Thirty Years of Arctic Primary Marine Organic Aerosols: Patterns, Seasonal Dynamics, and Trends (1990–2019)

Abstract. Changing Arctic climate patterns have led to sea ice retreat, impacting ocean and atmospheric dynamics as well as marine ecosystems. Reduced sea ice cover likely enhances emissions of primary marine aerosols (sea salt and organic matter) via bubble bursting, potentially amplifying aerosol-cloud interactions. Moreover, primary marine organic aerosol (PMOA) production is closely linked to variations in marine biological productivity. This study examines the emission patterns, seasonality, and historical trends of key biomolecule groups (dissolved carboxylic acid-containing polysaccharides (PCHO), dissolved combined amino acids (DCAA), and polar lipids (PL)) within the Arctic Circle from 1990 to 2019. Surface ocean concentrations of these groups are derived from a biogeochemistry model and used as input to the aerosol-climate model ECHAM-HAM. Results indicate that the strong seasonality in biomolecule concentrations and PMOA emissions is driven by marine productivity and sea salt emissions. These quantities peak from May to September, coinciding with the phytoplankton bloom and seasonal sea ice minimum. Accumulated aerosol emissions and burdens over the Arctic increased by at least 7 % and 4 %, respectively, between the first and second halves of the study period. Summer trend analysis (June–August) reveals a strong reduction in sea ice that correlates with rising concentrations of organic groups in seawater in the inner Arctic. Positive emission anomalies have become more frequent over the past 15 years, indicating an overall upward trend. Average PMOA production has increased by 0.8 % per year since 1990. However, changes vary across biomolecular types and Arctic subregions, with PCHO showing the largest relative increase.