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
Received: 02 Sep 2011 – Discussion started: 06 Dec 2011
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.
Revised: 01 Mar 2012 – Accepted: 12 Apr 2012 – Published: 04 May 2012
Saiz-Lopez, A., Lamarque, J.-F., Kinnison, D. E., Tilmes, S., Ordóñez, C., Orlando, J. J., Conley, A. J., Plane, J. M. C., Mahajan, A. S., Sousa Santos, G., Atlas, E. L., Blake, D. R., Sander, S. P., Schauffler, S., Thompson, A. M., and Brasseur, G.: Estimating the climate significance of halogen-driven ozone loss in the tropical marine troposphere, Atmos. Chem. Phys., 12, 3939-3949, doi:10.5194/acp-12-3939-2012, 2012.