Articles | Volume 17, issue 12
Atmos. Chem. Phys., 17, 7567–7579, 2017
Atmos. Chem. Phys., 17, 7567–7579, 2017

Research article 22 Jun 2017

Research article | 22 Jun 2017

Observations of bromine monoxide transport in the Arctic sustained on aerosol particles

Peter K. Peterson1, Denis Pöhler2, Holger Sihler2,3, Johannes Zielcke2, Stephan General2, Udo Frieß2, Ulrich Platt2,3, William R. Simpson4, Son V. Nghiem5, Paul B. Shepson6, Brian H. Stirm7, Suresh Dhaniyala8, Thomas Wagner3, Dana R. Caulton9, Jose D. Fuentes10, and Kerri A. Pratt1,11 Peter K. Peterson et al.
  • 1Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
  • 2Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany
  • 3Max Planck Institute for Chemistry, Mainz, Germany
  • 4Department of Chemistry and Biochemistry and Geophysical Institute, University of Alaska Fairbanks, Fairbanks, Alaska, USA
  • 5Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
  • 6Department of Chemistry, Department of Earth, Planetary, and Atmospheric Sciences, and Purdue Climate Change Research Center, Purdue University, West Lafayette, IN, USA
  • 7School of Aviation and Transportation Technology, Purdue University, West Lafayette, IN, USA
  • 8Department of Mechanical and Aeronautical Engineering, Clarkson University, Potsdam, NY, USA
  • 9Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
  • 10Department of Meteorology, The Pennsylvania State University, University Park, PA, USA
  • 11Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA

Abstract. The return of sunlight in the polar spring leads to the production of reactive halogen species from the surface snowpack, significantly altering the chemical composition of the Arctic near-surface atmosphere and the fate of long-range transported pollutants, including mercury. Recent work has shown the initial production of reactive bromine at the Arctic surface snowpack; however, we have limited knowledge of the vertical extent of this chemistry, as well as the lifetime and possible transport of reactive bromine aloft. Here, we present bromine monoxide (BrO) and aerosol particle measurements obtained during the March 2012 BRomine Ozone Mercury EXperiment (BROMEX) near Utqiaġvik (Barrow), AK. The airborne differential optical absorption spectroscopy (DOAS) measurements provided an unprecedented level of spatial resolution, over 2 orders of magnitude greater than satellite observations and with vertical resolution unable to be achieved by satellite methods, for BrO in the Arctic. This novel method provided quantitative identification of a BrO plume, between 500 m and 1 km aloft, moving at the speed of the air mass. Concurrent aerosol particle measurements suggest that this lofted reactive bromine plume was transported and maintained at elevated levels through heterogeneous reactions on colocated supermicron aerosol particles, independent of surface snowpack bromine chemistry. This chemical transport mechanism explains the large spatial extents often observed for reactive bromine chemistry, which impacts atmospheric composition and pollutant fate across the Arctic region, beyond areas of initial snowpack halogen production. The possibility of BrO enhancements disconnected from the surface potentially contributes to sustaining BrO in the free troposphere and must also be considered in the interpretation of satellite BrO column observations, particularly in the context of the rapidly changing Arctic sea ice and snowpack.

Short summary
High-spatial-resolution aircraft measurements in the Arctic showed the sustained transport of reactive bromine in a lofted layer via heterogeneous reactions on aerosol particles. This process provides an explanation for free tropospheric reactive bromine and the significant spatial extent of satellite-observed bromine monoxide. The knowledge gained herein improves our understanding of the fate and transport of atmospheric pollutants in the Arctic.
Final-revised paper