Comparison studies of the Scheimpflug lidar technique and the pulsed lidar technique for atmospheric aerosol sensing

The Scheimpflug lidar (SLidar) technique has been recently developed for various remote sensing applications, where the lidar signal is detected by an image sensor according to the Scheimpflug principle instead of the time-of-flight principle. Comparison studies between the SLidar technique and the conventional pulsed lidar technique are crucial for understanding the principle as well as the measurement results of the SLidar technique. In this work, a 520-nm Scheimpflug lidar system and a 532-nm pulsed lidar system have been developed for comparison studies. Atmospheric remote measurements as well as statistical analysis have been carried out on a near horizontal path and on a slant direction with an elevation angle of 30°. The temporal-spatial variations of the atmospheric backscattering maps measured by the 520-nm SLidar system and the 532-nm pulsed lidar system generally agreed well. The median extinction coefficient measured by the SLidar and the pulsed techniques has shown similar temporal evolution during the near-horizontal comparison study, and a correlation coefficient of 0.99 has been achieved through statistical analysis on all lidar measurements. Moreover, the root mean square error (RMSE) ratio for each extinction coefficient profiles has also been evaluated, and the mean value of the RMSE ratio for all lidar measurements was about 11% in homogeneous atmospheric conditions. During slant comparison studies, the RMSE ratio between the SLidar curve and the pulsed lidar curve was less than 5% in the region of 0.5-2 km, and it generally increased with the increasing of the measurement distance primarily due to the decreased range resolution of the SLidar technique. The promising results suggested that the SLidar technique, featuring of short blind range, could be suitable for aerosol sensing particularly in the planetary boundary layer.