Comparison of model and ground observations finds snowpack and blowing snow both contribute to Arctic tropospheric reactive bromine

• Main Authors: Swanson, William, Holmes, Chris, Simpson, William, Confer, Kaitlyn, Marelle, Louis, Thomas, Jennie, Jaeglé, Lyatt, Alexander, Becky, Zhai, Shuting, Chen, Qianjie, Wang, Xuan, Sherwen, Tomás
• Other Authors: Department of Chemistry and Biochemistry Fairbanks, University of Alaska Fairbanks (UAF), Geophysical Institute Fairbanks, Department of Earth, Ocean and Atmospheric Science Tallahassee (FSU, Florida State University Tallahassee (FSU), Department of Atmospheric Sciences Seattle, University of Washington Seattle, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Civil and Environmental Engineering Hong Kong (CEE), The Hong Kong Polytechnic University Hong Kong (POLYU), School of Energy and Environment Hong Kong, City University of Hong Kong Hong Kong (CUHK), National Centre for Atmospheric Science York (NCAS), University of York York, UK, Department of Chemistry York, UK
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Arctic; Sea ice; Alaska
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-03578658; https://hal-insu.archives-ouvertes.fr/insu-03578658/document; https://hal-insu.archives-ouvertes.fr/insu-03578658/file/acp-2022-44.pdf; https://doi.org/10.5194/acp-2022-44

International audience Reactive halogens play a prominent role in the atmospheric chemistry of the Arctic during springtime. Field measurements and models studies suggest that halogens are emitted to the atmosphere from snowpack and reactions on wind-blown snow. The relative importance of snowpack and blowing snow sources is still debated, both at local scales and regionally throughout the Arctic. To understand implications of these halogen sources on a pan-Arctic scale, we simulate Arctic reactive bromine chemistry in the atmospheric chemical transport model GEOS-Chem. Two mechanisms are included: 1) a blowing snow sea salt aerosol formation mechanism and 2) a snowpack mechanism assuming uniform molecular bromine production from all snow surfaces. We compare simulations including neither mechanism, each mechanism individually, and both mechanisms to examine conditions where one process may dominate or the mechanisms may interact. We compare the models using these mechanisms to observations of bromine monoxide (BrO) derived from multiple-axis differential optical absorption spectroscopy (MAX-DOAS) instruments on O-Buoy platforms on the sea ice and at a coastal site in Utqiaġvik, Alaska during spring 2015. Model estimations of hourly and monthly average BrO are improved by assuming a constant yield of 0.1% molecular bromine from all snowpack surfaces on ozone deposition. The blowing snow mechanism increases BrO by providing more surface area for reactive