would be removed by denitrification and that nitrate loading would not …

Underwater Hearing In The Loggerhead Turtle (Caretta Caretta): A Comparison Of Behavioral And Auditory Evoked Potential Audiograms, Kelly Martin

USF Tampa Graduate Theses and Dissertations

Methods for collecting behavioral audiograms are often time consuming and require trained, captive subjects. It is more practical to measure hearing sensitivity using electrophysiological methods, such as auditory evoked potential (AEP) testing, in which electrodes measure action potentials in response to acoustic stimuli. These data can be collected in a matter of hours. However, results should be verified through behavioral testing. Current knowledge of marine turtle auditory abilities is based on a few electrophysiological tests. The purpose of this study was to collect and compare behavioral and auditory evoked potential audiograms in a captive adult loggerhead turtle (Caretta caretta …

Stable Isotope Studies Of Paleoenvironment And Paleoclimate From Afar, Ethiopia, Zelalem K. Bedaso

USF Tampa Graduate Theses and Dissertations

The sedimentary deposits of the Hadar Formation at Dikika and the Mount Galili Formation at Galili preserve a wealth of paleoenvironmental and paleoclimatic records spanning the last 5.29 Ma. Stable carbon and oxygen isotopic compositions of herbivore tooth enamel were analyzed for more than 600 specimens of 15 different taxa from 10 stratigraphic intervals. The application of carbon and oxygen isotopes here aims principally at reconstructing shifts in the relative abundance of C₄ grasses, and its implications for climate indicators including temperature, aridity, and seasonality. The full range of δ¹³C_enamel values throughout the Plio-Pleistocene signifies a …