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Isotopic Ordering in Atmospheric O2 as a Tracer of Ozone Photochemistry and the Tropical AtmosphereThe distribution of isotopes within O2 molecules can be rapidly altered when they react with atomic oxygen. This mechanism is globally important: while other contributions to the global budget of O2 impart isotopic signatures, the O(3P) + O2 reaction resets all such signatures in the atmosphere on subdecadal timescales. Consequently, the isotopic distribution within O2 is determined by O3 photochemistry and the circulation patterns that control where that photochemistry occurs. The variability of isotopic ordering in O2 has not been established, however. We present new measurements of 18O18O in air (reported as delta36 values) from the surface to 33 km altitude. They confirm the basic features of the clumped-isotope budget of O2: Stratospheric air has higher delta36 values than tropospheric air (i.e., more 18O18O), reflecting colder temperatures and fast photochemical cycling of O3. Lower delta36 values in the troposphere arise from photochemistry at warmer temperatures balanced by the influx of high-delta36 air from the stratosphere. These observations agree with predictions derived from the GEOS-Chem chemical transport model, which provides additional insight. We find a link between tropical circulation patterns and regions where delta36 values are reset in the troposphere. The dynamics of these regions influences lapse rates, vertical and horizontal patterns of O2 reordering, and thus the isotopic distribution toward which O2 is driven in the troposphere. Temporal variations in delta36 values at the surface should therefore reflect changes in tropospheric temperatures, photochemistry, and circulation. Our results suggest that the tropospheric O3 burden has remained within a +/-10 percent range since 1978.
Document ID
20170001443
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Yeung, Laurence Y.
(William Marsh Rice Univ. Houston, TX, United States)
Murray, Lee T.
(Columbia Univ. Palisades, NY, United States)
Ash, Jeanine L.
(California Univ. Los Angeles, CA, United States)
Young, Edward D.
(California Univ. Los Angeles, CA, United States)
Boering, Kristie A.
(California Univ. Berkeley, CA, United States)
Atlas, Elliot L.
(Miami Univ. Miami, FL, United States)
Schauffler, Sue M.
(National Center for Atmospheric Research Boulder, CO, United States)
Lueb, Richard A.
(National Center for Atmospheric Research Boulder, CO, United States)
Langenfelds, Ray L.
(Commonwealth Scientific and Industrial Research Organization Aspendale, Australia)
Krummel, Paul B.
(Commonwealth Scientific and Industrial Research Organization Aspendale, Australia)
Steele, L. Paul
(Commonwealth Scientific and Industrial Research Organization Aspendale, Australia)
Eastham, Sebastian D.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
February 8, 2017
Publication Date
October 26, 2016
Publication Information
Publication: Journal of Geophysical Research: Atmospheres
Publisher: AGU / Wiley
Volume: 121
Issue: 20
ISSN: 2169-897X
Subject Category
Meteorology And Climatology
Geophysics
Report/Patent Number
GSFC-E-DAA-TN38469
Funding Number(s)
CONTRACT_GRANT: NSF DGE-1144087
CONTRACT_GRANT: NSF EAR-1049655
CONTRACT_GRANT: NNX13AH10G
Distribution Limits
Public
Copyright
Other
Keywords
oxygen
tropical circulation
stratosphere-troposphere exchange
ozone
clumped isotopes
atmospheric residence times

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