Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 15, 13647-13663, 2015
http://www.atmos-chem-phys.net/15/13647/2015/
doi:10.5194/acp-15-13647-2015
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
10 Dec 2015
Oceanic bromoform emissions weighted by their ozone depletion potential
S. Tegtmeier1, F. Ziska1, I. Pisso2, B. Quack1, G. J. M. Velders3, X. Yang4, and K. Krüger5 1GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
2Norwegian Institute for Air Research (NILU), Kjeller, Norway
3National Institute for Public Health and the Environment, Bilthoven, the Netherlands
4British Antarctic Survey, Cambridge, UK
5University of Oslo, Oslo, Norway
Abstract. At present, anthropogenic halogens and oceanic emissions of very short-lived substances (VSLSs) both contribute to the observed stratospheric ozone depletion. Emissions of the long-lived anthropogenic halogens have been reduced and are currently declining, whereas emissions of the biogenic VSLSs are expected to increase in future climate due to anthropogenic activities affecting oceanic production and emissions. Here, we introduce a new approach for assessing the impact of oceanic halocarbons on stratospheric ozone by calculating their ozone depletion potential (ODP)-weighted emissions. Seasonally and spatially dependent, global distributions are derived within a case-study framework for CHBr3 for the period 1999–2006. At present, ODP-weighted emissions of CHBr3 amount up to 50 % of ODP-weighted anthropogenic emissions of CFC-11 and to 9 % of all long-lived ozone depleting halogens. The ODP-weighted emissions are large where strong oceanic emissions coincide with high-reaching convective activity and show pronounced peaks at the Equator and the coasts with largest contributions from the Maritime Continent and western Pacific Ocean. Variations of tropical convective activity lead to seasonal shifts in the spatial distribution of the trajectory-derived ODP with the updraught mass flux, used as a proxy for trajectory-derived ODP, explaining 71 % of the variance of the ODP distribution. Future climate projections based on the RCP 8.5 scenario suggest a 31 % increase of the ODP-weighted CHBr3 emissions by 2100 compared to present values. This increase is related to a larger convective updraught mass flux in the upper troposphere and increasing emissions in a future climate. However, at the same time, it is reduced by less effective bromine-related ozone depletion due to declining stratospheric chlorine concentrations. The comparison of the ODP-weighted emissions of short- and long-lived halocarbons provides a new concept for assessing the overall impact of oceanic halocarbon emissions on stratospheric ozone depletion for current conditions and future projections.

Citation: Tegtmeier, S., Ziska, F., Pisso, I., Quack, B., Velders, G. J. M., Yang, X., and Krüger, K.: Oceanic bromoform emissions weighted by their ozone depletion potential, Atmos. Chem. Phys., 15, 13647-13663, doi:10.5194/acp-15-13647-2015, 2015.
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Short summary
At present, man-made halogens and natural oceanic substances both contribute to the observed ozone depletion. Emissions of the anthropogenic halogens have been reduced, whereas emissions of the natural substances are expected to increase in future climate due to anthropogenic activities affecting oceanic processes. We assess the impact of these oceanic substances on ozone by weighting their emissions with their potential to destroy ozone for current conditions and future projections.
At present, man-made halogens and natural oceanic substances both contribute to the observed...
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