A. M. Tafuro

Imaginary refractive-index effects on desert-aerosol extinction versus backscatter relationships at 351 nm: numerical computations and comparison with Raman lidar measurements

A numerical model is used to investigate the dependence at 351 nm of desert-aerosol extinction and backscatter coefficients on particle imaginary refractive index (mi). Three ranges (-0.005 < or = mi < or = -0.001, -0.01 < or = mi < or = -0.001, and -0.02 < or = mi < or = -0.001) are considered, showing that backscatter coefficients are reduced as /mi/ increases, whereas extinction coefficients are weakly dependent on mi. Numerical results are compared with extinction and backscatter coefficients retrieved by elastic Raman lidar measurements performed during Saharan dust storms over the Mediterranean Sea. The comparison indicates that a range of -0.01 to -0.001 can be representative of Saharan dust aerosols and that the nonsphericity of mineral particles must be considered.

In Situ Samplings and Remote Sensing Measurements to Characterize Aerosol Properties over Southeast Italy

Abstract Ground-based particulate matter (PM) samplers, an XeF Raman lidar operating in the framework of the European Aerosol Research Lidar Network (EARLINET), and a sun/sky radiometer operating in the framework of the Aerosol Robotic Network (AERONET) have been used to characterize vertical profiles, optical and microphysical properties, and chemical composition of aerosols during the 29 June–1 July 2005 dust outbreak that occurred over the central-eastern Mediterranean. Aerosol backscatter coefficient, total depolarization, and lidar ratio vertical profiles revealed that a well-mixed dust layer extending from ∼0.5 to 6 km was present over southeastern Italy on 30 June. Sun/sky radiometer measurements revealed a bimodal lognormal size distribution during all measurement days. The particle volume distribution was found to be well correlated either to the PM mass distribution measured at ground by a seven-stage cascade impactor and to the fine to total suspended PM mass ratio measured by ground-based PM s...

Remote Sensing of Aerosols by Sunphotometer and Lidar Techniques

Active and passive remote sensing devices such as lidars and sunphotometers, respectively, are peculiar tools to follow the spatial and temporal evolution of aerosol loads and get complementary data to properly characterize aerosol optical and microphysical properties. A XeF-based Raman lidar is routinely used at the physics department of Lecce’s University (40° 20′ N, 18° 6′ E), to monitor aerosol vertical distributions and characterize aerosol optical properties by the vertical profiles of the backscatter and extinction coefficient, lidar ratio, and depolarization ratio. In addition, a sun/sky radiometer operating within AERONET is used to supplement lidar measurements and better infer aerosol types and properties by columnar values of the particle size distribution, the real and imaginary refractive index, the single scattering albedo and the Angstrom exponent (A). The main objective of this paper is to provide some results on the spatial and temporal evolution of the aerosol properties over south-east Italy, in the central-east Mediterranean basin, by using lidar and sunphotometer measurements. Specifi cally, results on the characterization of the aerosol load from July 18 to July 21, 2005 are reported and particular attention is devoted to the Sahara dust outbreak that has occurred over south-east Italy on July 18 and 19, 2005.