Wind profile observations in tropical cyclone events using wind-profilers and doppler SODARs

Since the mean wind profile in the tropical cyclone boundary layer is important in both the fields of meteorology and wind engineering, the wind measurements taken during the passages of several tropical cyclones or typhoons in Hong Kong by the wind-profilers and the Doppler Sonic Detection And Ranging (SODAR) have been utilized to calculate both the hourly and 10-min mean wind profiles. These observed profiles were then fitted to the log-law, the power-law and an empirical profile model taking into consideration the low-level jet. The results showed that the low-level jet, which is commonly observed for the mean wind profile in the tropical cyclone boundary layer over the sea, was not found. In addition, we found that the surface roughness derived by fitting the observed profile to the log-law was unusually high (_z0 > 1.5 m). The possible explanations include (1) the influence of large scale topography and (2) the high waves introduced by strong typhoon winds.