Tropical cyclone boundary layer wind variability

The design of buildings and other structures in tropical cyclone prone areas must consider fundamental estimates of design wind speeds, the variation of wind loads with height, and local effects due to accelerated flow. Until recently, very few wind profile observations were available to provide the basis for vertical wind load variation in tropical cyclones. Major considerations that require investigation include: 1) What is the mean wind profile in the lowest 500 m of a tropical cyclone and how much does it vary as the mean wind speed changes? 2) Are the observed multiple low -level wind maxima localized effects which are already adequately covered by the safety factors used in design? 3) Are these features common to all hurricanes or only the most intense? 4) Are gust factors in tropical cyclones similar to those found in mid-latitude systems with similar exposures? The past 3 years of GPS sonde field measurements have provided a preliminary statistical basis to help answer these questions. While exploring these questions we will also assess the ability of similarity theory based models to estimate surface winds and fluxes from mean boundary layer quantities.