Atmospheric Aerosol Properties from Ceilometer and Photometer Observations at the L'Aquila Site

The ground-based instruments are still a backbone of high-quality atmospheric observation systems, providing high temporal resolution observations and a reference for satellite instruments validation. Some of them are relative cheap if compared to other research systems, and work automatically requiring little maintenance efforts from operators. This is the case of photometers and ceilometer, which are able to measure atmospheric constituents like aerosols, water vapor and clouds. In this work these instruments are used jointly with the aim to retrieve aerosol properties, analyzing the data collected at L’Aquila site. For each system, limitations and type of observable that is possible to derive are shown. Notably, using the specific ceilometer model installed at L’Aquila, the measured backscatter profile is influenced by the water vapor content. The column of water vapor at L’Aquila is investigated and compared against photometer, GNSS and radiosounding, at different time scales, to assess the influence on ceilometer profiles. An important advancement in photometry field is the use of lunar observations to partially cover the nighttime gap. The workflow for lunar photometry is developed and compared with the method applied in AERONET network. Finally, the algorithm GRASP for jointly inverting photometer and ceilometer observations is shown. Despite some inherent limitations and assumption, the photometer and ceilometer synergy is way to retrieve micro-physical and optical properties of atmospheric aerosol, requiring relative low-cost and low-maintenance instruments that can be applied extensively on the globe.