Atmospheric aerosols in suburb of Prague: The dynamics of particle size distributions

The paper summarizes the results of a 2-year-long continuous sampling by SMPS and APS spectrometers at the suburban background site in Prague, Suchdol. The campaign was aimed to study the particle number size distributions and their dynamic behavior. It was found that the average total particle number concentration was 7.3 × 103 particles/cm3. The size distributions were often bimodal. The peaks occurring in the accumulation (> 100 nm) and Aitken size range (25–100 nm) were sometimes overlapping each other. When new particles were formed, the peak in the nucleation size range (< 25 nm) dominated. The situations, when the number concentrations of particles smaller than 25 nm in diameter were elevated, mostly indicated the formation of new particles belonging to the category “Banana event.” The kinetic parameters of these nucleation events were estimated; the average value of the formation rate was found to be J10 = 2.6 cm−3 s−1 and the growth rate GR10 = 5.4 nm h− 1. The paper also compares features of all the different situations and events observed, including typical clean days, days dominated by traffic related aerosols (during rush hours) or days characterized by local pollution events. On clean days, the average background particle number concentration was 4 × 103 particles/cm3. On days with anthropogenic pollution, higher than average particle number concentrations were recorded throughout the whole size range with the total average concentration 20 × 103 particles/cm3.

Research Highlights
► Continuous measurement by SMPS and APS spectrometers in Prague.
► Particle number size distributions and dynamic behavior.
► Particle number concentration and meteorology.
► Clean days, rush hour days, local pollution event days.
► Occurrence of new particle formation event days 20.1%.