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Abstract. Sea salt aerosols play an important role in the radiationbudget and atmospheric composition over the Arctic, where the climate israpidly changing. Previous observational studies have shown that Arctic sea ice leads are an important source of sea salt aerosols, and modeling efforts have also proposed blowing snow sublimation as a source. In this study,size-resolved atmospheric particle number concentrations and chemicalcomposition were measured at the Arctic coastal tundra site ofUtqiaġvik, Alaska, during spring (3 April–7 May 2016). Blowing snow conditions were observed during 25 % of the 5-week study period andwere overpredicted by a commonly used blowing snow parameterization based solely on wind speed and temperature. Throughout the study, open leads werepresent locally. During periods when blowing snow was observed, significantincreases in the number concentrations of 0.01–0.06 µm particles(factor of 6, on average) and 0.06–0.3 µm particles (67 %, on average) and a significant decrease (82 %, on average) in 1–4 µmparticles were observed compared to low wind speed periods. These size distribution changes were likely caused by the generation of ultrafineparticles from leads and/or blowing snow, with scavenging of supermicronparticles by blowing snow. At elevated wind speeds, both submicron andsupermicron sodium and chloride mass concentrations were enhanced,consistent with wind-dependent local sea salt aerosol production. Atmoderate wind speeds below the threshold for blowing snow as well as during observed blowing snow, individual sea spray aerosol particles were measured.These individual salt particles were enriched in calcium relative to sodiumin seawater due to the binding of this divalent cation with organic matter in the sea surface microlayer and subsequent enrichment during seawaterbubble bursting. The chemical composition of the surface snowpack alsoshowed contributions from sea spray aerosol deposition. Overall, theseresults show the contribution of sea spray aerosol production from leads onboth aerosols and the surface snowpack. Therefore, if blowing snowsublimation contributed to the observed sea salt aerosol, the snow beingsublimated would have been impacted by sea spray aerosol deposition rather than upward brine migration through the snowpack. Sea spray aerosol production from leads is expected to increase, with thinning and fracturingof sea ice in the rapidly warming Arctic.
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This content will become publicly available on November 1, 2026
Overview of the Chemistry in the Arctic: Clouds, Halogens, and Aerosols (CHACHA) Field Campaign
Abstract The Chemistry in the Arctic: Clouds, Halogens, and Aerosols (CHACHA) field project aimed to advance the understanding of coupled meteorological and chemical processes in the atmospheric boundary layer during the seasonal increase in sea ice fracturing in spring. CHACHA sought to understand the interactions between this changing snow-covered surface, surface-coupled clouds, sea spray aerosols, multiphase halogen chemistry, and impacts of emissions from oil and gas extraction on atmospheric chemistry. The project measured greenhouse gases, reactive gases, size-resolved aerosol number concentrations, cloud microphysical properties, and meteorological conditions in real time, while also collecting particles for offline analysis. Two instrumented aircraft were deployed: the Purdue University Airborne Laboratory for Atmospheric Research and the University of Wyoming King Air. Flights were conducted out of Utqiaġvik, Alaska, between 21 February and 16 April 2022, sampling air over snow-covered and newly frozen sea ice in the Beaufort and Chukchi Seas, over open leads, and over the snow-covered tundra of the North Slope of Alaska, including the oil and gas extraction region near Prudhoe Bay. Observations showed that reactive bromine gases generally peaked near the snow-covered surface and decayed rapidly within the lowest few hundred meters where ozone was depleted, with concentrations reduced by nitrogen oxides emitted from oil fields. Cloud microphysical measurements revealed that thin clouds over and downwind of leads grew in vertical extent after contact with open water. Results from dropsondes indicated that convective boundary layers developed over leads, with depths ranging from 250 to 850 m depending on the fetch.
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- Award ID(s):
- 2000404
- PAR ID:
- 10650584
- Publisher / Repository:
- American Meteorological Society
- Date Published:
- Journal Name:
- Bulletin of the American Meteorological Society
- Volume:
- 106
- Issue:
- 11
- ISSN:
- 0003-0007
- Page Range / eLocation ID:
- E2276 to E2299
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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