Hurricane Boundary Layer Small-Scall Features Observed using RHI Data Coupled with VAD Analysis

Understanding the boundary layer of hurricanes at landfall has been one of the main interests of the Texas Tech University Hurricane Intercept team. For several years, the TTU team has deployed instrumented towers along the path of landfalling hurricanes in order to document their surface windfield structure. In addition, the mobile SMART-Radars were later used to complement the tower data and to allow for a more comprehensive depiction of the hurricane boundary layer (HBL) flow at landfall. The SMART-Radars, with a gate spacing up to 66.7 m, were an appropriate instrument to acquire high spatial resolution data of hurricane boundary layers.

SMART-Radar data have been collected during several recent hurricane seasons. One of the goals of the deployments was to acquire high-resolution data that would permit identification and analysis of small-scale features embedded in the HBL which are thought to be responsible for perturbations in the surface windfield. The radars were predominantly used in PPI mode. However, during the landfalls of Hurricane Isabel (2003) and Hurricane Frances (2004), RHI scanning strategies were added, so that the vertical extent of the boundary layer could be investigated. VAD processing was first performed on the PPI data. Then the results were incorporated into the RHI analysis. Small-scale linear features already identified in the PPI data were also identified in the RHI data after processing.