ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-12-10633-2012 Emission and transport of bromocarbons: from the West Pacific ocean into the stratosphere Tegtmeier S. 1 Krüger K. 1 Quack B. 1 Atlas E. L. 2 Pisso I. 3 Stohl A. 4 Yang X. 5 6 GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, USA Research Institute for Global Change, JAMSTEC, Yokohama, Japan Norwegian Institute for Air Research (NILU), Kjeller, Norway National Centre for Atmospheric Science (NCAS-Climate), Cambridge, UK Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, Cambridge, UK 16 11 2012 12 22 10633 10648 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/12/10633/2012/acp-12-10633-2012.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/10633/2012/acp-12-10633-2012.pdf

Oceanic emissions of halogenated very short-lived substances (VSLS) are expected to contribute significantly to the stratospheric halogen loading and therefore to ozone depletion. The amount of VSLS transported into the stratosphere is estimated based on in-situ observations around the tropical tropopause layer (TTL) and on modeling studies which mostly use prescribed global emission scenarios to reproduce observed atmospheric concentrations. In addition to upper-air VSLS measurements, direct observations of oceanic VSLS emissions are available along ship cruise tracks. Here we use such in-situ observations of VSLS emissions from the West Pacific and tropical Atlantic together with an atmospheric Lagrangian transport model to estimate the direct contribution of bromoform (CHBr<sub>3</sub>), and dibromomethane (CH<sub>2</sub>Br<sub>2</sub>) to the stratospheric bromine loading as well as their ozone depletion potential. Our emission-based estimates of VSLS profiles are compared to upper-air observations and thus link observed oceanic emissions and in situ TTL measurements. This comparison determines how VSLS emissions and transport in the cruise track regions contribute to global upper-air VSLS estimates. The West Pacific emission-based profiles and the global upper-air observations of CHBr<sub>3</sub> show a relatively good agreement indicating that emissions from the West Pacific provide an average contribution to the global CHBr<sub>3</sub> budget. The tropical Atlantic, although also being a CHBr<sub>3</sub> source region, is of less importance for global upper-air CHBr<sub>3</sub> estimates as revealed by the small emission-based abundances in the TTL. Western Pacific CH<sub>2</sub>Br<sub>2</sub> emission-based estimates are considerably smaller than upper-air observations as a result of the relatively low sea-to-air flux found in the West Pacific. Together, CHBr<sub>3</sub> and CH<sub>2</sub>Br<sub>2</sub> emissions from the West Pacific are projected to contribute to the stratospheric bromine budget with 0.4 pptv Br on average and 2.3 pptv Br for cases of maximum emissions through product and source gas injection. These relatively low estimates reveal that the tropical West Pacific, although characterized by strong convective transport, might overall contribute less VSLS to the stratospheric bromine budget than other regions as a result of only low CH<sub>2</sub>Br<sub>2</sub> and moderate CHBr<sub>3</sub> oceanic emissions.

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