A full year of aerosol size distribution data from the central Arctic under an extreme positive Arctic Oscillation: Insights from the MOSAiC expedition
- 1Institute for Atmospheric and Earth System Research (INAR)/Physics, Faculty of Science, University of Helsinki, P.O. Box 64, Helsinki, 00014, Finland
- 2Extreme Environments Research Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Sion, 1951, Switzerland
- 3Institute of Marine Science, Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
- 4National Centre for Atmospheric Science, The School of Geography, Earth and Environmental Sciences, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
- 5Institute for Meteorology and Geophysics, University of Vienna
- 6Atmospheric Composition Research, Finnish Meteorological Institute, Helsinki, Finland
- 7Department of Environmental Science, iClimate, Arctic Research Center, Aarhus University, Roskilde, Denmark
- 8Environment and Climate Change Canada, Science and Technology Branch, Toronto, Canada
- 9Department of Applied Environmental Science (ITM), Stockholm University, 11418 Stockholm, Sweden
- 10Climate & Atmosphere Research Centre (CARE-C), The Cyprus Institute, P.O. Box 27456, Nicosia, 1645, Cyprus
- 11The National Research Centre for the Working Environment, Copenhagen, Denmark
Abstract. The Arctic environment is rapidly changing due to accelerated warming in the region. The warming trend is driving a decline in sea ice extent, which thereby enhances feedback loops in the surface energy budget in the Arctic. Arctic aerosols play an important role in the radiative balance, and hence the climate response, in the region; yet direct observations of aerosols over the Arctic Ocean are limited. In this study, we investigate the annual cycle in the aerosol particle number size distribution (PNSD), particle number concentration (PNC), and black carbon (BC) mass concentration in the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. This is the first continuous, year-long dataset of aerosol PNSD ever collected over the sea ice in the central Arctic Ocean. We use a k-means cluster analysis, FLEXPART simulations, and inverse modeling to evaluate seasonal patterns and the influence of different source regions on the Arctic aerosol population. Furthermore, we compare the aerosol observations to land-based sites across the Arctic, using both long-term measurements and observations during the year of the MOSAiC expedition (2019–2020), to investigate interannual variability and to give context to the aerosol characteristics from within the central Arctic. Our analysis identifies that, overall, the central Arctic exhibits typical seasonal patterns of aerosols, including anthropogenic influence from Arctic Haze in winter and secondary aerosol processes in summer. The seasonal pattern corresponds with the global radiation, surface air temperature, and the timing of sea ice melting/freezing, which drives changes in transport patterns and secondary aerosol processes. In winter, the Norilsk region in Russia/Siberia was the dominant source of Arctic Haze signal in the PNSD and BC observations, which contributed to higher accumulation mode PNC and BC mass concentration in the central Arctic than at land-based observatories. We also show that the wintertime Arctic Oscillation (AO) phenomenon, which was reported to achieve a record-breaking positive phase during January–March 2020, explains the unusual timing and magnitude of Arctic Haze across the Arctic region compared to longer-term observations. In summer, the PNC of nucleation and Aitken mode aerosol is enhanced, but concentrations were notably lower in the central Arctic over the ice pack than at land-based sites further south. The analysis presented herein provides a current snapshot of Arctic aerosol processes in an environment that is characterized by rapid changes, which will be crucial for improving climate model predictions, understanding linkages between different environmental processes, and investigating the impacts of climate change in future Arctic aerosol studies.
Matthew Boyer et al.
Matthew Boyer et al.
Matthew Boyer et al.
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