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 determine functional relationships linking backscatter and other important properties as extinction, surface area, and volume of tropospheric aerosols. If existing, such relationships allow for a direct estimate of such properties by 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 case, both spherical and nonspherical shape of particles are considered. Large differences (up to 200%) result from the comparison of extinction computed for spherical and nonspherical particles. On the whole, maximum errors to be associated to the model estimation of the aerosol extinction coefficient and surface area are of the order of 50%. Conversely, errors associated to volume estimates range from 15% to 100%. To validate the model, a first comparison is performed between lidar and Sun-photometer-derived aerosol optical thickness of both maritime aerosols and Saharan dust.