Preprints
https://doi.org/10.5194/acp-2021-202
https://doi.org/10.5194/acp-2021-202

  30 Mar 2021

30 Mar 2021

Review status: this preprint is currently under review for the journal ACP.

Organic and inorganic bromine measurements around the extratropical tropopause and lowermost stratosphere: Insights into the transport pathways and total bromine

Meike K. Rotermund1, Vera Bense2, Martyn P. Chipperfield3,4, Andreas Engel5, Jens-Uwe Grooß6, Peter Hoor2, Tilman Hüneke1,a, Timo Keber5, Flora Kluge1, Benjamin Schreiner1, Tanja Schuck5, Bärbel Vogel6, Andreas Zahn7, and Klaus Pfeilsticker1 Meike K. Rotermund et al.
  • 1Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany
  • 2Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany
  • 3School of Earth and Environment, University of Leeds, Leeds, UK
  • 4National Centre for Earth Observation, University of Leeds, Leeds, UK
  • 5Institute for Atmospheric and Environmental Science, Goethe University Frankfurt, Frankfurt, Germany
  • 6Institute of Energy and Climate Research - Stratosphere (IEK-7), Forschungszentrum Jülich, Jülich, Germany
  • 7Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
  • anow at: Encavis AG, Hamburg, Germany

Abstract. We report on measurements of total bromine (Brtot) in the upper troposphere and lower stratosphere taken during 15 flights with the German High Altitude and LOng range research aircraft (HALO). The research campaign WISE (Wave-driven ISentropic Exchange) included regions over the North Atlantic, Norwegian Sea and north-western Europe in fall 2017. Brtot is calculated from measured total organic bromine (Brorg) added to inorganic bromine (Bryinorg), evaluated from measured BrO and photochemical modelling. Combining these data, the weighted-mean [Brtot] is 19.2 ± 1.2 ppt in the northern hemispheric lower stratosphere (LS) in agreement with expectations for Brtot in the middle stratosphere (Engel and Rigby et al. (2018)). The data reflects the expected variability in Brtot in the LS due to variable influx of shorter-lived brominated source and product gases from different regions of entry. A closer look into Brorg and Bryinorg, as well as simultaneously measured transport tracers (CO and N2O) and an air mass lag-time tracer (SF6), suggests that bromine-rich air masses persistently protruded into the lowermost stratosphere (LMS) in boreal summer, creating a high bromine region (HBrR). A subsection, HBrR*, has a weighted average of [Brtot] = 20.9 ± 0.8 ppt. The most probable source region is former air from the tropical upper troposphere and tropopause layer (UT/TTL) with a weighted mean [Brtot] = 21.6 ± 0.7 ppt. CLaMS Lagrangian transport modelling shows that the HBrR air mass consists of 51.2 % from the tropical troposphere, 27.1 % from the stratospheric background, and 6.4 % from the mid-latitude troposphere (as well as contributions from other domains). The majority of the surface air reaching the HBrR is from the Asian monsoon and its adjacent tropical regions, which greatly influences trace gas transport into the LMS in boreal summer and fall. Tropical cyclones from Central America in addition to air associated with the Asian monsoon region contribute to the elevated Brtot observed in the UT/TTL. TOMCAT global 3–D model simulations of a concurrent increase of Brtot show an associated O3 change of −2.6 ± 0.7 % in the LS and −3.1 ± 0.7 % near the tropopause. Our study of varying Brtot in the LS also emphasizes the need for more extensive monitoring of stratospheric Brtot globally and seasonally to fully understand its impact on LMS O3 and its radiative forcing of climate, as well as in aged air in the middle stratosphere to elucidate the stratospheric trend in bromine.

Meike K. Rotermund et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on acp-2021-202', Johannes Orphal, 12 Apr 2021
    • AC1: 'Reply on CC1', Meike Rotermund, 12 Apr 2021
  • RC1: 'Comment on acp-2021-202', Anonymous Referee #1, 11 Jun 2021
  • RC2: 'Comment on acp-2021-202', Qing Liang, 16 Jun 2021

Meike K. Rotermund et al.

Meike K. Rotermund et al.

Viewed

Total article views: 498 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
358 130 10 498 5 6
  • HTML: 358
  • PDF: 130
  • XML: 10
  • Total: 498
  • BibTeX: 5
  • EndNote: 6
Views and downloads (calculated since 30 Mar 2021)
Cumulative views and downloads (calculated since 30 Mar 2021)

Viewed (geographical distribution)

Total article views: 497 (including HTML, PDF, and XML) Thereof 497 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 18 Jun 2021
Download
Short summary
Airborne total bromine (Brtot) and tracer measurements suggest that Brtot-rich air masses persistently protruded into the lower stratosphere (LS) creating a high Brtot region over the North Atlantic in fall 2017. The main sources are former tropical upper tropospheric air transported by the Asian monsoon and hurricanes from Central America, and to a lesser extent transport across the extratropical tropopause as quantified by a Lagrange model. Consequences of Brtot on LS ozone are also assessed.
Altmetrics