Articles | Volume 12, issue 9
Atmos. Chem. Phys., 12, 3939–3949, 2012
Atmos. Chem. Phys., 12, 3939–3949, 2012

Research article 04 May 2012

Research article | 04 May 2012

Estimating the climate significance of halogen-driven ozone loss in the tropical marine troposphere

A. Saiz-Lopez1, J.-F. Lamarque2, D. E. Kinnison2, S. Tilmes2, C. Ordóñez1, J. J. Orlando2, A. J. Conley2, J. M. C. Plane3, A. S. Mahajan1, G. Sousa Santos4, E. L. Atlas5, D. R. Blake6, S. P. Sander7, S. Schauffler8, A. M. Thompson9, and G. Brasseur10 A. Saiz-Lopez et al.
  • 1Laboratory for Atmospheric and Climate Science, CSIC, Toledo, Spain
  • 2Atmospheric Chemistry Division, NCAR, Boulder, CO, USA
  • 3School of Chemistry, University of Leeds, Leeds, UK
  • 4Institute for Atmospheric and Climate Science, ETH, Zurich, Switzerland
  • 5Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA
  • 6Department of Chemistry, University of California, Irvine, CA, USA
  • 7Jet Propulsion Laboratory, California Institute of Technology, CA, USA
  • 8Earth Observing Laboratory, NCAR, Boulder, CO, USA
  • 9Department of Meteorology, Pennsylvania State University, Pennsylvania, USA
  • 10Climate Service Center, Hamburg, Germany

Abstract. We have integrated observations of tropospheric ozone, very short-lived (VSL) halocarbons and reactive iodine and bromine species from a wide variety of tropical data sources with the global CAM-Chem chemistry-climate model and offline radiative transfer calculations to compute the contribution of halogen chemistry to ozone loss and associated radiative impact in the tropical marine troposphere. The inclusion of tropospheric halogen chemistry in CAM-Chem leads to an annually averaged depletion of around 10% (~2.5 Dobson units) of the tropical tropospheric ozone column, with largest effects in the middle to upper troposphere. This depletion contributes approximately −0.10 W m−2 to the radiative flux at the tropical tropopause. This negative flux is of similar magnitude to the ~0.33 W m−2 contribution of tropospheric ozone to present-day radiative balance as recently estimated from satellite observations. We find that the implementation of oceanic halogen sources and chemistry in climate models is an important component of the natural background ozone budget and we suggest that it needs to be considered when estimating both preindustrial ozone baseline levels and long term changes in tropospheric ozone.

Final-revised paper