Abstract. Dynamic properties, i.e.
particle formation rate J6 and particle diameter growth rate GR10,
and timing properties, i.e. starting time (t1) and duration time
interval (Δt) of 247 quantifiable atmospheric new aerosol particle formation (NPF) and growth events
identified in the city centre and near-city background of Budapest over 6
full measurement years, together with related gas-phase H2SO4
proxy, condensation sink (CS) of vapours, basic meteorological data and
concentrations of criteria pollutant gases were derived, evaluated, discussed
and interpreted. In the city centre, nucleation ordinarily starts at
09:15 UTC + 1, and it is maintained for approximately 3 h. The NPF and
growth events produce 4.6 aerosol particles with a diameter of 6 nm in
1 cm3 of air in 1 s and cause the particles with a diameter of 10 nm
to grow at a typical rate of 7.3 nm h−1. Nucleation starts
approximately 1 h earlier in the near-city background, and it shows
substantially smaller J6 (with a median of 2.0 cm−3 s−1) and
GR10 values (with a median of 5.0 nm h−1), while the duration of
nucleation is similar to that in the centre. Monthly distributions of the
dynamic properties and daily maximum H2SO4 proxy do not follow
the mean monthly pattern of the event occurrence frequency. The factors that
control the event occurrence and that govern the intensity of particle
formation and growth are not directly linked. New particle formation and
growth processes advance in a different manner in the city and its close
environment. This could likely be related to diversities in atmospheric
composition, chemistry and physics. Monthly distributions and relationships
among the properties mentioned provided indirect evidence that chemical
species other than H2SO4 largely influence the particle growth
and possibly atmospheric NPF process as well. The J6, GR10 and
Δt can be described by a log-normal distribution function. Most extreme
dynamic properties could not be explained by available single or compound
variables. Approximately 40 % of the NPF and growth events exhibited
broad beginning, which can be an urban feature. For doublets, the later onset
frequently shows more intensive particle formation and growth than the first
onset by a typical factor of approximately 1.5. The first event is attributed
to a regional type, while the second event, superimposed on the first, is often
associated with subregional, thus urban NPF and growth processes.
Observations of ultrafine aerosol particle formation and growth in boreal forest