Remote sensing of atmospheric gases with optical correlation spectroscopy and lidar: first experimental results on water vapor profile measurements

Abstract

In this paper, the first experimental demonstration of the optical correlation spectroscopy lidar (OCS-lidar) is proposed. It is a new active remote sensing methodology to measure range-resolved atmospheric gas concentrations, based on broadband laser spectroscopy and light amplitude modulation. As a first step, a numerical study is performed for OCS-lidar measurements to optimize the accuracy of the range-resolved gas concentration measurement. Then, we demonstrate the ability of the OCS-lidar methodology to monitor the water vapor in the planetary boundary layer using the 4m 720-nm absorption band. In addition to this first experimental proof, two different experimental configurations are proposed. The amplitude modulation, related to the optical correlation spectroscopy, is operated either at the emission with an active amplitude modulator before the backscattering process, or with passive optical filters on the laser backscattered light. For both configurations, range-resolved gas concentration measurements, achieved with a micro-pulse ground-based OCS-lidar, are presented. An extended discussion presents the mixing-ratio accuracy, which reaches ±1,000 ppm at a 2,000-m range for a range resolution of 200 m. The differences between the two experimental configurations are also discussed.

Remote Sensing of Greenhouse Gases by Combining Lidar and Optical Correlation Spectroscopy

“…Water Vapor The first experimental proof of OCS-Lidar has been performed on the measurement of the water vapor content in the PBL [5]. We also demonstrate the ability to realize the experiment using two different configurations of M i (see Eq.…”

“…From the ratio of OCSLidar signals P C (r) and P NC (r), we retrieved an analytical expression of [TG](r) by approximating the TG transmission present in T(r,λ) with a Taylor expansion series of the Lambert Beer equation. The mathematical description can be found elsewhere [5].…”

“…We have recently developed the OCS-Lidar, a novel instrument that is based on coupling a Lidar with Optical Correlation Spectroscopy (OCS). Its principle and the theoretical approach have then been established [5] leading to a comprehensive study on OCS-Lidar errors budget in the NIR [6]. Moreover OCS-Lidar based on a femtosecond broadband laser source has been successfully applied to retrieve water vapor in the lower atmosphere using the 4ν 720 nm absorption band [5].…”

Design of compact joint transform correlator

“…fast parallel processing, large capacity and high speed, and can also be programmed conveniently. JTCs have been widely used in the image recognition and target detection [3][4][5]. In the present study, we use a JTC to measure the image shifts.…”

The Carbon Aerosol / Particles Nucleation with a Lidar: Numerical Simulations and Field Studies

“…Recent advances in lidar concern both atmospheric traces [4] and aerosols up to threecomponent particle mixtures involving volcanic ash, desert dust, sea-salt or sulfate particles [5]. However, up to now to our knowledge, no lidar methodology exists that allows a range-resolved specific detection of the carbon aerosol in the atmosphere over several hundreds of meters, despite its key role on human health, as being carcinogenic in urban polluted areas [6], and in radiative forcing, black carbon being the second contributor to global warming after CO2 [7].…”