Application of a multiple scattering model to estimate optical depth, lidar ratio and ice crystal effective radius of cirrus clouds observed with lidar.

D A Gouveia ,Ulla Wandinger,Paulo Artaxo,Patric Seifert,Eduardo Landulfo,Albert Ansmann,Holger Baars,Boris Barja,H M Barbosa ,Fábio Lopes

doi:10.1051/epjconf/201817605037

Abstract

Lidar measurements of cirrus clouds are highly influenced by multiple scattering (MS). We therefore developed an iterative approach to correct elastic backscatter lidar signals for multiple scattering to obtain best estimates of single-scattering cloud optical depth and lidar ratio as well as of the ice crystal effective radius. The approach is based on the exploration of the effect of MS on the molecular backscatter signal returned from above cloud top.

Highlights

It is well known that measurements with lidar are highly influenced by multiple scattering effects, where a substantial fraction of the photons scattered in the forward direction remains close to the receiver field of view (RFOV) where they are subject to subsequent scattering events until they are detected by the system [4]
This generates a narrow diffraction peak that remains within the RFOV, and can change the molecular signal measured by the lidar far above the top of the cloud [5]
We present an iterative approach to obtain the optical depth and average lidar ratio of cirrus clouds corrected for the effects of multiple scattering using the elastic backscatter signal, for the case that there is information about the size of the ice crystals as well as errors associated

Summary

INTRODUCTION

Lidar systems are an indispensable tool in remote sensing of macro and microphysical properties of cirrus clouds, especially considering optically thin clouds (COD

Multiple Scattering In Cirrus

Correction for Multiple Scattering

Effective Radius

Findings

CONCLUSIONS