15th Conference on Boundary Layer and Turbulence


Coherence of vertical velocity from a zenith-pointing Doppler lidar

Shane D. Mayor, NCAR, Boulder, CO; and D. H. Lenschow

We utilize the capability of a zenith-pointing Doppler lidar to measure vertical velocity coherence in the convective boundary layer (CBL). The High Resolution Doppler Lidar (HRDL), developed by NOAA Environmental Technology Laboratory, operates at 2 microns wavelength to detect the mean radial velocity of aerosol particles. The vertical coherence is a measure of the correlation between vertical velocity, w, at various separation distances as a function of height above the ground and of frequency or, by using mean wind measurements, of wavenumber. The lidar operated continuously in this mode on thirteen days during the summer of 1996 in the Lidars in Flat Terrain (LIFT) experiment over level farmland in central Illinois. The lidar measured w with 30 m vertical resolution over a period of 1-10 s depending on the return signal strength which varied from day to day. Other concurrent measurements included boundary-layer height from an aerosol lidar, wind and thermodynamic profiles from a radar profiler and radiosondes, and surface meteorological conditions. In at least two cases, aerosol scattering from the overlying free atmosphere was sufficient to measure w simultaneously above and below the PBL top.

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Poster Session 1, Cloudy and Convective BLs
Monday, 15 July 2002, 2:00 PM-2:00 PM

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