Aerosol source identification in the spring and summertime central Arctic Ocean using high-resolution mass spectrometry during MOSAiC

The Arctic region is experiencing considerable changes and is warming at a rate three to four times as fast as the rest of the world. Aerosols, which can be from natural or anthropogenic sources, locally emitted or long-range transported, play a crucial role in the Arctic radiative balance by directly absorbing or scattering incoming solar radiation or indirectly changing cloud properties and modulating cloud formation mechanisms. Here, we investigate the sources and climate-relevant characteristics (e.g. degree of oxygenation and cloud condensation nuclei number concentrations) of anthropogenic and natural aerosols in the central Arctic Ocean, using data collected during the MOSAiC expedition with a high-resolution time-of-flight aerosol mass spectrometer. Using positive matrix factorization on the organic fraction of aerosols during spring and summertime (March – July), we identified six chemical sources of organic aerosols (OA): a hydrocarbon-like factor, a Haze factor, two factors related to two extreme events of warm air mass intrusions in mid-April, an Arctic oxygenated factor and a Marine factor. Together, these results suggest that OA from anthropogenic origin dominate the central Arctic OA budget until at least the month of May, where episodic spikes in naturally-sourced marine OA, originating from the marginal ice-zone start to become important.