Evidence for marine biogenic influence on summertime Arctic aerosol

• Published in: Geophysical Research Letters
• Main Authors: Willis, M., Köllner, F., Burkart, J., Bozem, H., Thomas, J., Schneider, J., Aliabadi, A., Hoor, P., Schulz, H., Herber, A., Leaitch, W., Abbatt, J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Arctic
• Online Access: http://hdl.handle.net/11858/00-001M-0000-002D-D378-A

We present vertically resolved observations of aerosol composition during pristine summertime Arctic background conditions. The methansulfonic acid (MSA)-to-sulfate ratio peaked near the surface (mean 0.10), indicating a contribution from ocean-derived biogenic sulfur. Similarly, the organic aerosol (OA)-to-sulfate ratio increased toward the surface (mean 2.0). Both MSA-to-sulfate and OA-to-sulfate ratios were significantly correlated with FLEXPART-WRF-predicted air mass residence time over open water, indicating marine-influenced OA. External mixing of sea salt aerosol from a larger number fraction of organic, sulfate, and amine-containing particles, together with low wind speeds (median 4.7 m s−1), suggests a role for secondary organic aerosol formation. Cloud condensation nuclei concentrations were nearly constant (∼120 cm−3) when the OA fraction was <60% and increased to 350 cm−3 when the organic fraction was larger and residence times over open water were longer. Our observations illustrate the importance of marine-influenced OA under Arctic background conditions, which are likely to change as the Arctic transitions to larger areas of open water.