Broadband continuous-wave differential absorption lidar for atmospheric remote sensing of water vapor

Abstract

What we believe to be a novel low-cost broadband continuous-wave water vapor differential absorption lidar (CW-DIAL) technique has been proposed and implemented by combing the Scheimpflug principle and the differential absorption method. The broadband CW-DIAL technique utilizes an 830-nm high-power multimode laser diode with 3-W output power as a tunable light source and a CMOS image sensor tilted at 45° as the detector. A retrieval algorithm dedicated for the broadband CW-DIAL technique has been developed to obtain range-resolved water vapor concentration from the DIAL signal. Atmospheric remote sensing of water vapor has been carried out on a near-horizontal water vapor path to validate the performance of the broadband CW-DIAL system. The retrieved water vapor concentration showed a good consistency with those measured by an air quality monitoring station, with a correlation coefficient of 0.9669. The fitting error of the water vapor concentration is found to be less than 10%. Numerical simulation studies have revealed that the aerosol-induced error on the water vapor concentration is below 5% with a background water vapor concentration of 5 g/m3 for most atmospheric conditions. The experimental results have successfully demonstrated the feasibility of the present broadband CW-DIAL technique for range-resolved water vapor remote sensing.

An Appraisal of the Progress in Utilizing Radiosondes and Satellites for Monitoring Upper Air Temperature Profiles

“…Lidar systems use laser pulses to probe the atmosphere, and the Raman lidar specifically employs Raman scattering to obtain information about the composition and structure of the atmosphere [101]. On the other hand, differential absorption lidars (DIALs) are remote sensing instruments used to measure the concentration of trace gases and aerosols in the atmosphere [102]. They employ the principle of laser-induced absorption spectroscopy to detect specific molecules by measuring the absorption of laser light at particular This suggests that the number of papers on the remote sensing of upper air temperature has progressively increased over time, and thematic evolution has been ongoing since the introduction of satellites in the 1960s for different meteorological applications [33].…”

“…On the other hand, differential absorption lidars (DIALs) are remote sensing instruments used to measure the concentration of trace gases and aerosols in the atmosphere [102]. They employ the principle of laser-induced absorption spectroscopy to detect specific molecules by measuring the absorption of laser light at particular wavelengths [102]. DIALs operate by transmitting two laser beams, typically referred to as the "on-line" and "off-line" wavelengths, into the atmosphere [102].…”

“…They employ the principle of laser-induced absorption spectroscopy to detect specific molecules by measuring the absorption of laser light at particular wavelengths [102]. DIALs operate by transmitting two laser beams, typically referred to as the "on-line" and "off-line" wavelengths, into the atmosphere [102]. Meanwhile, a radio acoustic sounding system (RASS) is a remote sensing instrument designed to measure vertical profiles of the temperature and wind speed in the atmosphere [103].…”