Impacts of climate change, ozone recovery, and increasing me

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TitleImpacts of climate change, ozone recovery, and increasing methane on surface ozone and the tropospheric oxidizing capacityAbstractUsing a stratosphere-troposphere chemistry-climate model, we compare the impacts of climate change, stratospheric ozone recovery, and methane increases on surface ozone and the tropospheric oxidizing capacity by 2050. Methane increases lead to a decreasing OH, particularly in the northern subtropics during summer. Stratospheric ozone recovery causes small increases of surface OH driven by increased stratosphere-troposphere exchange, occurring during parts of the year in the southern extratropics. Tropospheric warming is also associated with increasing OH, maximizing in the Northern Hemisphere in northern summer. In combination, OH is anticipated to decrease by approximately 8% in the tropospheric average by 2050 in the scenario considered here. In conjunction with these changes to OH, we model substantial changes in surface ozone in both hemispheres. Methane increases alone will lead to increasing surface ozone by up to 2-3 ppbv in the zonal mean, maximizing around 30N. This increase is exacerbated during austral winter when increased stratosphere-troposphere flux of ozone causes an increase in surface ozone in the southern extratropics. Both increases are partially offset by decreases in surface ozone of up to 2 ppbv in the zonal mean, with substantial zonal asymmetries, due to global warming. We model substantial changes in the methane lifetime caused by the three factors. In the Arctic during summer, disappearing sea ice, in an ice-albedo feedback, causes substantially reduced surface ozone. Of the three factors considered here, methane increases are found to exert the strongest influence on surface ozone. c 2012. American Geophysical Union.AcknowledgementsWe acknowledge the New Zealand Ministry for Business, Innovation, and Employment for funding this work. We acknowledge NCAS Computational Modelling Services for supporting the MetUM. We thank Michael Prather from the University of Irvine for providing the FAST-JX photolysis code. The development of the UKCA model (www.ukca.ac.uk) was supported by the Joint DECC/Defra Hadley Centre Climate Programme (GA01101) and the Natural Environment Research Council (NERC) through the NERC Centres for Atmospheric Science (NCAS) initiative. We acknowledge usage of surface ozone data from the World Data Center for Greenhouse Gases (http://ds.data.jma.go.jp/gmd/wdcgg/index.html).Funding DetailsNERC, Natural Environment Research Council

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1st AuthorMorgenstern, O.AuthorMorgenstern, O.Zeng, G.Abraham, N.Telford, P.Braesicke, P.Pyle, J.Hardiman, S.O'connor, F.Johnson, C.Year2013JournalJournal of Geophysical Research AtmospheresVolume118Number2Pages1028-1041DOI10.1029/2012JD018382URLhttps://www.scopus.com/inward/recor.....df07c450bcd5a4cc0aa8dc6aeKeywordsAtmospheric chemistryAtmosphericsGlobal warmingMethaneOzone layerRecoverySea iceTroposphereUpper atmosphere, Chemistry-climate modelsNorthern HemispheresOxidizing capacityOzone recoveryStratosphere-troposphere exchangeStratospheric ozoneTropospheric warmingZonal asymmetry, Ozone, atmospheric chemistryclimate changeglobal warminghydroxyl radicalmethanenumerical modeloxidationozonetroposphere, rank1

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TypeArticleCitationMorgenstern, O., Zeng, G., Abraham, N., Telford, P., Braesicke, P., Pyle, J., Hardiman, S., O'Connor, F. and Johnson, C. (2013). Impacts of climate change, ozone recovery, and increasing methane on surface ozone and the tropospheric oxidizing capacity. Journal of Geophysical Research Atmospheres, 118(2): 1028-1041 doi:10.1029/2012JD018382 IdentifierMorgenstern2013Relevancerank1