Consequences of dynamic and timing properties of new aerosol particle formation and consecutive growth events

Abstract

<p><strong>Abstract.</strong> Dynamic properties, i.e. particle formation rate <i>J</i><sub>6</sub> and particle diameter growth rate GR<sub>10</sub>, and timing properties, i.e. starting time (<i>t</i><sub>1</sub>) and duration time interval (Δ<i>t</i>) of 247 quantifiable (class 1A) atmospheric new particle formation (NPF) and consecutive particle diameter growth events identified in the city centre and near-city background of Budapest over 6 full measurement years together with related gas-phase H<sub>2</sub>SO<sub>4</sub> 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 cm<sup>3</sup> of air in 1 s, and cause the particles with a diameter of 10 nm to grow with a typical rate of 7.3 nm h<sup>−1</sup>. Nucleation starts approximately 1 h earlier in the near-city background, it shows substantially smaller <i>J</i><sub>6</sub> (with a median of 2.0 cm<sup>−3</sup> s<sup>−1</sup>) and GR<sub>10</sub> values (with a median of 5.0 nm h<sup>−1</sup>), while the duration of nucleation is similar to that in the centre. Monthly distributions of the dynamic properties and daily maximum H<sub>2</sub>SO<sub>4</sub> 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. Condensing atmospheric chemical species and/or their processes in the city centre seem to contribute equally to new particle formation and particle growth. In the near-city background, however, chemical compounds available and their processes power particle growth more than particle formation. There is a minimum growth rate of approximately 1.8 nm h<sup>−1</sup> that is required for nucleated particles to reach the lower end of the diameter interval measured (6 nm) under the actual/local conditions. Monthly distributions and relationships among the properties mentioned provided several indirect evidence that chemical species other than H<sub>2</sub>SO<sub>4</sub> largely influence the particle growth and possibly atmospheric NPF process as well. The <i>J</i><sub>6</sub>, GR<sub>10</sub> and Δ<i>t</i> can be described by log-normal distribution. Most of the extreme dynamic properties could not be explained by H<sub>2</sub>SO<sub>4</sub> proxy, CS, meteorological data or pollutant gas concentrations. Approximately 40 % of the NPF and growth events exhibited broad beginning, which can be an urban feature. For 9 % of all cases, it was feasible to calculate 2 separate sets of dynamic properties. The later onset frequently shows more intensive particle formation and growth than the first onset by a typical factor of approximately 1.4. The first event is of regional type, while the second event, superimposed on the first, is often associated with sub-regional, thus urban NPF and growth process.</p>

Sources of Total Particles and Cloud Condensation Nuclei Levels in the Eastern Mediterranean: Urban vs Remote Background Environments

“…From the binned particle number concentrations for Nucleation, Aitken and Accumulation mode it occurs that at Finokalia, Aitken and accumulation mode particles were of 386 ± 305 & 1,506 ± 1,107cm -3 while at Thissio the concentrations are remarkably higher, and the respective values were of 1,435 ± 412 & 5,517 ± 1,893cm -3 . The total average particle number concentrations (N total ) were calculated to be as 8,652 ± 8,137cm -3 & 2,958 ± 3,579cm -3 at Thissio and Finokalia, respectively which are well in the range of the respective values reported by Salma et al [6] in the city center of Budapest and in a near-city background. Furthermore, on average, N total at Thissio during winter were higher compared to summer by 53%, while at Finokalia were higher by 24%.…”