18 Aug 2022
18 Aug 2022
Status: this preprint is currently under review for the journal ACP.

Characterization of ultrafine particles and the occurrence of new particle formation events in an urban and coastal site of the Mediterranean area

Adelaide Dinoi1, Daniel Gullì2, Kay Weinhold3, Ivano Ammoscato2, Claudia Roberta Calidonna2, Alfred Wiedensohler3, and Daniele Contini1 Adelaide Dinoi et al.
  • 1Institute of Atmospheric Sciences and Climate, ISAC-CNR, S. P. Lecce-Monteroni km 1.2, 73100 Lecce, Italy
  • 2Institute of Atmospheric Sciences and Climate, ISAC-CNR, Zona Industriale, I-88046 Lamezia Terme (CZ), Italy
  • 3Leibniz Institute for Tropospheric Research, 04318, Leipzig, Germany

Abstract. In this work, new particle formation events (NPF) occurred at two locations in Southern Italy, the urban background site of Lecce (ECO station) and the coastal site of Lamezia Terme (LMT station), are identified and analysed. The study aims to compare the properties of NPF events at the two sites located 225 km away from each other and characterized by marked differences in terms of emission sources and local weather dynamics. Continuous measurements of particle number size distributions, in the size range from 10 nm to 800 nm, were performed at both sites by a Mobility Particle Size Spectrometer (MPSS). The occurrence of NPF events, observed throughout the study period lasted five years, produced different results in terms of frequency of occurrence, 25 % of the days at ECO and 9 % at LMT. NPF events showed seasonal patterns, higher frequency during spring and summer at the urban background site, while at the coastal site during the autumn-winter period. Some of these events happened simultaneously at both sites, indicating the occurrence of the nucleation process on a large spatial scale (regional event). Cluster analysis of 72 h back-trajectories showed that during the NPF events the two stations were influenced by similar air masses, most of which originating from the North-Western directions. Local meteorological conditions characterized by high pressure, with a prevalence of clear skies, low level of relative humidity (RH < 52 %), and moderate winds (3–4 m s-1) dominated the NPF events at both sites. Notable differences were observed in SO2 and PM2.5 concentrations, resulting in ~65 % and ~80 % lower at LMT compared to ECO, respectively. It is likely that the lower level of SO2, recognized as one of the main gas precursors involved in the nucleation process, can be responsible for the smaller NPF frequency of occurrence (~60 % less than ECO) observed in LMT.

Adelaide Dinoi et al.

Status: open (until 29 Sep 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-512', Anonymous Referee #1, 27 Sep 2022 reply

Adelaide Dinoi et al.

Adelaide Dinoi et al.


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Short summary
In this study, particle number size distribution analysis was performed with the purpose of characterizing new particle formation (NPF) events occurred in two areas of southern Italy during 5 years of measurements. The identification of NPF events produced different results in terms of frequency and seasonality. Some of the main variables involved in the process, the local atmospheric conditions in which the events occurred and the role of the air masses were discussed and compared.