Unified database of ozonesounding profiles

The unified database of ozonesounding profiles was obtained through the merging of three existing ozonesounding datasets, provided by the Southern Hemisphere Additional OZonesondes (SHADOZ), the Network for the Detection of Atmospheric Composition Change (NDACC), and the World Ozone and Ultraviolet Radiation Data Centre (WOUDC). Only a few variables of interest were considered to build the unified dataset due to the different formats and amounts of data and metadata provided by each network, despite data often referring to the measurements provided to different initiatives. Furthermore, an algorithm was implemented able to merge the different datasets by handling their different features and duplicated profiles. The selection criteria are summarized below: In case of a single profile for a day (no duplicates), this profile will be saved in the database; In case of duplicates, the profile selection is driven by the dataset maturity and by the availability of measurement uncertainties on the ozone concentration profiles. The uncertainties are provided mainly in the SHADOZ database and for some locations also in the NDACC database. WOUDC, on the other hand, does not provide any uncertainty estimates; Discarded profiles are eventually used to densify the vertical sampling if they provide measurements at different pressure levels not available in the selected profiles.