Abstract
We utilized a Doppler lidar to measure integral scale and coherence of vertical velocity w in the daytime convective boundary layer (CBL). The high resolution 2 μm wavelength Doppler lidar developed by the NOAA Environmental Technology Laboratory was used to detect the mean radial velocity of aerosol particles. It operated continuously in the zenith-pointing mode for several days in the summer 1996 during the “Lidars in Flat Terrain” experiment over level farmland in central Illinois. We calculated profiles of w integral scales in both the alongwind and vertical directions from about 390 m height to the CBL top. In the middle of the mixed layer we found, from the ratio of the w integral scale in the vertical to that in the horizontal direction, that the w eddies are squashed by a factor of about 0.65 as compared to what would be the case for isotropic turbulence. Furthermore, there is a significant decrease of the vertical integral scale with height. The integral scale profiles and vertical coherence show that vertical velocity fluctuations in the CBL have a predictable anisotropic structure. We found no significant tilt of the thermal structures with height in the middle part of the CBL.
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The National Center for Atmospheric Research is sponsored by the National Science Foundation.
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Lothon, M., Lenschow, D.H. & Mayor, S.D. Coherence and Scale of Vertical Velocity in the Convective Boundary Layer from a Doppler Lidar. Boundary-Layer Meteorol 121, 521–536 (2006). https://doi.org/10.1007/s10546-006-9077-1
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DOI: https://doi.org/10.1007/s10546-006-9077-1