Experimental Calibration of the Overlap Factor for the Pulsed Atmospheric Lidar by Employing a Collocated Scheimpflug Lidar

Abstract

Lidar techniques have been widely employed for atmospheric remote sensing during past decades. However, an important drawback of the traditional atmospheric pulsed lidar technique is the large blind range, typically hundreds of meters, due to incomplete overlap between the transmitter and the receiver, etc. The large blind range prevents the successful retrieval of the near-ground aerosol profile, which is of great significance for both meteorological studies and environmental monitoring. In this work, we have demonstrated a new experimental approach to calibrate the overlap factor of the Mie-scattering pulsed lidar system by employing a collocated Scheimpflug lidar (SLidar) system. A calibration method of the overlap factor has been proposed and evaluated with lidar data measured in different ranges. The overlap factor, experimentally determined by the collocated SLidar system, has also been validated through horizontal comparison measurements. It has been found out that the median overlap factor evaluated by the proposed method agreed very well with the overlap factor obtained by the linear fitting approach with the assumption of homogeneous atmospheric conditions, and the discrepancy was generally less than 10%. Meanwhile, simultaneous measurements employing the SLidar system and the pulsed lidar system have been carried out to extend the measurement range of lidar techniques by gluing the lidar curves measured by the two systems. The profile of the aerosol extinction coefficient from the near surface at around 90 m up to 28 km can be well resolved in a slant measurement geometry during nighttime. This work has demonstrated a great potential of employing the SLidar technique for the calibration of the overlap factor and the extension of the measurement range for pulsed lidar techniques.

Vertical Structure of Dust Aerosols Observed by a Ground-Based Raman Lidar with Polarization Capabilities in the Center of the Taklimakan Desert

“…Photon counting mode was employed at wavelengths of 387, 407, and 607 nm with a vertical resolution of 7.5 m, while both photon counting and analog modes were used at wavelengths of 532 and 355 nm with a vertical resolution of 3.75 m. The observed data has a temporal resolution of 3 min. Original signals were pre-processed by background subtraction, photon-counting signal dead-time correction, and overlap correction [40,41]. Then, the lidar polarization calibration ratio (K) and the lidar system constant (C) are calculated for each wavelength [36].…”

Development of a versatile lidar system based on passively Q-switched Nd: YAG laser for monitoring aerosols and cirrus clouds in the atmosphere

“…We assume that in the entire horizontal range, the medium is homogeneous [8,19,34,35]. The backscatter coefficient β and extinction coefficient ρ are considered constant in all range of lidar signals.…”

Research on near-surface water vapor detection method based on scanning continuous light

“…However, this technology has limitations and cannot provide near-surface detection information. The Scheimpflug imaging lidar is compact enough to overcome the problem of detecting blind zones [8] . However, its detection range and sensitivity are not as good as those of narrow-pulse backscatter lidar when performing water vapor detection because the image sensor sensitivity is not yet ideal.…”