Lidar observation of the nocturnal boundary layer formation over Sofia, Bulgaria

Lidar and Sun photometer observations of atmospheric boundary-layer characteristics over an urban area in a mountain valley

“…Lidar specifications: transmitter -a standard Nd-YAG laser (operational wavelength 532 nm, pulse duration and energy 15-20 ns and 10-15 mJ, repetition rate 12.5 Hz); receiving antenna -a Cassegrainian telescope (main mirror diameter 150 mm, equivalent focal length 2250 mm); photodetector -a photomultiplier aligned with an interference filter (1 nm FWHM); data acquisition and processing set -a 10-bit 20 MHz analog-to-digital converter and a PC (Kolev et al 2000).…”

“…Thus, heights of the different layers (and/or of their boundaries), particularly that of the mixing one, could be determined using different methods, e.g. following the standard deviation of the S-function (see below), calculating the first and second derivatives of the latter (Menut et al 1999;Kolev et al 2000). The mixing-layer height in these experiments was determined following the so-called gradient method (Sasano et al 1982).…”

“…A number of studies have focused on the comparison between lidar and conventional measurements; the lidar technique being considered suitable for estimating the mixing-layer height involving various methods, e.g. using the standard deviation of the S-function (see later), and its first and second derivatives (Sasano et al 1982;Menut et al 1999;Kolev et al 2000), etc. The first elaborate lidar investigations of the entire atmospheric boundary layer (ABL) were carried out by Coulter (1979).…”

“…the so-called entrainment zone. Recently, the lidar observations were directed to studies of the residual layer and its interaction with the mixing layer (Kolev et al 2000;Fochesatto et al 2001). Other types of lidar investigation were oriented to determining the aerosol optical characteristics in the ABL, whereby the lidar soundings were accompanied by radiometer and/or sun photometer measurements.…”

Observational studies of the meteorological characteristics associated with poor air quality over the Pearl River Delta in China

“…Data from tethered balloon observations show that light wind and lower inversion at nighttime in urban areas are important factors that contribute to poor air quality (Kolev et al, 2000;Sang et al, 2000). Weak and intermittent turbulence in nocturnal ABL and the temporary turbulent coupling of the residual layer to the surface layer facilitate the transport of pollutants, which are stored aloft over the surface (Pournazeri et al, 2012;Salmond andMcKendry, 2002, Day et al, 2010).…”