The importance of blowing snow to halogen-containing aerosol in coastal Antarctica: influence of source region versus wind speed

Abstract

A fundamental understanding of the processes that control Antarctic aerosols is necessary in determining the aerosol impacts on climate-relevant processes from Antarctic ice cores to clouds. The first in situ observational online composition measurements by an aerosol mass spectrometer (AMS) of Antarctic aerosols were only recently performed during the Two-Season Ozone Depletion and Interaction with Aerosols Campaign (2ODIAC). 2ODIAC was deployed to sea ice on the Ross Sea near McMurdo Station over two field seasons: austral spring-summer 2014 and winter-spring 2015. The results presented here focus on the overall trends in aerosol composition primarily as functions of air masses and local meteorological conditions. The results suggest that the impact of long-range air mass back trajectories on either the absolute or relative concentrations of the aerosol constituents measured by (and inferred from) an AMS at a coastal location is small relative to the impact of local meteorology. However, when the data are parsed by wind speed, two observations become clear. First, a critical wind speed is required to loft snow from the surface, which, in turn, increases particle counts in all measured size bins. Second, elevated wind speeds showed increased aerosol chloride and sodium. Further inspection of the AMS data shows that the increased chloride concentrations have more of a "fast-vaporizing" nature than chloride measured at low wind speed. Also presented are the Cl : Na ratios of snow samples and aerosol filter samples, as measured by ion chromatogra-phy, as well as non-chloride aerosol constituents measured by the AMS. Additionally, submicron aerosol iodine and bromine concentrations as functions of wind speed are also presented. The results presented here suggest that aerosol composition in coastal Antarctica is a strong function of wind speed and that the mechanisms determining aerosol composition are likely linked to blowing snow.

On the annual variability of Antarctic aerosol size distributions at Halley Research Station

“…Udisti et al, 2012). The results presented here suggest that, in coastal Antarctica, aerosol composition is a strong function of wind speed and that the mechanisms determining aerosol composition are likely linked to blowing snow (Giordano et al, 2018;Yang et al, 2019;Frey et al, 2020). We note that Legrand et al (2016) suggested that on average, the sea ice and open-ocean emissions equally contribute to the sea salt aerosol load of the inland Antarctic atmosphere.…”

“…Sea spray is almost always reported as the main source of super-micrometre (> 1 µm) aerosols in marine areas, including the Southern Ocean and Antarctica (Quinn et al, 2015;Bertram et al, 2018). However, models of global sea salt distribution have frequently underestimated concentrations at polar locations (Gong et al, 2002). Rankin and Wolff (2003) suggested the Antarctic sea ice zone was a more important source of sea salt aerosol, during the winter months, than the open ocean.…”

“…It is interesting to note that the recent, spatially extensive study of the concentration of sea salt aerosol throughout most of the depth of the troposphere and over a wide range of latitudes (Murphy et al, 2019) reported a source of sea salt aerosol over pack ice that is distinct from that over open water, likely produced by blowing snow over sea ice (Huang et al, 2018;Giordano et al, 2018;Frey et al, 2020). In recent years, a number of long-term aerosol size distribution datasets have been discussed (Järvinen et al, 2013;, but these types of datasets are still scarce.…”

Simultaneous Detection of Alkylamines in the Surface Ocean and Atmosphere of the Antarctic Sympagic Environment

“…Atmospheric ambient sampling. In the clean, marine Antarctic atmosphere, the particle number concentration of primary and secondary aerosols is mainly driven by the seasonality of biological productivity in the Southern Ocean [16][17][56][57][58][59] . The mechanisms, however, for the production of either primary or secondary biogenic aerosols are not fully clarified.…”

Evaluating the impact of blowing snow sea salt aerosol on springtime BrO and O<sub>3</sub> in the Arctic

“…Peterson et al (2017) and Simpson et al 85 (2017) reported aircraft observations of the vertical distribution of BrO and aerosol extinction consistent with initial activation on snowpack followed by transport aloft (500-1000 m), where high BrO was sustained by recycling on aerosols. More recently, Frey et al (2019) and Giordano et al (2018) reported direct observations of SSA production from blowing snow above sea ice. In particular, Frey et al (2019) found that the Br − /Na + ratio of blowing snow SSA observed at 29 m above the ground decreased by a factor of 2-3 relative to observations at 2 m, suggesting rapid Br − release via (R1) from blowing snow SSA.…”