Long-term Trends for Marine Sulfur Aerosol in the Alaskan Arctic and Relationships with Temperature

Abstract:

Marine aerosol can play an important role in cloud-aerosol interactions in the Arctic summer. Increases in temperature and decreases in sea ice extent have the potential to affect marine biogenic aerosol sources. Concentrations in marine sulfur aerosol, such as methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO₄^2-), are likely to change as a result. Long term studies of aerosol composition in the Arctic are vital to understand these changes as well as potential interactions with the Arctic climate. Aerosol samples were collected over three summers at two coastal sites on the North Slope of Alaska: Utqiaġvik and Oliktok Point. Results show concentrations of MSA followed previously reported seasonal trends with marine primary productivity influencing both sites. The data was then combined with a data set collected at Utqiaġvik for a 20-year record (1997-2017). Concentrations of MSA had an increase of +2.5% per year, while concentrations of nss-SO₄^2- had an increase of +2.1% per year over the 2 decades. Analysis of meteorological parameters indicates that ambient temperature may be an influence on MSA concentrations, likely related to other factors including sea surface temperature, sea ice extent, and temperature dependent chemical reactions. Analysis of samples at Oliktok Point suggest that having consistent air mass source regions is necessary to observe this relationship with temperature. Individual particle analysis at Oliktok Point also highlight the connection between marine and oil field emissions in the region. The results of this study show how vital continued study and understanding of MSA and other marine sulfur aerosol in the Arctic is.