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

Abstract

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 andlocal PNC transport to PNC concentrations recorded at the marine backgroundsite. The PSCF results showed that the marine boundary layer was not seriouslyaffected by long-range transport, but that local transport of air pollutionwas recognized as an important factor. North Atlantic and Sea-Marine typeclusters respectively represented 32.1% and 17.9% of the total PNC spectraand 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 whilethe 16-h scale was a constant feature of aerosol PNC evolution in spring, the longer (∼60-h) scalesappeared mainly over the whole year (except June). Principal componentanalysis (PCA) revealed a strong correlation between PNC and NaCl,highlighting the influence of sea-salt aerosols. In addition, PCA also showedthat PNC depended on optical and meteorological parameters such as UVR andtemperature.

Keywords

• Baltic Sea
• 3D CEMBS model
• ecosystem model
• chlorophyll a
• phytoplankton
• nutrients
• zooplankton
• oxygen