Browsing by Author "Skwira, Gary D."
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Item Monte Carlo simulation for the United States Gulf and Atlantic coast(Texas Tech University, 1998-12) Skwira, Gary D.Hurricanes have caused bllions of dollars of damage and claimed many lives over the years. Hurricanes not only devastate the people and buildings directly in the path of their fury, but they affect all of society. After a hurricane makes landfall (especially in a populated area) all of society bears the burden of the economic recovery. Such an event can be quite taxing. For this reason it is especially critical that hurricanes be studied in order to more fully understand them. With an increased understanding of hurricanes the public can be better prepared for and mitigate such disasters. Hurricanes are major events, but since they happen relatively infrequently at any one location, meaningful statistics cannot be compiled at a single site from the historical records. Thus, an indirect method of obtaining useful hurricane wind statistics is needed. One such method investigated in this thesis is known as a Monte Carlo simulation. A Monte Carlo simulation is a procedure whereby many idealized tropical storms and hurricanes are generated using a computer simulation. In this procedure, relevant meteorological parameters such as the radius of maximum winds, the central pressure, and the speed and direction of the hurricanes motion are randomly selected from probability density functions developed from historic data. The information selected is then used to initialize the wind field model. The hurricane is then propagated, and the maximum wind speed and wind direction at the site of interest is captured. This process of initialization of the hurricane wind field, propagation of the hurricane, and capturing of the maximum wind speed and direction at the site is performed repeatedly. Assuming the hurricane wind model and the hurricane parameter statistics are reasonable for the site in question, statistically significant wind statistics result. The resulting database of wind speeds and directions can be used by engineers to establish load factors for the design of structures. This thesis takes a closer look at the Monte Carlo simulation method for a number of sites along the United States Gulf and Atlantic Coast. The resulting wind statistics are then presented and a number of interpretations, conclusions, and possible suggestions are discussed.Item Surface observations of landfalling hurricane rainbands: case studies of Hurricane Bonnie (1998) and Hurricane Dennis (1999)(Texas Tech University, 2003-05) Skwira, Gary D.This study examines the rainband-scale fluctuations of the meteorological parameters for Hurricane Bonnie (1998) and Dennis (1999). Since reliable surface observations near the locations of landfalling hurricanes are quite rare due to power and/or instrumentation failure. Wind Engineering Mobile Instrumented Tower Experiment (WEMITE) data are exploited to provide a unique look into the structure of the captured storms. The WEMITE data consists of high-resolution meteorological data—including wind speed and direction, temperature, relative humidity, and pressure— gathered from within the planetary boundary layer of landfalling hurricanes along the United States coastline. WEMITE data, along with supplemental data gathered by the National Weather Service, buoys, Coastal Marine Automated Network (CMAN) stations, dropsondes and hurricane hunter observations, are assembled and analyzed through the use of Geographic Information Systems (GIS). Furthermore, nearby Next Generation Weather Surveillance Radar (NEXRAD WSR-88D) data are used to identify and examine rainbands found within the hurricanes of interest. The observed meteorological profiles are compiled and the results are compared to previous rainband studies. The observed meteorological data suggest equivalent potential temperature minima, decreasing hurricane-relative inflow, and large-scale convergence to be commonly associated with intensifying or mature landfalling hurricane rainbands. Additionally, the results suggest larger rainbands (l00's of km long) promote updrafts and reflectivity redevelopment to the inside of their axis. The shorter bands (100 km or less in length), conversely, tend to form from one or a number of cells that are elongated into a band by strong hurricane winds with regeneration upband.