Impact of cirrus cloud ice crystal shape and size on multiple scattering effects: application to spaceborne and airborne backscatter lidar measurements during LITE mission and E LITE campaign

Forward scattering in cirrus clouds can significantly affect backscatter li dar signal. Its contribution can be estimated numerically knowing the size and shape of the crystals. Contemporary airborne and space-borne lidar meas urements collected during the European Lidar In-space Technology Experiment (E-LITE) field campaign tin the framework of the NASA/LITE mission) are us ed to show that forward scattering reduces the optical depth derived from s pace-borne measurements by at least a factor of 2 with respect to the true value. This reduction factor is discussed iri terms of crystal size and sha pe (i.e. forward scattering, and measurement configuration). It is shown th at cirrus backscatter-to-extinction ratios derived from airborne and space- borne lidar measurements can be used to illustrate the sensitivity of multi ple scattering effects the ice crystal size and shape.