LIDAR EFFECTIVE MULTIPLE-SCATTERING COEFFICIENTS IN CIRRUS CLOUDS

We delimit a regime, valid for most ground-based lidar probings of cir rus clouds, in which the field-of-view dependence of multiple scatteri ng reaches a plateau. In this regime and assuming the phase function t o be constant around pi, we formally demonstrate Platt's modification of the single-scattering lidar equation, with a parameter eta(p), acco unting for the reduction of the effective scattering coefficient defin ed so that (1 - eta(p)) is the amount of energy scattered in the forwa rd peak. Then, to cope with nonconstant backscattering functions, we d iscuss the introduction of an effective backscattering coefficient tha t is an average of the scattering probabilities around pi. (C) 1997 Op tical Society of America.