Comparison of winds, waves, and turbulence as observed by airborne lidar, ground-based radars, and instrumented tower


  • M. D. Eilts,

  • R. J. Doviak,

  • A. Sundara-Rajan


On June 29, 1981, two ground-based Doppler radars, an airborne Doppler lidar, a tall (444 m) instrumented tower, and a rawinsonde collected wind data in the planetary boundary layer (PBL) in central Oklahoma. This allowed, for the first time, intercomparison of wind fields synthesized from airborne Doppler lidar data with those from dual Doppler radar data. The vertical profile of wind in the PBL measured by the radars compared favorably with the profiles measured by the tower and rawinsonde while the one obtained from lidar data differed from the other three by as much as 3 m/s in wind speed and 38° in direction. The time dependence of differences in wind estimates from radar and lidar suggested that these discrepancies could be attributed to a Schuler resonance in the aircraft's inertial navigation system which caused an erroneous component of the aircraft velocity vector to be subtracted from the lidar radial velocities, thus creating errors in the synthesized wind speed and direction. The vertical profiles of horizontal velocity fluctuations detected by the different sensing systems compared well. Also, spectra from the different sensing systems compared well in both magnitude and shape, suggesting that the lidar and radar detected similar structure in the PBL. A peak at the 4-km wavelength, evident in spectra from all sensing systems, is proposed to be caused by horizontally symmetrical cells having a wavelength 4 times the height of the PBL in accord with theory.