Preprints
https://doi.org/10.5194/egusphere-2022-1074
https://doi.org/10.5194/egusphere-2022-1074
21 Oct 2022
 | 21 Oct 2022

Source Mechanisms and transport Patterns of tropospheric BrO: Findings from long-term MAX-DOAS Measurements at two Antarctic Stations

Udo Frieß, Karin Kreher, Richard Querel, Holger Schmithüsen, Dan Smale, Rolf Weller, and Ulrich Platt

Abstract. The presence of reactive bromine in Polar Regions is a widespread phenomenon that plays an important role in the photochemistry of the Arctic and Antarctic lower troposphere, including the destruction of ozone, the disturbance of radical cycles, and the oxidation of gaseous elemental mercury. The chemical mechanisms leading to the heterogeneous release of gaseous bromine compounds from saline surfaces are in principle well understood. There are, however, substantial uncertainties about the contribution of different potential sources to the release of reactive bromine, such as sea ice, brine, aerosols and the snow surface, as well as about the seasonal and diurnal variation and the vertical distribution of reactive bromine. Here we use continuous long-term measurements of the vertical distribution of bromine monoxide (BrO) and aerosols at the two Antarctic sites Neumayer (NM) and Arrival Heights (AH), covering the periods of 2003–2021 and 2012–2021, respectively, to investigate how chemical and physical parameters affect the abundance of BrO. We find the strongest correlation between BrO and aerosol extinction (R = 0.56 for NM and R = 0.28 for AH during spring), suggesting that the heterogeneous release of Br2 from saline airborne particles (blowing snow and aerosols) is a dominant source for reactive bromine. Positive correlations between BrO and contact time of air masses both, with sea ice and the Antarctic ice sheet suggest that reactive bromine is not only emitted by the sea ice surface, but by the snowpack on the ice shelf and in the coastal regions of Antarctica. In addition, the open ocean appears to represent a source for reactive bromine during late summer and autumn when the sea ice extent is at its minimum. A source-receptor analysis based on back trajectories together with sea ice maps shows that main source regions for BrO at NM is the Weddell Sea and the Filchner-Ronne Ice Shelf, as well as coastal polynias where sea ice is newly formed. A strong morning peak in BrO frequently occuring during summer, and particular during autumn, suggests a night-time built up of Br2 by heterogeneous reaction of ozone on the saline snow pack in the vicinity of the measurement sites. We furthermore show that BrO can be sustained for several days while travelling across the Antarctic continent in the absence of any saline surfaces that could serve as a source for reactive bromine.

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Journal article(s) based on this preprint

10 Mar 2023
Source mechanisms and transport patterns of tropospheric bromine monoxide: findings from long-term multi-axis differential optical absorption spectroscopy measurements at two Antarctic stations
Udo Frieß, Karin Kreher, Richard Querel, Holger Schmithüsen, Dan Smale, Rolf Weller, and Ulrich Platt
Atmos. Chem. Phys., 23, 3207–3232, https://doi.org/10.5194/acp-23-3207-2023,https://doi.org/10.5194/acp-23-3207-2023, 2023
Short summary
Udo Frieß, Karin Kreher, Richard Querel, Holger Schmithüsen, Dan Smale, Rolf Weller, and Ulrich Platt

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1074', Anonymous Referee #1, 13 Nov 2022
  • RC2: 'Comment on egusphere-2022-1074', Anonymous Referee #2, 16 Nov 2022
  • AC1: 'Reply to reviewer comments on egusphere-2022-1074', Udo Friess, 13 Jan 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1074', Anonymous Referee #1, 13 Nov 2022
  • RC2: 'Comment on egusphere-2022-1074', Anonymous Referee #2, 16 Nov 2022
  • AC1: 'Reply to reviewer comments on egusphere-2022-1074', Udo Friess, 13 Jan 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Udo Friess on behalf of the Authors (13 Jan 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (21 Jan 2023) by Michel Van Roozendael
RR by Anonymous Referee #2 (25 Jan 2023)
RR by Anonymous Referee #1 (04 Feb 2023)
ED: Publish subject to technical corrections (12 Feb 2023) by Michel Van Roozendael
AR by Udo Friess on behalf of the Authors (17 Feb 2023)  Author's response   Manuscript 

Journal article(s) based on this preprint

10 Mar 2023
Source mechanisms and transport patterns of tropospheric bromine monoxide: findings from long-term multi-axis differential optical absorption spectroscopy measurements at two Antarctic stations
Udo Frieß, Karin Kreher, Richard Querel, Holger Schmithüsen, Dan Smale, Rolf Weller, and Ulrich Platt
Atmos. Chem. Phys., 23, 3207–3232, https://doi.org/10.5194/acp-23-3207-2023,https://doi.org/10.5194/acp-23-3207-2023, 2023
Short summary
Udo Frieß, Karin Kreher, Richard Querel, Holger Schmithüsen, Dan Smale, Rolf Weller, and Ulrich Platt
Udo Frieß, Karin Kreher, Richard Querel, Holger Schmithüsen, Dan Smale, Rolf Weller, and Ulrich Platt

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Short summary
Reactive bromine compounds, emitted by the sea ice during polar spring, play an important role in the atmospheric chemistry of the coastal regions of Antarctica. We investigate the sources and impacts of reactive bromine in detail using many years of measurements at two Antarctic sites, located at opposite sides of the Antarctic continent. Using a multitude of meteorological observations, we were able to identify the main triggers and source regions for reactive bromine in Antarctica.