LAUSR

This review focuses on the observed characteristics of atmospheric newparticle formation (NPF) in different environments of the global troposphere. After a short introduction, wewill present a theoretical background that discusses themethods used to analyzemeasurement data on atmospheric NPF and the associated terminology.Wewill update on our current understanding of regionalNPF, i.e. NPF taking simultaneously place over large spatial scales, and complement that with a full review on reportedNPF and growth rates during regionalNPF events.Wewill shortly review atmospheric NPF taking place at sub-regional scales. Since the growth of newly-formed particles into larger sizes is of great current interest, wewill briefly discuss our observation-based understanding onwhich gaseous compounds contribute to the growth of newly-formed particles, andwhat implications this will have on atmospheric cloud condensation nuclei formation.Wewillfinish the reviewwith a summary of ourmain findings and future outlook that outlines the remaining research questions and needs for additionalmeasurements.