ARL News

Urban Testbed Program Gaining Momentum


November 8, 2004

During the past hurricane season, there were two deployments of the ARL “Best Available Turbulence” (BAT) probe on the NOAA P3 N43RF, to obtain measurements of winds and turbulence in the hurricane boundary layer. In early September, N43RF was deployed to Barbados to fly through Hurricane Frances as the storm passed north of St. Croix on its westward track. Several passes were made through the periphery of the storm, at 1500 ft above the surface. Data collected on these passes will be used to characterize the transfer of energy through the top of the boundary layer. For Hurricane Jeanne, N43RF deployed out of MacDill AFB and made several low-level runs. Unfortunately the structure of Jeanne did not allow for repeated flux runs at low levels, so data collected in this storm are marginal at best. These two deployments underscore the necessity for a long-range plan to attain a series of measurements in hurricanes over a number of years. Despite the setbacks related to storm structure and flight patterns, the instrumentation performed well.

The ARL surface-mounted Extreme Turbulence (ET) probes also enjoyed several successful deployments. During Hurricane Frances, three probes were set up. Two different configurations were tested. Wind speed and direction were determined 50 times per second by sampling the distribution of pressure over 400 mm diameter spheres.

Two ET probes were set up for hurricane Ivan. Both probes recorded data throughout the storm. Preliminary analysis indicates that the three-component velocity sensors resolve turbulence well into the inertial subrange, permitting accurate computation of surface stress.

ARL hurricane turbulence research is a joint activity of the ARL Divisions in Idaho Falls, ID, and Oak Ridge, TN. The work is mainly sponsored by the Navy.

Contact information: Bruce B. Hicks
Phone: (301) 713-0684