Journal of Atmospheric Chemistry

, Volume 25, Issue 3, pp 271–288 | Cite as

Changing trends in tropospheric methane and carbon monoxide: A sensitivity analysis of the OH-radical

  • Han Van Dop
  • Maarten Krol


A sensitivity analysis is performed in order to study recently observed changes in atmospheric methane and carbon monoxide trends. For the analysis we have adapted a one-dimensional transport/chemistry model in order to comply with changes in vertical transport, stratosphere-troposphere flux of ozone, the water vapour cycle and the short-wave radiative transfer. In addition we have formulated an improved relationship which expresses the steady state OH concentration in terms of longer lived compounds which has a fair agreement with the one-dimensional model results. An analysis of the observed changes and trends in methane and carbon monoxide shows that both emissions and changes in global OH concentrations can be main causes for the observed changes. Average methane emissions have slowed down, particularly in the NH, in the last five years, though perhaps not very significantly. Carbon monoxide emissions are decreasing faster in the last couple of years than in the period 1983–1990. The study suggests that climate fluctuations (tropospheric water vapour, temperature and convective activity) and the stratospheric ozone depletion (tropospheric UV radiation) have a significant influence on tropospheric composition and thus on trends in methane and carbon monoxide concentrations.

Key words

tropospheric chemistry hydroxyl radical UV-radiation 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Albritton, D. L., Watson, R. T., and Aucamp, P. J.: 1995, Scientific Assessment of the Ozone Depletion: 1994, WMO report no. 37, Geneva.Google Scholar
  2. BakwinP. S., TansP. P., and NovelliP. C.: 1994, Carbon monoxide budget in the Northern Hemisphere, Geophys. Res. Lett. 21, 433–436.Google Scholar
  3. BekkiS., LawK. S., and PyleJ. A.: 1994, Effect of ozone depletion on atmospheric CH4 and CO concentrations, Nature 371, 595–597.Google Scholar
  4. CrutzenP.J. and BrühlC.: 1993, A model study of atmospheric temperatures and the concentration of ozone, hydroxyl, and some other photochemically active gases during the glacial, the preindustrial Holocene and the present, Geophys. Res. Lett. 20, 1047–1050.Google Scholar
  5. CrutzenP. J.: 1995, Ozone in the troposphere, in H. B.Sing (ed.), Composition, Chemistry, and Climate of the Atmosphere, Van Nostrand, New York.Google Scholar
  6. DlugokenckyE. J., MasaireK. A., LangP. M., TansP. P., SteeleL. P., and NisbetE. G.: 1994, A dramatic decrease in the growth rate of atmospheric methane in the Northern Hemisphere during 1992, Geophys. Res. Lett. 21, 45–48.Google Scholar
  7. EbelA., HassH., JakobsH. J., LaubeM., MemmeseheimerM., and OberreuterA.: 1991, Simulation of ozone intrusion caused by a tropopause fold and a cut-off low, Atmos. Environ. 25A, 2131–2144.Google Scholar
  8. FeichterJ. and ZimmermannP. H.: 1989, Cumulus cloud vertical transport studies with the moguntia model, in H.vanDop (ed.), Air Pollution Modeling and its Application VII, Plenum Press, New York, pp. 159–173.Google Scholar
  9. FeisterU. and GreweR.: 1995, Spectral albedo measurements in the UV and visible region over different types of surfaces, Photochem. Photobiol. 62, 736–744.Google Scholar
  10. GranierC., MüllerJ. F., MadronichS., and BrasseurG. P.: 1996, Possible causes for the 1990–1993 decrease in the global tropospheric CO abundances: A three-dimensional sensitivity study, Atmos. Environ. 30, 1673–1682.Google Scholar
  11. FuglestvedtJ. S., JonsonJ. E., and IsaksenI. S. A.: 1994, Effects of reductions in stratospheric ozone on tropospheric chemistry through changes in photolysis rates, Tellus 46B, 172–192.Google Scholar
  12. FuglestvedtJ. S., JonsonJ. E., WangW. C., and IsaksenI. S. A.: 1995, Responses in tropospheric chemistry to changes in UV fluxes, temperatures and water vapour densities, in W. C.Wang and I. S. A.Isaksen (eds), Atmospheric Ozone as a Climatic Gas, NATO ASI series I, Global environmental change vol. 32, Springer-Verlag, Berlin.Google Scholar
  13. HauglandS. O.: 1995, Mid-latitude stratospheric-tropospheric ozone exchange—A trend study, in W. C.Wang and I. S. A.Isaksen (eds), Atmospheric Ozone as a Climate Gas, NATO ASI series I, Global environmental change vol. 32, Springer-Verlag, Berlin.Google Scholar
  14. HoganK. B. and HarrissR. C.: 1994, Comment on ‘A dramatic decrease in the growth rate of atmospheric methane in the Northern Hemisphere during 1992’ by E. J. Dlugokencky et al., Geophys. Res. Lett. 21, 2445–2446.Google Scholar
  15. IPCC: 1990, Climate Change, the IPPC Scientific Assessment, Houghton, J. T., Jenkins, G. H., and Ephraum, J. J. (eds.), Cambridge Univ. Press.Google Scholar
  16. KhalilM. A. K. and RasmussenR. A.: 1994, Carbon monoxide in the Earth's atmosphere: indications of a global increase, Nature, 332, 242–245.Google Scholar
  17. KhalilM. A. K. and RasmussenR. A.: 1994, Global decrease in atmospheric carbon monoxide concentration, Nature, 370, 639–641.Google Scholar
  18. KleinmanL. I.: 1991, Seasonal dependence of boundary layer peroxide concentration: The low and high NOx regimes, J. Geophys. Res. 96, 20721–20733.Google Scholar
  19. LangnerJ., RodheH., and OlofssonM.: 1990, Parametrization of subgrid scale vertical transport in a two-dimensional model of the troposphere, J. Geophys. Res. 95, 13691–13706.Google Scholar
  20. LiuS. C. and TrainerM.: 1988, Responses of tropospheric ozone and odd hydrogen radicals to column ozone changes, J. Atmos. Chem. 6, 221–233.Google Scholar
  21. LiuS. C., McAfeeJ. R., and CiceroneR. J.: 1984, Radon 222 and tropospheric vertical transport, J. Geophys. Res. 89, 7291–7297.Google Scholar
  22. MadronichS. and GranierC.: 1992, Impact of recent total ozone changes on troposheric ozone photodissociation, hydroxyl radicals, and methane trends, Geophys. Res. Lett. 5, 465–467.Google Scholar
  23. MadronichS.: 1987, Implications of recent total atmospheric ozone measurements for biologically active ultraviolet radiation reaching the Earth's surface, Geophys. Res. Lett. 19, 37–40.Google Scholar
  24. MadronichS.: 1993 Tropospheric photochemistry and its response to UV changes, in M.-L.Chanin (ed.), The Role of the Stratosphere in Global Change, NATO ASI Series, I, Vol. 8, Springer-Verlag, Berlin, Heidelberg, pp. 437–461.Google Scholar
  25. Matthijssen, J.: 1995, Modelling of tropospheric ozone and clouds, Thesis, University Utrecht, The Netherlands.Google Scholar
  26. McKeenS. A., KleyD., and VolzA.: 1989, The historical trend of tropospheric ozone over Western Europe: A model perspective, in R. D.Bojkov and P.Fabian (eds), Ozone in the Atmosphere, Proc. 4th quadrennial ozone symposium 1988, Deepak, Hampton (Va), pp. 552–556.Google Scholar
  27. NappoC. J. and vanDopH.: 1994, Simple boundary layer description for global dispersion models, J. Geophys. Res. 99, 10527–10534.Google Scholar
  28. PoppeD., WallaschM., and ZimmermannJ.: 1993, The dependence of the concentration of OH on its precursors under moderately polluted conditions: A model study, J. Atmos. Chem. 16, 61–78.Google Scholar
  29. PratherM. J.: 1994, Lifetime and eigenstates in atmospheric chemistry, Geophys. Res. Lett. 21, 801–804.Google Scholar
  30. PrinnR., CunnoldD., SimmondsP., AlyeaF., BoldiR., CrawfordA., FraserP., GutzlerD., HartleyD., RosenR., and RasmussenR.: 1992, Global average concentration and trend for hydroxyl radicals deduced from ALE/GAGE trichloroethane (methyl chloroform) data for 1978–1990, J. Geophys. Res. 97, 2445–2461.Google Scholar
  31. PrinnR., WeissR. F., MillerB. R., HuangJ., AlyeaF., CunnoldD. M., FraserP. J., HartleyD., and SimmondsP. G.: 1995, Atmospheric trends and lifetime of CH3CCl3 and global OH concentrations, Science 269, 187–192.Google Scholar
  32. RandallD. A. and TjemkesS.: 1991, Clouds, the Earth's radiation budget, and the hydrological cycle, Palaeography, Palaeoclimatogy, Palaeoecology (Global and Planetary Change Section), 90, 3–9, Elsevier, Amsterdam.Google Scholar
  33. RidleyB. A., MadronichS., ChatfieldR. B., WalegaJ. G., ShetterR. E., CarrollM. A., and MontzkaD. D.: 1992, Measurements and model simulations of the photostationary state during The Mauna Loa Observatory Photochemistry Experiment: Implications for radical concentrations and ozone production and loss rates, J. Geophys. Res. 97, 10375–10388.Google Scholar
  34. SillmanS., LoganJ. A., and WofsyS. C.: 1990, The sensitivity of ozone to nitrogen oxides and hydrocarbons in regional ozone episodes, J. Geophys. Res. 95, 1837–1851.Google Scholar
  35. SchaufflerS. M. and DanielJ. S.: 1994. On the effects of stratospheric circulation changes on trace gas trends, J. Geophys. Res. 99, 25747–25754.Google Scholar
  36. ThompsonA. M.: 1992, The oxidizing capacity of the Earth's atmosphere: Probable past and future changes, Science 256, 1157–1165.Google Scholar
  37. TrainerM., BuhrM. P., CurranC. M., FehsenfeldF. C., HsieE. Y., LiuS. C., NortonR. B., ParrishD. D., WilliamsE. J., GandrudB. W., RidleyB. A., ShetterJ. D., AllwineE. J., and WestbergH. H. E.: 1991, Observations and modeling of the reactive nitrogen photochemistry at a rural site, J. Geophys. Res. 85, 7546–7552.Google Scholar
  38. WarneckP.: 1988, Chemistry of the Natural Atmosphere, Int. Geophys. Series 41, Academic Press, San Diego.Google Scholar
  39. WeeleM.van: 1994, A parametrization of the effect of clouds on photodissociation rates; Comparisons with observations, in S.-E.Gryning and M. M.Millan (eds), Proceedings of the 20th ITM on Air Pollution Modelling and its Application, Valencia, Plenum Press, New York, pp. 203–211.Google Scholar
  40. WeeleM.van and DuynkerkeP. G.: 1993, Effects of clouds on the photodissociation of NO2: observations and modelling, J. Atmos. Chem., 16, 231–255.Google Scholar
  41. WMO: 1993, The global energy and water cycle experiment (GEWEX), Bull. World Meteorol. Organ. 42 (1), 20–27.Google Scholar

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • Han Van Dop
    • 1
  • Maarten Krol
    • 1
  1. 1.Institute for Marine and Atmospheric Research (IMAU)Utrecht UniversityUtrechtThe Netherlands

Personalised recommendations