Continuous monitoring of the boundary-layer top with lidar

Abstract

Abstract. 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.

Performance Evaluation of the Boundary-Layer Height from Lidar and the Weather Research and Forecasting Model at an Urban Coastal Site in the North-East Iberian Peninsula

“…The general approach is to employ the Haar wavelet function to extract scale-dependent information from the original lidar range-corrected signal profile; this detects step changes in the range-corrected signal. The WCT method has been used in many previous studies (Baars et al 2008;Gan et al 2011) and has proven to be a computationally robust technique.…”

“…To recall, the dilation parameter is the vertical extent of the step function. Baars et al (2008) introduced a modified version of the WCT method in an attempt to find an appropriate dilation dependent on the atmospheric situation. For this study, a series of dilation values have been tested with the Barcelona lidar data.…”

“…They comprise both objective and subjective methods: objective methods consist of various forms of derivative methods (Flamant et al 1997;Sicard et al 2006Sicard et al , 2011, wavelet analysis methods (Baars et al 2008;Gan et al 2011), the threshold method (Melfi et al 1985;Boers and Eloranta 2006), and the variance method (Menut et al 1999;Hennemuth and Lammert 2006). Visual inspection methods (Quan et al 2013) are infrequently used as a subjective approach, which adds levels of ambiguity that may possibly lead to poor results.…”

Continuous 1064/532 nm Lidar Measurements (CORALNet-UBC) in Vancouver, British Columbia: Selected Results from a Year of Operation

“…Application of ground-based, upward-pointing lidar to the continuous observation of the lower atmosphere has become increasingly common and sophisticated in recent years (Mattis et al, 2008;Morille et al, 2007;Baars et al, 2008;Rauthe et al, 2008). Rich datasets produced by these systems provide opportunities to study myriad phenomena at a range of scales.…”

“…Rich datasets produced by these systems provide opportunities to study myriad phenomena at a range of scales. Examples include the detection of boundary layer height and structure (Baars et al, 2008;Brooks et al, 2003;McKendry et al, 2009;Morille et al, 2007;Steyn et al, 1999) and cloud base (Morille et al, 2007;Pal et al, 1992;Wang and Sassen, 2001) and, with Raman Lidar, the structure of frontal systems (Melfi et al, 1989;Sakai et al, 2005) and gravity waves (Rauth et al, 2008). Lidar can also *Corresponding author's e-mail: ian.mckendry@geog.ubc.ca elucidate singular events such as dust storms, biomass burning plumes and even firework plumes (Müller et al, 2005;van der Kamp et al, 2008;Tratt et al, 2001;Murayama et al, 2001).…”