Meteorology 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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …