A preliminary study on the correlation between TOMS aerosol index and ground-based measured aerosol optical depth

The aim of this work is to study the correlation between ground-based measu red aerosol optical depth (AOD) and TOMS Aerosol Index. For this reason, tw o AOD data-sets have been analysed. The first set of measurements has been obtained in a desert plateau in Namibia during July 1998, while the second one has been collected in Tito Scalo (Italy), a very small industrial zone surrounded by a large rural area, in June-July 2000. The AOD has been compu ted in the spectral range 400-870 nm with a resolution of 3 nm by measuring the direct solar irradiance. The used spectroradiometer is an Optical Spec trum Analyser, equipped with a continuously rotating diffraction grating. S uccessively, a correlation between the Earth Probe TOMS Aerosol Index, whos e definition uses backscattered radiances at 331 and 360 nm, and the AOD in the visible range was searched for. A satisfying correlation was found, wh ose Pearson correlation coefficient R-2 values range from 0.64 to 0.91. (C) 2001 Elsevier Science Ltd. All rights reserved.