Synergetic use of a ground based-Raman lidar and airborne spectrometers to characterize the evolution of a cirrus cloud

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 system was involved in a measurement campaign (5- 10 September 2004) in the frame of EAQUATE, an international experiment for hyper-spectral atmospheric sounding validation. The experiment involved the NASA Proteus aircraft, equipped with the sensors NAST thermal infrared interferometer (NAST-I) and microwave radiometer (NAST-M), the Scanning HIS infrared interferometer (S-HIS), and a range of ground based and airborne remote sensing instruments. On the evening of September 6, 2004, the Proteus aircraft flew four times over a moderately thick high cirrus cloud in the Potenza region. The evolution of the cirrus cloud was monitored by BASIL, providing measurements of particle backscatter and extinction, water vapour mixing ratio, atmospheric temperature and relative humidity. Information from three radiosondes launched from the IMAA ground station was also considered. Radiance measurements by NAST-I have been compared with accurate radiance simulations based on data from BASIL and the radiosondes. Based on the quality of the comparison among simulated and measured radiances, it has been possible to define the vertical structure in terms of fluxes and cooling/heating rates, thus providing a link between the measured state and the time evolution of the cirrus cloud. The effectiveness of the methodology has been also tested and verified on a clear sky case on September 8, 2004.