Integration of backscattering-LIDAR and ground-based meteorological and pollution data in Florence (Italy)

A statistically-significant data set of backscattering LIDAR and ground-based information has been obtained for the planetary boundary layer (PBL) of Florence (I). The summer LIDAR backscattering data at 532 and 1064 nm have been used to estimate both the size and the number concentration of the urban aerosols in the accumulation mode. This technique seems to be relatively insensitive to the aerosol composition. The time-height evolution of the PBL (mainly the stable (SL) and the mixed (ML) layers) has been plotted, together with the meteorological and ground-based pollution data for the 200 measurement days. The ground-based hourly pollution data (NOx, CO) have been compared with the hourly-averaged 1064 nm backscattering at 25 meters above the ground. A correlation, R = 0.65, was obtained between NOx and 1064 nm backscattering during the summer period when the traffic aerosols do not grow considerably after their production. The correlation is not significant during winter, when the growth of the particles is much faster. During winter, the RH variations are more important than aerosol number variations to determine the backscattering evolution.