Preprints
https://doi.org/10.5194/egusphere-2022-310
https://doi.org/10.5194/egusphere-2022-310
 
11 May 2022
11 May 2022

Modelling wintertime Arctic Haze and sea-spray aerosols

Eleftherios Ioannidis1, Kathy S. Law1, Jean-Christophe Raut1, Louis Marelle1, Tatsuo Onishi1, Rachel M. Kirpes2, Lucia Upchurch3, Andreas Massling4, Henrik Skov4, Patricia K. Quinn3, and Kerri A. Pratt2,5 Eleftherios Ioannidis et al.
  • 1LATMOS/IPSL, Sorbonne Université, UVSQ, CNRS, Paris, France
  • 2Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
  • 3Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington 98115, United States
  • 4Department of Environmental Science, iClimate, Aarhus University, Denmark
  • 5Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA

Abstract. Anthropogenic and natural emissions contribute to enhanced concentrations of aerosols, so-called Arctic Haze in the Arctic winter and early spring. Models still have difficulties reproducing available observations. Whilst most attention has focused on the contribution of anthropogenic aerosols, there has been less focus on natural components such as sea-spray aerosols (SSA), including sea-salt sulphate and marine organics, which can make an important contribution to fine and coarse mode aerosols, particularly in coastal areas. Models tend to underestimate sub-micron and overestimate super-micron SSA in polar regions, including in the Arctic region. Quasi-hemispheric runs of the Weather Research Forecast model, coupled with chemistry model (WRF-Chem) are compared to aerosol composition data at remote Arctic sites to evaluate the model performance simulating wintertime Arctic Haze. Results show that the model overestimates sea-salt (sodium and chloride) and nitrate and underestimates sulphate aerosols. Inclusion of more recent wind-speed and sea-surface temperature dependencies for sea-salt emissions, as well as inclusion of marine organic and sea-salt sulphate aerosol emissions leads to better agreement with the observations during wintertime. The model captures better the contribution of SSA to total mass for different aerosol modes, ranging from 20–93 % in the observations. The sensitivity of modelled SSA to processes influencing SSA production are examined in regional runs over northern Alaska (United States) where the model underestimates episodes of high SSA, particularly in the sub-micron, that were observed in winter 2014 during field campaigns at the Barrow Observatory, Utqiaġvik. A local source of marine organics is also included following previous studies showing evidence for an important contribution from marine emissions. Model results show relatively small sensitivity to aerosol dry removal with more sensitivity (improved biases) to using a higher wind speed dependence based on sub-micron data reported from an Arctic cruise. Sea-ice fraction, including sources from open leads, is shown to be a more important factor controlling modelled super-micron SSA than sub-micron SSA. The findings of this study support analysis of the field campaign data pointing out that open leads are the primary source of SSA, including marine organic aerosols during wintertime at the Barrow Observatory, Utqiaġvik. Nevertheless, episodes of high observed SSA are still underestimated by the model at this site, possibly due to missing sources such as SSA production from breaking waves. An analysis of the observations and model results does not suggest an influence from blowing snow and frost flowers to SSA during the period of interest. Reasons for the high concentrations of sub-micron SSA observed at this site, higher than other Arctic sites, require further investigation.

Eleftherios Ioannidis et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Review of egusphere-2022-310', Øystein Hov, 23 Jun 2022
  • RC1: 'Comment on egusphere-2022-310', Anonymous Referee #1, 06 Aug 2022
  • RC2: 'Comment on egusphere-2022-310', Anonymous Referee #2, 24 Aug 2022

Eleftherios Ioannidis et al.

Eleftherios Ioannidis et al.

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Short summary
Enhanced concentrations of aerosols influence the Arctic region during wintertime and winter-spring transition, transported from mid-latitude source regions. However, there are also local anthropogenic and natural (sea-spray aerosols – SSA) sources. SSA are a major contributor to PM1.0/PM10 at remote coastal sites during wintertime, however, models tend to miss essential mechanisms for SSA production and local sources of marine organics in the Arctic. This study addresses these uncertainties.