Copernicus is the Earth observation component of the European Union’s space programme. The European Centre for Medium-Range Weather Forecasts (ECMWF) has been appointed by the European Commission with funding from the EU to operate the Copernicus Atmosphere Monitoring Service and the Copernicus Climate Change Service on its behalf. Institute of Methodologies for Environmental Analysis (IMAA) of the National Research Council (CNR) has been contracted by ECMWF to implement the C3S2 311 Lot2 “Comprehensive Upper-Air, Baseline and Reference in situ observations”, which valorises the effort spent in Cop1 within the C3S 311a Lot3 (“Access to observations from baseline and reference networks”) and C3S 311c Lot2 (“Historic In Situ Upper Air Database”) contracts.