cc-by-4.0Gordon, HamishKirkby, JasperBaltensperger, UrsBianchi, FedericoBreitenlechner, MartinCurtius, JoachimDias, AntonioDommen, JosefDonahue, Neil M.Dunne, Eimear M.Duplissy, JonathanEhrhart, SebastianFlagan, Richard C.Frege, CarlaFuchs, ClaudiaHansel, ArminHoyle, Christopher R.Kulmala, MarkkuKuerten, AndreasLehtipalo, KatrianneMakhmutov, VladimirMolteni, UgoRissanen, Matti P.Stozkhov, YuriTrostl, JasminTsagkogeorgas, GeorgiosWagner, RobertWilliamson, ChristinaWimmer, DanielaWinkler, Paul M.Yan, ChaoCarslaw, Kenneth. S2025-03-242017-06-302017-06-30https://hydatakatalogi-test-24.it.helsinki.fi/handle/123456789/9989Data presented in the manuscript "Causes and importance of new particle formation in the present-day and pre-industrial atmospheres" currently in review. Particle number concentrations (files with initial word "CCN" or "N3") have units of particles per cubic centimetre, calculated at ambient temperature and pressure. Files with initial word "solar" have units of percent. Ion production rates have units ion pairs per cubic centimetre per second. The simulation data presented here was generated with the GLOMAP aerosol model, https://www.see.leeds.ac.uk/research/icas/research-themes/atmospheric-chemistry-and-aerosols/groups/aerosols-and-climate/the-glomap-model/ running on a T42 grid. The manuscript associated with this data was written using results from the CLOUD experiment at CERN, and the author list is a subset of the CLOUD collaboration.Opendataset