Lower tropospheric ozone at northern midlatitudes: Changing seasonal cycle. Issue 8 (23rd April 2013)

• Record Type: Journal Article
• Authors: Parrish, D. D.; Law, K. S.; Staehelin, J.; Derwent, R.; Cooper, O. R.; Tanimoto, H.; Volz‐Thomas, A.; Gilge, S.; Scheel, H.‐E.; Steinbacher, M.; Chan, E.
• Is Part Of: Geophysical research letters. Volume 40:Issue 8(2013:Apr.)
• Page Start: 1631
• Page End: 1636
• Publication Date: 2013-04-23
• Subjects: ozone -- troposphere -- seasonal cycle -- northern mid‐latitudes; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/grl.50303
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract : [1] At northern midlatitudes the abundance of tropospheric O3 has increased by a factor of approximately 2 since the 1950s. The cause of this increase is generally attributed to increasing anthropogenic precursor emissions, but present chemical and transport models cannot quantitatively reproduce its magnitude. Here we show another manifestation of changes in O3 abundance—a shift of the seasonal cycle at northern midlatitudes so that the observed peak concentrations now appear earlier in the year than in previous decades. The rate of this shift has been 3 to 6 days per decade since the 1970s. We examine possible reasons to explain this shift and suggest it is due to changes in atmospheric transport patterns combined with spatial and temporal changes in emissions. Detailed modeling is necessary to test these hypotheses; this investigation will provide useful guidance for improving global chemistry‐climate models and stringent tests of the model results. Key Points: The date of the maximum of tropospheric ozone has moved to earlier in the year Change has been approximately constant at 3 to 6 days per decade since the 1970s Cause of change may be due to changing climate and/or anthropogenic emissions