Characterization of new particle formation events at a background site in Southern Sweden: relation to air mass history

Abstract

A B S T R A C T Particle formation events were analysed from aerosol number size distribution data collected at a background station in southern Sweden between February 2001 and May 2004. Events occurred on about 36% of all days and were favoured by high global radiation values. The clearest events (class I, 20% of all days) were observed when the formation rate of activated hypothetical clusters around 1 nm diameter, J 1 was higher than 10 (180 * CondS-0.60) , where CondS is the condensation sink (in s −1 ). The median condensable vapour concentration, observed formation rate at 3 nm, and growth rate during class I events were 3.0 × 10 7 cm −3 , 1.1 cm −3 s −1 and 2.1 nm h −1 , respectively. On 7% of all days, it was possible to observe growth of the newly formed particles exceeding 30 nm geometric mean diameter during event days in the evening, which is important for the regional particle population, and thereby the climate. A trajectory analysis revealed that cleaner air masses were relatively more important for the contribution of Aitken mode particles than polluted ones. Class I events were registered on 36% of all days when trajectories had passed over the open sea, indicating that ship traffic can contribute to particle formation and growth.

Secondary new particle formation in Northern Finland Pallas site between the years 2000 and 2010

“…The major findings of this 10-year NPF analysis confirm the results of previous studies made in Pallas and in other Nordic stations Kristensson et al, 2008;Vehkamäki et al, 2004). The formation and growth rates analysed for two years in Pallas by Komppula et al (2003) and the potential of NPF to increase CCN 80 seem to hold for longer time periods.…”

“…The observed seasonal NPF pattern with a spring maximum and winter minimum is typical for all Nordic stations Kristensson et al, 2008;Vehkamäki et al, 2004). However, in southern Nordic stations (Hyytiälä in Finland, Aspvreten and Vavihill in Sweden) an additional summer minimum around July is observed, and can be at least partly explained by the increasing fraction of undefined arting time of the NPF events, extrapolated backwards to 2 nm for class I events (red circles), and observations times both for class s II events (red and blue crosses).…”

“…Field studies made in Northern Europe have revealed that NPF events usually take place on 20-60 % of all days (Dal Maso et al, 2005;Dal Maso et al, 2007;Kristensson et al, 2008;Vehkamäki et al, 2004). Similar NPF frequencies have been observed in most other European sites , as well as in Australian eucalyptus forest (Suni et al, 2008) and in Indian Himalayas .…”

Impacts of new particle formation on aerosol cloud condensation nuclei (CCN) activity in Shanghai: case study

“…Many studies have observed greater NPF frequency during the spring in the Northern Hemisphere. For example, a seasonal NPF pattern with a spring maximum and winter minimum is typical for all Nordic stations Kristensson et al, 2008;Vehkamäki et al, 2004). In the North China Plain, the number of events was higher in the spring months .…”

Maternal exposure to air pollution and type 1 diabetes – Accounting for genetic factors

“…Emissions from eastern Denmark have also been added into the EDB, since emissions from eastern Denmark are quite high and westerly winds are dominant (Kristensson et al 2008).…”