TPSAS-NF1676L-31882-DND

Abstract

Lidar ratios are required to retrieve the extinction profiles in CALIOP algorithm. Unconstrained retrievals: A default lidar ratio is used depending upon the aerosol subtype. Constrained retrievals: The lidar ratio (S) is retrieved from the measured two way transmittance (T2), when clear air is found both above and below the layer for at least 2.5 km (T^2 = / ; S = (1-T2)/2γ’), where and are the mean attenuated scattering ratios below and above the layer respectively, and γ’ is the layer integrated attenuated backscatter. A multiple scattering factor of 1 is assumed. In general, constrained lidar ratios are expected to be more representative (but also noisier) than the unconstrained cases, hence accuracy of the unconstrained lidar ratios can be assessed using the constrained ones.