Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Extensive halogen-mediated ozone destruction over the tropical Atlantic Ocean

An Author Correction to this article was published on 19 June 2024

This article has been updated


Increasing tropospheric ozone levels over the past 150 years have led to a significant climate perturbation1; the prediction of future trends in tropospheric ozone will require a full understanding of both its precursor emissions and its destruction processes. A large proportion of tropospheric ozone loss occurs in the tropical marine boundary layer2,3 and is thought to be driven primarily by high ozone photolysis rates in the presence of high concentrations of water vapour. A further reduction in the tropospheric ozone burden through bromine and iodine emitted from open-ocean marine sources has been postulated by numerical models4,5,6,7, but thus far has not been verified by observations. Here we report eight months of spectroscopic measurements at the Cape Verde Observatory indicative of the ubiquitous daytime presence of bromine monoxide and iodine monoxide in the tropical marine boundary layer. A year-round data set of co-located in situ surface trace gas measurements made in conjunction with low-level aircraft observations shows that the mean daily observed ozone loss is 50 per cent greater than that simulated by a global chemistry model using a classical photochemistry scheme that excludes halogen chemistry. We perform box model calculations that indicate that the observed halogen concentrations induce the extra ozone loss required for the models to match observations. Our results show that halogen chemistry has a significant and extensive influence on photochemical ozone loss in the tropical Atlantic Ocean boundary layer. The omission of halogen sources and their chemistry in atmospheric models may lead to significant errors in calculations of global ozone budgets, tropospheric oxidizing capacity and methane oxidation rates, both historically and in the future.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Example data from aircraft observations 1–20 km upwind of São Vicente.
Figure 2: Measurements and modelling results.
Figure 3: Halogen oxide observations.
Figure 4: Monthly averaged contributions to the daily ozone budgets between 09:00 and 17:00 ut.

Similar content being viewed by others

Change history


  1. Intergovernmental. Panel on Climate Change (IPCC) Climate Change 2007: The Physical Sciences Basis, available at 〈〉 (Retrieved on 30 April 2007.).

  2. Horowitz, L. W. et al. A global simulation of tropospheric ozone and related tracers: Description and evaluation of MOZART, version 2. J. Geophys. Res. 108 (D24). 4784–4812 (2003)

    Google Scholar 

  3. Lawrence, M. G., Jockel, P. & von Kuhlmann, R. What does the global mean OH concentration tell us? Atmos. Chem. Phys. 1, 37–49 (2001)

    Article  ADS  CAS  Google Scholar 

  4. Vogt, R., Sander, R., von Glasow, R. & Crutzen, P. J. Iodine chemistry and its role in halogen activation and ozone loss in the marine boundary layer: A model study. J. Atmos. Chem. 32, 375–395 (1999)

    Article  CAS  Google Scholar 

  5. von Glasow, R., von Kuhlmann, R., Lawrence, M. G., Platt, U. & Crutzen, P. J. Impact of reactive bromine chemistry in the troposphere. Atmos. Chem. Phys. 4, 2481–2497 (2004)

    Article  ADS  CAS  Google Scholar 

  6. Yang, X. et al. Tropospheric bromine chemistry and its impacts on ozone: A model study. J. Geophys. Res. 110, D23311 (2005)

    ADS  Google Scholar 

  7. von Glasow, R., Sander, R., Bott, A. & Crutzen, P. J. Modelling halogen chemistry in the marine boundary layer. 1. Cloud-free MBL. J. Geophys. Res. 107 (D17). 4341–4356 (2002)

    Google Scholar 

  8. Junge, C. E. Global ozone budget and exchange between stratosphere and troposphere. Tellus 14, 363–377 (1962)

    Article  ADS  Google Scholar 

  9. Lelieveld, J. et al. Increasing ozone over the Atlantic Ocean. Science 304, 1483–1487 (2004)

    Article  ADS  CAS  PubMed  Google Scholar 

  10. Bloss, W. J. et al. The oxidative capacity of the troposphere: Coupling of field measurements of OH and a global chemistry transport model. Faraday Discuss. 130, 425–436 (2005)

    Article  ADS  CAS  PubMed  Google Scholar 

  11. Falkowski, P. G. Evolution of the nitrogen cycle and its influence on the biological sequestration of CO2 in the ocean. Nature 387, 272–274 (1997)

    Article  ADS  CAS  Google Scholar 

  12. Simmonds, P. G., Derwent, R. G., Manning, A. L. & Spain, G. Significant growth in surface ozone at Mace Head, Ireland, 1987–2003. Atmos. Environ. 38, 4769–4778 (2004)

    Article  ADS  CAS  Google Scholar 

  13. Parrish, D. D. et al. Relationships between ozone and carbon monoxide at surface sites in the North Atlantic region. J. Geophys. Res. 103 (D11). 13357–13376 (1998)

    Article  ADS  CAS  Google Scholar 

  14. Bey, I. et al. Global modeling of tropospheric chemistry with assimilated meteorology: Model description and evaluation. J. Geophys. Res. 106, 23073–23095 (2001)

    Article  ADS  CAS  Google Scholar 

  15. Wild, O., Zhu, X. & Prather, M. J. Fast-J: accurate simulation of in- and below-cloud photolysis in tropospheric chemical models. J. Atmos. Chem. 37, 245–282 (2004)

    Article  Google Scholar 

  16. Galbally, I. E., Bentley, S. T. & Meyer, C. P. Mid-latitude marine boundary-layer ozone destruction at visible sunrise observed at Cape Grim, Tasmania, 41 degrees S. Geophys. Res. Lett. 27, 3841–3844 (2000)

    Article  ADS  CAS  Google Scholar 

  17. Dickerson, R. R. et al. Ozone in the remote marine boundary layer: A possible role for halogens. J. Geophys. Res. 104, 21385–21396 (1999)

    Article  ADS  CAS  Google Scholar 

  18. Allan, B. J., McFiggans, G., Plane, J. M. C. & Coe, H. The nitrate radical in the remote marine boundary layer. J. Geophys. Res. 105, 24191–24204 (2000)

    Article  ADS  Google Scholar 

  19. Leser, H., Honninger, G. & Platt, U. MAX-DOAS measurements of BrO and NO2 in the marine boundary layer. Geophys. Res. Lett. 30, art. no. 1537 (2003)

  20. Sander, R., Rudich, Y., von Glasow, R. & Crutzen, P. J. The role of BrNO3 in marine tropospheric chemistry: A model study. Geophys. Res. Lett. 26, 2857–2860 (1999)

    Article  ADS  CAS  Google Scholar 

  21. Toumi, R. BrO as a sink for dimethylsulfide in the marine atmosphere. Geophys. Res. Lett. 21, 117–120 (1994)

    Article  ADS  CAS  Google Scholar 

  22. Vogt, R., Crutzen, P. J. & Sander, R. A mechanism for halogen release from sea-salt aerosol in the remote marine boundary layer. Nature 383, 327–330 (1996)

    Article  ADS  CAS  Google Scholar 

  23. Plane, J. M. C. & Saiz-Lopez, A. in Analytical Techniques for Atmospheric Measurement (ed. Heard, D. E.) (Blackwell, Oxford, 2006)

    Google Scholar 

  24. Platt, U. in Air Monitoring by Spectroscopy Techniques (ed. Sigrist, M. W.) 27–83 (Wiley, London, 1994)

    Google Scholar 

  25. Davis, D. et al. South Pole NO x Chemistry: An assessment of factors controlling variability and absolute levels. Atmos. Environ. 38, 5375–5388 (2004)

    Article  ADS  CAS  Google Scholar 

  26. Hopkins, J. R., Lewis, A. C. & Read, K. A. A two-column method for long-term monitoring of non-methane hydrocarbons (NMHCs) and oxygenated volatile organic compounds (o-VOCs). J. Environ. Monit. 4, 1–7 (2002)

    Google Scholar 

Download references


We thank pilots C. Joseph and D. Davies from the NERC Airborne Research and Support Facility, Oxford, for their assistance in obtaining the vertically resolved observations. We thank M. Heimann for provision of CH4 data from the Cape Verde Observatory and K. Furneaux and L. Whalley for provision of J(O1D) data. We acknowledge the UK NERC Surface Ocean Lower Atmosphere programme and the EU (Tropical Eastern North Atlantic Time Series Observatory) for funding. Finally, we thank D. Wallace, M. Heimann, J. Pimenta Lima and O. Melicio for their roles in setting up the Cape Verde Observatory, and G. McFiggans for conception of the Reactive Halogens in the Marine Boundary Layer Experiment, which contributed to this paper.

Author Contributions L.J.C, J.M.C.P, M.J.P. and A.C.L. conceived the experiment, and together with K.A.R., A.S.M., B.V.E.F., D.E.H., J.R.H., J.D.L, S.J.M, L.M., J.B.M., H.O. and A.S.-L. carried it out; L.J.C., M.J.E and K.A.R. carried out the data analysis; L.J.C., A.C.L, M.J.E and K.A.R. wrote the paper.

Author information

Authors and Affiliations


Corresponding authors

Correspondence to Lucy J. Carpenter or John M. C. Plane.

Supplementary information

Supplementary Information

The file contains Supplementary Figures S1-S5 with Legends, Supplementary Methods, Supplementary Table 1 and additional references. (PDF 2780 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Read, K., Mahajan, A., Carpenter, L. et al. Extensive halogen-mediated ozone destruction over the tropical Atlantic Ocean. Nature 453, 1232–1235 (2008).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing