Surface drag coefficient behavior during Hurricane Ike

As a result of increasing wealth, infrastructure, and population along the hurricane prone coast, there is a growing need for observations of surface layer quantities to improve hurricane and wave/surge forecasting. Results are presented from a field campaign coordinated among Texas Tech University (TTU), the University of Florida (UF), and the University of Notre Dame (UND) during the 2008 Atlantic Hurricane Season. Research teams successfully collected valuable wind and wave data during the passage of Hurricane Ike. A TTU StickNet platform obtained wind measurements in true marine exposure with a fetch across the Houston ship channel, and three UF/UND wave gauges collected shoaling wave data adjacent to landfall. Findings indicated that the drag coefficient reached a limiting value at wind speeds near hurricane force; in relative agreement with deep water measurements reported in [1]. At slower wind speeds the drag coefficient was higher than over deep water. This suggests that storm surge models may require separate forcing parameterizations in such complex wave/bathymetric conditions. Coastal roughness lengths provide evidence that Exposure D should be prescribed by ASCE along the hurricane prone coastline.