Observational study of small-scale features present in the hurricane boundary layer
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The understanding of the overall hurricane wind structure has constantly progressed over the years. However, predicting and modeling irregularities in the surface wind field that are believed to be responsible for some of the observed discrepancies between the mean surface wind of tropical cyclones and resulting damage patterns remain a scientific challenge. Hurricane boundary layer (HBL) smaller-scale features are thought to be one of the causes of these surface wind irregularities but, because of a significant lack of high resolution observations of these phenomena, little is known about their structure and relationship with the underlying surface wind field. In order to answer these questions, the Texas Tech University Hurricane Intercept Team designed and conducted two field experiments focusing exclusively on documenting the smaller scales of motion in the HBL wind. High-resolution Shared Mobile Atmospheric Research and Teaching (SMART) radars and instrumented 10-m towers were deployed during the landfalls of Hurricanes Isabel (2003) and Frances (2004) resulting in the collection of an unprecedented data set. The data were processed to investigate HBL small-scale features. The radar data were used to study the physical characteristics and three-dimensional structure of the small-scale features. A unique in-depth wavelength analysis was conducted and various scales of motion of the HBL were examined. A spectral analysis of accompanying tower data was produced to establish the correlation between the signature of the small-scale features and the underlying near-surface wind field. Comparisons to previous research studies were made to highlight similarities and differences.