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Boundary-Layer Meteorology

, Volume 121, Issue 3, pp 521–536 | Cite as

Coherence and Scale of Vertical Velocity in the Convective Boundary Layer from a Doppler Lidar

  • Marie Lothon
  • Donald H. Lenschow
  • Shane D. Mayor
Original Article

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.

Keywords

Coherence Convective boundary layer Integral scale Lidar Turbulence 

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Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  • Marie Lothon
    • 1
    • 2
  • Donald H. Lenschow
    • 1
  • Shane D. Mayor
    • 1
  1. 1.National Center for Atmospheric ResearchBoulderUSA
  2. 2.Laboratoire d’Aérologie, ToulouseCNRS, Centre de Recherches AtmosphériquesCampistrousFrance

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