Physical Sciences and Mathematics Commons^™

A Numerical Investigation Of Tornado Production And Intensification In Tropical Cyclones, Marco Paredes

FIU Electronic Theses and Dissertations

The environmental conditions required for tornado formation and development in tropical cyclones (TCs) and the mechanisms underlying the intensification of TC tornadoes remain poorly understood. Previous research has suggested that low and mid-level dry air intrusion in TCs may enhance convective instability and influence the production of tornadoes. However, observations have their limitations in answering some of the key questions regarding the relationship among thermodynamic instability, dry air, and TC tornado genesis, development, and dissipation. In this study, a multiple nested Weather Research and Forecasting (WRF) model in a hindcasting mode is used to simulate Hurricane Ivan (2004) by resolving …

Climatology Of Rainfall Distribution And Asymmetries Of Tropical Cyclones: A Global Perspective, Oscar Guzman Rey

FIU Electronic Theses and Dissertations

Estimating the magnitude of tropical cyclone (TC) rainfall at different landfalling states is an important aspect of the TC forecast that directly affects the level of response from emergency managers in coastal areas. This research analyses the spatial distribution of the rainfall magnitude in tropical cyclones (TCs) at different stages over global oceans. The research’s central hypothesis is that TC rainfall exhibits distinct features in the long-term satellite dataset due to the evolution of the spatial distribution, radial variation, and asymmetries at the stages before, during, and after landfall. The resulting patterns are analyzed through a statistical approach that takes …

The Patterns Of Occurrence, Management, And Behavioral Ecology Of Fish Spawning Aggregations In Southeast Florida, Benjamin Binder

FIU Electronic Theses and Dissertations

The formation of fish spawning aggregations (FSAs) is an essential life history process for more than 150 species worldwide. Decades of research have provided a wealth of information to describe FSA dynamics, but there are many regions where their occurrence, behavior, and susceptibility to environmental variation remain uncharacterized. Even in regions that host an extensive research infrastructure such as South Florida, a standardized survey program to locate, validate, and monitor FSAs has not been established. This dissertation addresses those shortcomings in several ways. First, I present a comprehensive synthesis of available FSA literature from the region, which was combined with …

Selected Tropical Cyclone Satellite Analyses With An Emphasis On 37 Ghz Color Composite Imagery, Margaret Kieper

FIU Electronic Theses and Dissertations

This research expanded the understanding of the 37 GHz color composite imagery of tropical cyclones (using the Naval Research Lab Monterey image archive), by improved identification of precipitation types uniquely observed on this imagery, aided by creation of a conceptual model. This model distinguished between stratiform and convective rain, and identified the cyan color on this imagery as being warm rain from shallow and moderate convection, or "SAM." Patterns of SAM on this imagery uniquely identify tropical cyclone features: an early indicator of the onset of rapid intensification and early eyewall replacement cycles, both previously unobserved. These are identified by …

Drivers Of Extracellular Polysaccharide Production By A Mat-Forming Diatom, Kaitlin A. Stansbury

FIU Electronic Theses and Dissertations

Microbial biofilms are held together by extracellular polymeric substances (EPS), which can be secreted by many organisms. EPS production can facilitate intercellular communication and inter-guild microbial mutualisms, intraspecific gamete exchange, nutrient sequestration, and desiccation resistance. Benthic microbial mats (periphyton) of the Florida Everglades and other karstic wetlands contain abundant EPS generated by mat-producing filamentous blue-green algae and many other species of mat-dwelling algae, cyanobacteria, and bacteria, including the most abundant Everglades diatom, Mastagloia calcarea. The benthic diatom genus Mastogloia is characterized by several morphological and physiological features that foster production of a ‘halo’ of EPS around the frustule, but the …

Quantifying How Coastal Flooding And Stormwater Runoff Drive Spatiotemporal Variability In Carbon And Nutrient Processing In Urban Aquatic Ecosystems, Matthew A. Smith

FIU Electronic Theses and Dissertations

Coastal river networks alter the transport and transformation of dissolved organic carbon (DOC) and dissolved organic matter (DOM), which can vary in concentration and composition across spatiotemporal scales. Given climate-induced shifts in rainfall and tidal variation in low-lying coastal regions, there is an increasing need to quantify effects of flooding on biogeochemical cycling. Specifically, urban flooding is becoming increasingly common due to biophysical alterations to hydrology from urbanization and climate change. Urban ecosystems have been characterized as having a distinct biogeochemistry compared to other systems, largely due to increased frequency and magnitude of riverine and coastal flooding. Consequently, the role …

Comparison Of Modern And Mid-Holocene Benthic Foraminifera To Assess Recent Environmental Change In Almirante Bay, Caribbean Panama, Maria N. Gudnitz

FIU Electronic Theses and Dissertations

This study used the diversity and distribution of benthic foraminiferal assemblages of Almirante Bay, Caribbean Panama, as environmental proxies to compare modern coral, seagrass and mangrove habitats to mid-Holocene coral reef facies on the island of Isla Colón, to investigate both natural and human-influenced changes.

The modern study associated species and assemblage characteristics with environmental conditions related to degraded water quality. Assemblages were fairly similar among neighboring habitats but differed in species proportions, while several stress-tolerant taxa might indicate eutrophic conditions. Diversity appeared to be regionally controlled by freshwater input irrespective of habitat type, was generally lower near the mainland …

Microphysical-Dynamical Interaction In Tropical Cyclone Intensification, Zongyao Yang

FIU Electronic Theses and Dissertations

Producing timely and accurate tropical cyclone (TC) intensity forecasts remains one of the most difficult challenges facing meteorologists today. The state-of-the-art three-dimensional (3D) full physics operational models, in particular, have problems in simulating rapid intensification (RI), a situation where a TC intensifies dramatically in a short period of time. For example, Hurricanes Patricia (2015) and Maria (2017) increased their maximum sustained winds by 90 knots and 70 knots within 24 hours, respectively. The major objectives of this dissertation are to (a) explore the underlying reasons why the Hurricane Weather Research and Forecasting (HWRF) system, one of the operational models used …

Connections In The Underworld: A Morphological And Molecular Study Of Diversity And Connectivity Among Anchialine Shrimp., Robert Eugene Ditter

FIU Electronic Theses and Dissertations

This research investigates the distribution and population structure of crustaceans, endemic to anchialine systems in the tropical western Atlantic focusing on cave-dwelling shrimp from the family Barbouriidae. Taxonomic and molecular tools (genetic and genomic) are utilized to examine population dynamics and the presence of phenotypic hypervariation (PhyV) of the critically endangered species Barbouria cubensis (von Martens, 1872). The presence of PhyV and its geographic distribution is investigated among anchialine populations of B. cubensis from 34 sites on Abaco, Eleuthera, and San Salvador, Bahamas. Examination of 54 informative morphological characters revealed PhyV present in nearly 90% (n=463) of specimens with no …

Lithological And Geochemical Responses To Abrupt Global And Regional Paleoenvironmental Changes During The Aptian In A Hemipelagic Setting Of The Eastern Iberian Peninsula: A Multi-Proxy Approach, Jander Socorro

FIU Electronic Theses and Dissertations

Intense episodes of environmental perturbations and regionally to globally distributed, oxygen-deprived marine facies characterize the Cretaceous sedimentary record. The Organyà Basin in the Spanish Pyrenees chronicles this period in expanded stratigraphic sequences that enabled high-resolution sampling and detailed analysis of disturbances poorly recorded in more lithologically condensed sections. Here, I present an integrated multi-proxy study aimed at understanding the Basin’s response to changing paleoenvironmental conditions during the early Aptian stage of the Cretaceous.

Results from the El Pui section indicate that large-scale (> 1‰), negative carbon isotope excursions (CIEs) that show no corresponding shifts in local sources of organic matter …

Wavenumber-1 Vortex Rossby Wave Propagation In The Inner Waveguide Of A Modeled, Barotropic Nondivergent Tropical Cyclone, Israel Gonzalez

FIU Electronic Theses and Dissertations

Vortex Rossby waves (VRWs) have been shown to influence tropical cyclone (TC) structure and intensity change. However, the role of VRWs in TC motion and analyses of the inner waveguide within which the waves propagate have received limited attention. Therefore this dissertation primarily focuses on modeling wavenumber-1 VRWs in a barotropic, nondivergent context to investigate TC-like vortex motion, acquire deeper understanding of propagation within the widest possible inner waveguide, and compare with higher-wavenumber studies.

A mass source-sink pair rotating with a specified frequency is imposed in a mean vortex’s eyewall to excite VRWs. Forced waves manifest as vorticity filaments that …

Stable Isotope Analysis Of Japan Sea And East China Sea Sediments: Late Pleistocene Paleoceanographic Reconstructions, Heather Dawn Black

FIU Electronic Theses and Dissertations

The East Asian Monsoon system is an important dynamic of East Asian climates, affecting over one-third of the world’s population. Marginal seas within East Asia are ideal environments to study past fluctuations of monsoon intensities and durations as they are sensitive to climatic and glacio-eustatic sea level changes. This study focuses on continuous sedimentary sequences collected from three Integrated Oceanic Drilling Program Expedition 346 sites; Sites U1426 and U1427 in the Japan Sea and Site U1429 in the East China Sea. Elemental concentration (%TOC, %TN, and %CaCO₃) and stable isotope ratios (δ¹³C and δ¹⁵N) …

Evaluating Changes To Natural Variability On A Warming Globe In Cmip5 Models, Heather Vazquez

FIU Electronic Theses and Dissertations

Global mean surface temperatures (GMST) warmed in the early 20th century, experienced a mid-century lull, and warmed again steadily until 1997. Observations at the turn of the 21st century have revealed another period of quiescent warming of GMSTs from 1998 to 2012, thus prompting the notion of a global warming “hiatus”. The warming hiatus occurred concurrently with steadily increasing atmospheric greenhouse gas concentrations, sea level rise, and retreating arctic sea ice. The occurrence of the warming hiatus suggests that natural variability continues to be a sizable contributor to modern climate change and implies that energy is rearranged or changed within …

Developing Ocean Color Algorithm Using Moderate Resolution Imaging Spectroradiometer (Modis) Sensor For Shallow Coastal Water Bodies, Mohd Manzar Abbas

FIU Electronic Theses and Dissertations

This study analyses the spatial and temporal variability of chlorophyll-a in Chesapeake Bay; assesses the performance of Ocean Color 3M (OC3M) algorithm; and develops a novel algorithm to estimate chlorophyll-a for coastal shallow water. The OC3M algorithm yields an accurate estimate of chlorophyll-a concentration for deep ocean water (RMSE=0.016), but it failed to perform well in the coastal water system (RMSE=23.17) of Chesapeake Bay. A novel algorithm was developed which utilizes green and red bands of the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. The novel algorithm derived the chlorophyll-a concentration more accurately in Chesapeake Bay (RMSE=4.20) than the OC3M algorithm. …

Changes In Soil Microbial Functioning In Coastal Wetlands Exposed To Environmental Stressors And Subsidies, Shelby M. Servais

FIU Electronic Theses and Dissertations

Environmental perturbations are ubiquitous features of ecosystems and shape ecological structure and function. Climate change will alter the intensity and frequency of disturbances and expose ecosystems to novel combinations of useful inputs (subsidies) and harmful inputs (stressors). Coastal wetlands are particularly vulnerable to changing environmental conditions and are increasingly exposed to effects of interacting subsidies and stressors. In particular, the Florida Coastal Everglades, which has experienced accelerated change due to a history of water management practices, is vulnerable to new disturbances associated with climate change. The low-lying Florida Everglades faces multiple disturbances from storm surge, nutrient enrichment, and sea-level rise …

Trend And Acceleration: A Multi-Model Approach To Key West Sea Level Rise, John Tenenholtz

FIU Electronic Theses and Dissertations

Sea level rise (SLR) varies depending on location. It is therefore important to local residents, businesses and government to analyze SLR locally. Further, because of increasing ice melt and other effects of climate change, rates of SLR may change. It is therefore also important to evaluate rates of change of SLR, which we call sea level acceleration (SLA) or deceleration.

The present thesis will review the annual average sea level data compiled at the Key West tidal gauge in Key West, Florida. We use a multi-model approach that compares the results of various models on that data set. The goal …

Quantification Of Precipitation Asymmetries In Tropical Cyclones And Their Relationship To Storm Intensity Changes Using Trmm Data, Yongxian Pei

FIU Electronic Theses and Dissertations

The climatology of precipitation asymmetries in Tropical Cyclones (TCs) and their relationship to TC intensity changes using 16 years of data from the Tropical Rainfall Measuring Mission (TRMM) satellite. TC Inner core precipitation asymmetries were quantified using the Fourier wavenumber decomposition method upon the pixel level data of 3,542 TRMM TMI overpasses. Composites of wavenumber–1 and wavenumber 1–6 total precipitation asymmetries were constructed to show the distribution pattern under different storm motion speed, vertical wind shear and the combined effects of varying vertical wind shear and storm motion. Results indicate that motion–relative total precipitation asymmetry is located down–motion. The phase …

Rip Current Formation And Beach Safety Implications For Several U.S. Atlantic Coast Beach Areas, Kathleen Michelle Fallon

FIU Electronic Theses and Dissertations

This dissertation combines seemingly different studies, which work together to describe the physical characteristics of rip current development and associated social implications at several locations. These fast-moving, concentrated flows of water travel offshore and can be found on any beach with sufficient wave action. Any event of increased wave steepness will erode a large quantity of sediment from the beach. The material deposited offshore eventually makes its way back; during this process, ocean water becomes trapped behind a shore-attached bar resulting in a ridge-and-runnel. These formations are seen at East Hampton, where rip-like currents form as concentrated water drains from …

Evaluation And Predictability Of Observation-Based Surface Wind Asymmetric Structure In Tropical Cyclones, Bradley Klotz

FIU Electronic Theses and Dissertations

Surface wind speeds are an important and revealing component of the structure of tropical cyclones (TCs). To understand the asymmetric structure of surface winds in TCs associated with differences in formation region, environmental wind shear, storm forward motion, and TC strength and intensification, a twelve year database of satellite scatterometer data are utilized to produce composite total wind speed and Fourier-derived, low wavenumber analyses. A quantified asymmetry is determined as a function of TC intensity and reveals the tropical storms are influenced by wind shear at all TC-centric radii but only for areas away from the radius of maximum wind …

Vortex Rossby Wave Propagation In Three Dimensional Tropical-Cyclone-Like Baroclinic Vortices, Cen Gao

FIU Electronic Theses and Dissertations

This study aims to advance our understanding of the inner-core dynamics of tropical cyclones (TCs) from the perspective of vortex Rossby waves (VRWs) through investigating wave kinematics, propagation feature, and wave-mean-flow interaction in three dimensional TC-like baroclinic vortices. Using the Wenzel-Kramers-Brillouin analysis in the asymmetric balanced model framework, the generalized wave dispersion relation, group velocities, and stagnation radius/height of VRW wave-packets in both pseudo-height and isentropic coordinates are derived. It is found that the VRW dispersion relation associated with baroclinic vortices in an isentropic coordinate has the same format as that of barotropic vortices in a pseudo-height coordinate. However, baroclinicity …

Evaluation Of Surface Layer Parameterizations Using In-Situ Observations, Jeremy Katz

FIU Electronic Theses and Dissertations

Appropriate calculation of surface turbulent fluxes between the atmosphere and the underlying surface is one of the major challenges in geosciences. In practice, the surface turbulent fluxes are estimated from the mean surface meteorological variables based on the bulk transfer model combined with Monnin-Obukhov Similarity (MOS) theory. Few studies have been done to examine the extent that to which this flux parameterization framework can be applied to different weather and surface conditions. A novel validation method is developed in this thesis research, which is applied to evaluate the surface flux parameterization using in-situ observations. The main findings are: (a) the …

Models Describing The Sea Level Rise In Key West, Florida, Karm-Ervin Jean

FIU Electronic Theses and Dissertations

Lately, we have been noticing an unusual rise in the sea level near many Floridian cities. By 2060, scientists believe that the sea level in the city of Key West will reach between 22.86 to 60.96 centimeters (Strauss et al. 2012). The consequences of sea level rise are unpleasant by gradually tearing away our beaches and natural resources, destroying our homes and businesses, etc. Definitively, a continual increase of the sea level will affect everyone either directly or indirectly.

In this study, the sea level measurements of four Floridian coastal cities (including Key West) are collected in order to describe …

Robust Modeling And Predictions Of Greenhouse Gas Fluxes From Forest And Wetland Ecosystems, Khandker S. Ishtiaq

FIU Electronic Theses and Dissertations

The land-atmospheric exchanges of carbon dioxide (CO₂) and methane (CH₄) are major drivers of global warming and climatic changes. The greenhouse gas (GHG) fluxes indicate the dynamics and potential storage of carbon in terrestrial and wetland ecosystems. Appropriate modeling and prediction tools can provide a quantitative understanding and valuable insights into the ecosystem carbon dynamics, while aiding the development of engineering and management strategies to limit emissions of GHGs and enhance carbon sequestration. This dissertation focuses on the development of data-analytics tools and engineering models by employing a range of empirical and semi-mechanistic approaches to robustly …

Spatio-Temporal Analysis Of Chilling Events In Mangrove Forests Of South Florida, Bina Thapa

FIU Electronic Theses and Dissertations

Chilling events are infrequent but important disturbances in subtropical Florida. When temperatures drop to near freezing, significant mortality often accrues in mangrove forests. Chilling events play a role in maintaining structural diversity in mangrove forests, and in limiting mangrove poleward distribution. I examined the spatio-temporal distribution of chilling events in mangrove forests of southern Biscayne Bay by using Landsat TM5 images since 1989. Damage was usually confined to dwarf mangrove forest, especially when chilling temperatures were moderate and short in duration. However, damage from extended and severe freezes such as in January 2010 impacted larger trees as well. Recovery is …

Distribution Fits For Various Parameters In The Hurricane Model, Victoria Oxenyuk

FIU Electronic Theses and Dissertations

The FPHLM is the only open public hurricane loss evaluation model available for assessment of hazard to insured residential property from hurricanes in Florida. The model consists of three independent components: the atmospheric science component, the vulnerability component and the actuarial component. The atmospheric component simulates thousands of storms, their wind speeds and their decay once on land on the basis of historical hurricane statistics defining wind risk for all residential zip codes in Florida.

The focus of the thesis was to analyze atmospheric science component of the Florida Public Hurricane Loss Model, replicate statistical procedures used to model various …

Mechanisms Governing The Eyewall Replacement Cycle In Numerical Simulations Of Tropical Cyclones, Zhenduo Zhu

FIU Electronic Theses and Dissertations

Eyewall replacement cycle (ERC) is frequently observed during the evolution of intensifying Tropical Cyclones (TCs). Although intensely studied in recent years, the underlying mechanisms of ERC are still poorly understood, and the forecast of ERC remains a great challenge. To advance our understanding of ERC and provide insights in improvement of numerical forecast of ERC, a series of numerical simulations is performed to investigate ERCs in TC-like vortices on a f-plane. The simulated ERCs possess key features similar to those observed in real TCs including the formation of a secondary tangential wind maximum associated with the outer eyewall. The Sawyer-Eliassen …

Comparison And Validation Of Tropical Rainfall Measuring Mission (Trmm) Rainfall Algorithms In Tropical Cyclones, Joseph P. Zagrodnik

FIU Electronic Theses and Dissertations

Tropical Rainfall Measuring Mission (TRMM) rainfall retrieval algorithms are evaluated in tropical cyclones (TCs). Differences between the Precipitation Radar (PR) and TRMM Microwave Imager (TMI) retrievals are found to be related to the storm region (inner core vs. rainbands) and the convective nature of the precipitation as measured by radar reflectivity and ice scattering signature. In landfalling TCs, the algorithms perform differently depending on whether the rainfall is located over ocean, land, or coastal surfaces. Various statistical techniques are applied to quantify these differences and identify the discrepancies in rainfall detection and intensity. Ground validation is accomplished by comparing the …