UV Raman Lidar Mesurements of relative Humidity for the Characterization of Aerosol and Cloud Microphysical Properties

The lidar measurements discussed in this paper were performed in Potenza (40o38’45”N, 15o48’32” - Southern Italy) by the DIFA-Univ. of BASILicata Raman lidar system (BASIL). The major feature of BASIL is its capability to perform high-resolution and accurate measurements of atmospheric temperature, both in daytime and night-time, based on the application of the rotational Raman lidar technique in the UV [1]. Besides temperature, BASIL is capable to provide measurements of particle backscatter at 355 and 532 nm, particle extinction at 355 nm, particle depolarization at 355 and water vapour mixing ratio both in daytime and night-time. Relative humidity measurements are obtained from simultaneous water vapour and temperature measurements. These parameters represents a suitable ensemble of measurements for the study of meteorological processes. Specific case studies are considered and discussed to assess relative humidity lidar measurement capability in presence of aerosols and clouds. Measurements of aerosol backscatter as a function of relative humidity are reported and discussed, highlighting the swelling tendency of hygroscopic aerosol for large relative humidity values.