Calculation of the overlap factor for scanning LiDAR based on the tridimensional ray-tracing method

UAVC: A New Method for Correcting Lidar Overlap Factors Based on Unmanned Aerial Vehicle Vertical Detection

A method to calibrate the overlap factor of Lidar is proposed, named unmanned aerial vehicle correction (UAVC), which uses unmanned aerial vehicles (UAVs) to detect the vertical distribution of particle concentrations. The conversion relationship between the particulate matter concentration and the aerosol extinction coefficient is inverted by the high-altitude coincidence of the vertical detection profiles of the UAV and Lidar. Using this conversion relationship, the Lidar signal without the influence of the overlap factor can be inverted. Then, the overlap factor profile is obtained by comparing the signal with the original Lidar signal. A 355 nm Raman-Mie Lidar and UAV were used to measure overlap factors under different weather conditions. After comparison with the Raman method, it is found that the overlap factors calculated by the two methods are in good agreement. The changing trend of the extinction coefficient at each height is relatively consistent, after comparing the inversion result of the corrected Lidar signal with the ground data. The results show that after the continuously measured Lidar signal is corrected by the overlap factor measured by this method, low-altitude aerosol information can be effectively obtained.

Incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS)-based strategy for direct measurement of aerosol extinction in a lidar blind zone

In this Letter, the development of a custom-designed incoherent broadband cavity enhanced absorption spectrometer (IBBCEAS) and its application to in situ measurement of aerosol extinction near the ground surface are described in an effort to address the issue of missing data in the light detection and ranging (lidar) blind zone in the first hundreds of meters of the observation range. Combined measurements of aerosol extinction at the same location using lidar remote sensing at 355 nm and in situ IBBCEAS operating in the UV spectral region around 370 nm showed results with a good correlation (${{\rm R}^2} = {0.90}$R²=0.90) between the two measurement techniques. This Letter highlights a new strategy for near-end lidar calibration, using a ground-based compact and robust IBBCEAS located at the lidar measurement site to determine the vertical profile of the aerosol extinction coefficient with a higher accuracy.