Continuous monitoring of the boundary-layer top with lidar

H. Baars (1) , A. Ansmann (1) , R. Engelmann (1) , D. Althausen (1)

1 TROPOS - Leibniz Institute for Tropospheric Research

Continuous lidar observations of the top height of the boundary layer (BL top) have been performed at Leipzig (51.3° N, 12.4° E), Germany, since August 2005. The results of measurements taken with a compact, automated Raman lidar over a one-year period (February 2006 to January 2007) are presented. Four different methods for the determination of the BL top are discussed. The most promising technique, the wavelet covariance algorithm, is improved by implementing some modifications so that an automated, robust retrieval of BL depths from lidar data is possible. Three case studies of simultaneous observations with the Raman lidar, a vertical-wind Doppler lidar, and accompanying radiosonde profiling of temperature and humidity are discussed to demonstrate the potential and the limits of the four lidar techniques at different aerosol and meteorological conditions. The lidar-derived BL top heights are compared with respective values derived from predictions of the regional weather forecast model COSMO of the German Meteorological Service. The comparison shows a general underestimation of the BL top by about 20% by the model. The statistical analysis of the one-year data set reveals that the seasonal mean of the daytime maximum BL top is 1400 m in spring, 1800 m in summer, 1200 m in autumn, and 800 m in winter at the continental, central European site. BL top typically increases by 100?300 m per hour in the morning of convective days.

Domaines: Océan, Atmosphère

H. Baars, A. Ansmann, R. Engelmann, D. Althausen. Continuous monitoring of the boundary-layer top with lidar. Atmospheric Chemistry and Physics Discussions, 2008, 8 (3), pp.10749-10790. ⟨hal-00304231⟩