Development of a versatile ground-based UV lidar prototype, featuring a CO2 Raman channel, in support of the ASI-NASA CALIGOLA mission

This thesis investigates the development and application of Raman lidar systems for measuring atmospheric compositional and thermodynamic properties. The research focuses on two ground-based lidar prototypes, CONCERNING and MARCO, developed during the PhD program. These systems, utilizing both rotational and vibrational Raman lidar techniques in the UV spectrum, incorporate advanced technologies for laser emission, spectral selection, optical signal detection, and data acquisition. Housed in rugged, weather-resistant containers with remote control capabilities, these lidars offer continuous and unattended measurement capabilities. MARCO, notably, is the first lidar prototype that demonstrates the feasibility of a Raman lidar based on a micro-pulse laser source. The two lidar systems were deployed in various national and international measurement campaigns, such as WaLiNeAs, BELLA, and DECIPHER, highlighting their capabilities in studying extreme precipitation events, characterizing the atmospheric boundary layer, and investigating transport and mixing phenomena in mountain areas. Future campaigns are planned to further explore marine aerosol and cloud interaction. As part of the research project, a Raman lidar simulator was developed to define the characteristics of the spectral selection devices required for CO2 mixing ratio measurements, evaluate system performance, and calibrate the measurements through an original technique, taking advantage of day-time lidar background signal. The CO2 measurement capability was successfully implemented in the CONCERNING lidar, with promising results demonstrated through calibrated measurements compared to satellite data. The thesis contributes significantly to the CALIGOLA (Cloud Aerosol LIdar for Global scale observations of the Ocean-Land-Atmosphere system) satellite mission, a collaborative project between the Italian Space Agency and NASA, with the University of Basilicata representing the focal point for the scientific activities. The research provided valuable insights into the Raman lidar technique and served as a testing platform for state-of-the-art technological solutions and techniques that will be implemented in the CALIGOLA mission. The developed lidar simulator will be enhanced to form the foundation of a comprehensive end-to-end lidar simulator of the space-borne lidar. Additionally, the two lidar systems' measurement capabilities will be instrumental in calibrating and validating CALIGOLA's atmospheric products and will support future synergetic studies, enhancing the understanding of feedback and coupling mechanisms within Earth's biogeochemical cycles.