Doppler profiler observations of Hurricane Georges at landfall

Abstract

The boundary layer (BL) within the western eyewall of Hurricane Georges, during its landfall on the Missisippi coastline, is described using measurements from a mobile Doppler profiling system. The turbulent layer depth, roughly proportional to the BL wind magnitude, attained a height of about 2 km above ground level (AGL) during maximum measured winds of 40-45 m s -1 near 0.5 km altitude. The BL contains updrafts and downdrafts of 1-3 m s -1 magnitude that may be associated with the vertical branches of horizontal convective rolls or wind streaks recently identified within landfalling hurricanes. These turbulent eddies, and the large vertical shear of horizontal winds within the BL above and below the jet maximum within the eyewall, appear to produce a uniform mass concentration of relatively small raindrops within the BL.