The 13th Symposium on Boundary Layers and Turbulence

P2B.17
BOUNDARY LAYER WIND CHARACTERISTICS UNDER HIGH WIND CONDITIONS

A Savtchenko, RSMAS/Univ. of Miami, Miami, FL; and B. Albrecht, T. Faber, F. Marks, P. Black, and A. White

Strong easterly flow was observed in coastal areas of South Florida and the Keys during a 5-day period in November 1996. This flow was associated with a strong high pressure (~ 1045 mb) over the northwest US and a persistent trough over the Caribbean Sea. A 915 MHz wind profiler operating in the Miami Florida area (about 15 km inland) during this time was used to measure winds from 120 to 4000 meters at 2-3 minute intervals during the entire wind event. During this period a strong jet with speeds as high as 28 m/s was observed at a height of 1 km. A capping inversion varying from 2-3 km was generally well defined by the signal-to-noise ratios from the profiler. Stratocumulus clouds extended from about 500 m to the capping inversion with
occasional periods of drizzle observed at the profiler site. Winds at the core of the jet are relatively steady compared with those below this level. Fluctuations in the winds at the profiler site, show a relatively weak correlation between the jet-core winds and those at 120-200 m. Episodic vertical mixing events, however, give rise to large fluctuation in the winds at the lower levels. The analyses focus on a 48-hour period of strongest winds. VAD scans made at 6-minute intervals are available from the Miami WSR-88D during 30 minutes of this 48-hour period. These scans show bands of shallow convection by 30-40 km that move oblique to the mean wind direction at approximately the speed of the low-level jet. Satellite images confirm the presence of these bands at times throughout the highest wind conditions. The possibility that these bands are associated with ducted gravity waves is currently being investigated using the horizontal and vertical winds from the profiler and the VAD scans from the WSR-88D

The 13th Symposium on Boundary Layers and Turbulence