Browsing by Subject "Hurricane Bonnie, 1998"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Hurricane Bonnie wind flow characteristics(Texas Tech University, 1999-12) Schroeder, John L.Whether convective influences result in localized areas of increased wind speeds and different turbulent structure than expected in a normal high wind situation has been debated for years. The question has been especially active concerning landfalling hurricanes. Given a lack of high-resolution wind speed data from within hurricanes necessary to resolve the debated questions, a field experiment was designed and conducted by Texas Tech University to acquire the necessary data. The Wind Engineering Mobile Instrumented Tower Experiment (WEMITE), the first successful field experiment to place a reinforced, self-powered, instrumented tower directly in the path of several hurricanes, successfully gathered high-resolution wind speed data from within Hurricane Bonnie as it made landfall near Cape Fear, North Carolina, on 26 August 1998, at 5:00 PM. These data are used to inspect the variations in turbulent characteristics of the wind during the passage of the storm. Specifically, turbulence intensities, integral scales, gust factors, and spectrograms are evaluated with respect to the surrounding meteorological events, such as the passage of rainbands. Comparisons are drawn between turbulence intensity and integral scale values present in Hurricane Bonnie, and those employed in the determination of the gust effect factor in ASCE 7-98. Wavelet analysis was also used to examine the incoherent model assumption employed in wind engineering.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.