Lidar estimation of tropospheric aerosol extinction, surface area and volume: Maritime and desert-dust cases

A numerical model, based on a Monte Carlo approach, is presented to determi ne functional relationships linking backscatter and other important propert ies as extinction, surface area, and volume of tropospheric aerosols. If ex isting, such relationships allow for a direct estimate of such properties b y means of a single-wavelength lidar measurement. To be employed in a lidar inversion procedure, the extinction to backscatter ratio is also analyzed. Maritime and desert dust aerosol particles are addressed. In the latter ca se, both spherical and nonspherical shape of particles are considered. Larg e differences (up to 200%) result from the comparison of extinction compute d for spherical and nonspherical particles. On the whole, maximum errors to be associated to the model estimation of the aerosol extinction coefficien t and surface area are of the order of 50%. Conversely, errors associated t o volume estimates range from 15% to 100%. To validate the model, a first c omparison is performed between lidar and Sun-photometer-derived aerosol opt ical thickness of both maritime aerosols and Saharan dust.