Wednesday, 12 February 2003: 8:30 AM
Turbulence dissipation rate measured by 915 MHz wind profiling radars compared with in-situ tower and aircraft data
In this paper we present a comparison of the dissipation rate of turbulence kinetic energy derived from several 915 MHz wind profiling radars with dissipation measured at 120 m on a tower at the Hanford Meteorological Station (HMS) in southeastern Washington and measured with aircraft as part of the CASES-97 field measurement program. The wind profiler data have been processed using the NCAR Improved Moment Algorithm (NIMA) to automate the selection of Doppler spectral moments over many beam cycles. Broadening of the Doppler spectrum due to non-turbulent effects has been removed using recently published techniques. Profiles of dissipation rate for comparison from the CASES-97 were constructed using profiler values corresponding to the times and heights of O(10 min) aircraft flight legs. Aircraft values of dissipation rate were derived using the inertial subrange of the longitudinal component of wind velocity. Profiles from the radar and the aircraft show encouraging agreement. Data from lowest range gates of the PNNL radar at HMS were compared over four diurnal cycles during a pre-field system evaluation in April 2000. The agreement over the diurnal period is good. The stability of successive 5-minute measurements from the profiler suggests that the combination of NCAR's Improved Moment Algorithm with recent techniques for accounting for non-turbulent broadening of spectral peaks provides an effective means of obtained the dissipation structure of the boundary layer with high temporal resolution.