Trends, composition, and sources of carbonaceous aerosol in the last 18 years at the Birkenes Observatory, Northern Europe

Abstract. We present 18 years (2001–2018) of aerosol measurements: organic- and elemental carbon (OC and EC), organic tracers (levoglucosan, arabitol, mannitol, trehalose, glucose, 2-methyltetrols), trace elements and ions – at the Birkenes Observatory (Southern Norway), a site representative of the Northern European region. The OC / EC (2001–2018) and the levoglucosan (2008–2018) time series are the longest in Europe, with OC / EC available for the PM10, PM2.5 (fine) and PM10-2.5 (coarse) size fractions, providing the opportunity for a nearly two-decade long assessment. Using positive matrix factorisation (PMF) we identify six carbonaceous aerosol sources at Birkenes: Mineral dust dominated (MIN), traffic/industry-like (TRA/IND), short range transported biogenic secondary organic aerosol (BSOASRT), primary biological aerosol particles (PBAP), biomass burning (BB), and ammonium nitrate dominated (NH4NO3), and one low carbon fraction, sea salt (SS). We observed significant (p