“…Due to its relatively long radioactive half-life (53.22 d) and its cosmogenic origin in the upper troposphere and lower stratosphere (UT-LS) (Lal and Peters, 1967), 7 Be is considered a tracer for intrusion of stratospheric air into the troposphere and large-scale subsidence (e.g., Liu et al, 2016;Chae and Kim, 2019;Heikkila et al, 2008). The variability of the 7 Be activity concentration in surface layers is driven by both static and dynamic factors, e.g., geographical location of the monitoring sites (e.g., Hernández-Ceballos et al, 2015), seasonal atmospheric processes driving transport of carrier aerosols (Lal and Peters, 1967), stratosphere-troposphere air mass exchange (Cristofanelli et al, 2003(Cristofanelli et al, , 2009Putero et al, 2016;Brattich et al, 2017a), synoptic influences (Usoskin E. Be concentration events at the surface in northern Europe et al, 2009), downward transport in the troposphere (Lee et al, 2007), solar activity, and dry and wet deposition (e.g., Hernández-Ceballos et al, 2015, 2016Ioannidou and Papastefanou, 2006).…”