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Significant increase of aerosol number concentrations in air masses crossing a densely trafficked sea area

Kecorius S., Kivekäs N., Kristensson A., Tuch T., Covert D. S., Birmili W., Lihavainen H., Hyvärinen A.-P., Martinsson J., Sporre M. K., Swietlicki E., Wiedensohler A., Ulevicius V.

Oceanologia

2016

No. 58 (1)

1--12

In this study, we evaluated 10 months data (September 2009 to June 2010) of atmospheric aerosol particle number size distribution at three atmospheric observation stations along the Baltic Sea coast: Vavihill (upwind, Sweden), Utö (upwind, Finland), and Preila (downwind, Lithuania). Differences in aerosol particle number size distributions between the upwind and downwind stations during situations of connected atmospheric flow, when the air passed each station, were used to assess the contribution of ship emissions to the aerosol number concentration (diameter interval 50–400 nm) in the Lithuanian background coastal environment. A clear increase in particle number concentration could be noticed, by a factor of 1.9 from Utö to Preila (the average total number concentration at Utö was 791 cm−3), and by a factor of 1.6 from Vavihill to Preila (the average total number concentration at Vavihill was 998 cm−3). The simultaneous measurements of absorption Ångström exponents close to unity at Preila supported our conclusion that ship emissions in the Baltic Sea contributed to the increase in particle number concentration at Preila.

Observations of the aerosol particle number concentration in the marine boundary layer over the south-eastern Baltic Sea

Byčenkiene S., Ulevicius V., Prokopčiuk N., Jasinevičiene D.

Oceanologia

2013

No. 55 (3)

573--598

Continuous measurements of the aerosol particle number concentration (PNC) in the size range from 4.5 nm to 2 µm were performed at the Preila marine background site during 2008–2009. The concentration maxima in summer was twice the average (2650±50 cm-3). A trajectory-based approach was applied for source identification. Potential Source Contribution Function (PSCF) analysis was performed to estimate the possible contribution of long-range and local PNC transport to PNC concentrations recorded at the marine background site. The PSCF results showed that the marine boundary layer was not seriously affected by long-range transport, but that local transport of air pollution was recognized as an important factor. North Atlantic and Sea-Marine type clusters respectively represented 32.1% and 17.9% of the total PNC spectra and were characterized by the lowest PNCs (1080±1340 and 1210±1040 cm-3 respectively) among all clusters. Wavelet transformation analysis of 1-h aerosol PNC indicated that while the 16-h scale was a constant feature of aerosol PNC evolution in spring, the longer (∼60-h) scales appeared mainly over the whole year (except June). Principal component analysis (PCA) revealed a strong correlation between PNC and NaCl, highlighting the influence of sea-salt aerosols. In addition, PCA also showed that PNC depended on optical and meteorological parameters such as UVR and temperature.

Observations of new particle formation events in the south-eastern Baltic Sea

Plauškaite K., Ulevicius V., Špirkauskaite N., Byčenkiene S., Zieliński T., Petelski T., Ponczkowska A.

Oceanologia

2010

No. 52 (1)

53-75

New particle formation and growth were observed at a coastal site (Preila station, Lithuania) during 1997 and 2000-2002. The total amount of data analysed covers 291 one-day periods, 45 (15%) of which were long-term, new particle formation days. Short-term nucleation events (from a few minutes to one hour) and long-term events (from one to eight hours) were identified. The mean particle growth rate, condensation sink and condensable vapour source rate during nucleation events were 3.9 nm h*-1, 1.45 × 10*-3 cm*-3 s-1 and 7.5 x 104 cm-3 s-1 respectively. The average formation rate J_10 was 0.4 cm-3 s-1. The nucleation events were accompanied mainly by air masses transported from the north (43%) and north-west (19%). Meteorological parameters and trace gas (O3, SO2, NO2) concentrations were also analysed. It was found that nucleation events are related to high levels of solar radiation.