| In spite of fact that the first report on the new particle formation (NPF) itself was
done by John Aitken more than one century ago (Aitken, 1898), a phenomenon
of NPF bursts taken place in the atmosphere was discovered not very long ago.
Nevertheless, to date it is known that they may occur quite often in a variety of
environments (Kulmala et al., 2004; Hirsikko et al., 2011). Siberia occupies a vast area
covered by forests, but the comprehensive data on burst frequency, as well as on
formation and growth rates of freshly nucleated particles in this key region are
still lacking. Continuous measurements of aerosol size distribution carried out in
recent years at two West Siberian stations (TOR-station – 56o28’41"N, 85o03’15"E;
Fonovaya Observatory – 56o25’07"N, 84o04’27"E) allowed this gap in data to be filled
up.
Analysis of the size spectra classified in accordance with criteria proposed by Dal Maso et
al. (2005) and Hammed et al. (2007) enabled a conclusion to be drawn that NPF events in
Wets Siberia are more often observed during spring (from March to May) and early autumn
(secondary frequency peak in September). On average, particle formation bursts took place
on 23-28Â% of all days. Such a seasonal pattern of the NPF occurrence is very similar
to one observed at SMEAR II Station (Hyytiälä, Finland; DalÂMaso et al. 2005,
2007).
Formation rates (FR) of particles with diameters below 25 nm varied in a wide range from
0.1 to 10 cm-3 s-1. Mean values of FR for the entire period of observations were 1.7
cm-3s-1 (median = 1.13 cm-3 s-1) at TOR-station and 0.88 cm-3 s-1 (median = 0.69
cm-3 s-1) at Fonovaya Observatory. Enhanced values of FR are usually observed from
spring to autumn. Mean growth rates of observed at TOR-station and Fonovaya Observatory
were 6.5 nm h-1 (median = 5.0 nm h-1) and 8.3 nm h-1 (median = 6.4 nm h-1),
respectively.
This work was supported by the Branch of Geology, Geophysics and Mining Sciences of
RAS (ProgramÂNo. 5); State contracts of the Ministry of Education and Science
of Russia No. 14.604.21.0100, (RFMTFIBBB210290) and No. 14.613.21.0013
(RFMEFI61314X0013); and Russian Foundation for Basic Research (grant No.
14-05-00590).
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aerosol size distribution data from SMEAR II, Hyytiälä, Finland, Boreal Environ. Res. 10,
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