Monday, 10 February 2003
A comparison of winds measured by a 915 MHz wind profiling radar and a Doppler lidar
During October 2000, a field program was executed in the Salt Lake Valley in support of the U.S. Department of Energy's program to study vertical mixing processes in urban valleys and basins. Instrumentation deployed in this program included NOAA's Doppler lidar system and several 915 MHz wind profilers, one of which was operated by PNNL in the central Salt Lake Valley. In processing data from the PNNL radar we have used the recently developed NCAR Improved Moment Algorithm (NIMA), which uses fuzzy logic and pattern recognition to simulate spectral peak selection that would be done by a human expert. Wind profiles derived from the profiler using the NIMA are qualitatively stable for successive cycles through the profiler's five beams. In this paper, we compare consensus mean wind profiles from the NIMA-processed profiler data with those constructed over 30 min from VAD scans of the Doppler lidar. The results show very good agreement between the two systems. In a more stringent test of the NIMA, we also compare projections of profiler's 5-min. wind profiles onto the lidar RHI scan direction with the lidar's radial velocity profiles at the lidar range gate corresponding to the profiler location. This was done using data from RHI scans that were directed toward the profiler for purposes of this comparison.
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