Abstract

Abstract. In this paper, a new elastic lidar inversion equation is presented. It is based on the backscattering signal from a surface reference target (SRT) rather than that from a volumetric layer of reference (Rayleigh molecular scatterer) as is usually done. The method presented can be used when the optical properties of such a layer are not available, e.g., in the case of airborne elastic lidar measurements or when the lidar–target line is horizontal Also, a new algorithm is described to retrieve the lidar ratio and the backscattering coefficient of an aerosol plume without any a priori assumptions about the plume. In addition, our algorithm allows a determination of the instrumental constant. This algorithm is theoretically tested, viz. by means of simulated lidar profiles and then using real measurements. Good agreement with available data in the literature has been found.

Highlights

  • Atmospheric aerosols are liquid or solid particles dispersed in the air (Glickman and Zenk, 2000) of natural or anthropogenic origins

  • A fourth method consists of the determination of the optical thickness and lidar ratio of transparent layers located above opaque clouds (Hu et al, 2007; Young, 1995) that are used as reference for calibration in the inversion procedure (O’Connor et al, 2004)

  • A new method has been introduced for lidar measurement inversion in a situation for which a volumetric layer of the high troposphere is not available

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Summary

Introduction

Atmospheric aerosols are liquid or solid particles dispersed in the air (Glickman and Zenk, 2000) of natural (volcano, biomass burnings, desert, ocean) or anthropogenic origins. A fourth method consists of the determination of the optical thickness and lidar ratio of transparent layers located above opaque clouds (Hu et al, 2007; Young, 1995) that are used as reference for calibration in the inversion procedure (O’Connor et al, 2004). A fifth approach consists of the determination of the optical thickness of the atmosphere from the sea surface echo by combining lidar and radar measurements (Josset et al, 2010a, b, 2008) This method has been used to find the lidar ratio and the optical depth of aerosol layers over oceans (Dawson et al, 2015; Josset et al, 2012; Painemal et al, 2019). A discussion and a conclusion follow and close the present paper

Unified lidar equation for surface and volumetric scattering media
Radiative parameters identification
Determination of LRa and βa: methodology
Theoretical lidar signals
Noise impact on βa and LRa retrievals
Case of real measurements
Description of the experimental operations
Optical property retrieval: fog-oil plume
Findings
Conclusions

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