APP (YOPP) - Antarctic Precipitation Properties from ground-based instruments

The knowledge of properties and quantitative measurement of solid precipitation in Antarctica is of fundamental importance as precipitation represents the main input of Antarctic ice sheet mass, the variations of which have a direct and non-negligible effect on the average level of the oceans at global scale. Characterization and quantification of the precipitation is crucial in defining and validating global climate models and numerical weather prediction models, as well as anchoring and validating space-borne remote sensing estimates from missions like CloudSAT and EarthCARE. A snow and cloud microphysics observatory has been set up at the Italian Antarctic station Mario Zucchelli (MZS), integrating the pre-existing instrumentation for weather measurements. In particular, a 24-GHz vertical pointing Doppler radar, the METEK's Micro Rain Radar 2 (MRR-2), and a laser disdrometer, the OTT Parsivel, have been integrated with the advanced weather stations, radiosoundings and the ceilometer already present at MZS. The synergy between the set of instruments allows for characterizing precipitation and studying properties of Antarctic precipitation such as dimension, shape, fall behavior, particle number density, particles size distribution, particles terminal velocity, reflectivity factor and information on their vertical extent. APP started as a four-year project in July 2017, covering the Special Observation Period (SOP) in the Southern Hemisphere of Year of Polar Predicition (YOPP) period. APP can provide specific measurements for precipitation occurring over the Antarctic coast at high temporal resolution, in particular specific snow products such as snow rate, snow depth and their water equivalent. In November 2023 the observatory received an additional instrument, the Thies Clima 3D Stereo imaging disdrometer, which was previously installed for one year in Italy for testing, at the Casale Calore (AQ) meteorological observation site from the University of L'Aquila. The research team of the first two years was coordinated by Nicoletta Roberto, with operational units at the Rome unit of the CNR-ISAC (Luca Baldini, Elisa Adirosi, Stefano Dietrich) and at the Department of Physics and Astronomy of the University of Bologna (Rolando Rizzi, Federico Porcù, Tiziano Maestri, Alessandro Bracci). From 2020 the coordination of the project passed to Luca Baldini (CNR-ISAC) and the work team was extended with the research fellows Giacomo Roversi and Sabina Angeloni.