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A Born‐Oppenheimer photolysis model of N 2 O fractionation
Author(s) -
Blake Geoffrey A.,
Liang MaoChang,
Morgan Christopher G.,
Yung Yuk L.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl016932
Subject(s) - photodissociation , fractionation , nitrous oxide , stratosphere , anomaly (physics) , atmospheric chemistry , atmospheric sciences , environmental science , chemistry , physics , meteorology , photochemistry , ozone , organic chemistry , condensed matter physics
The isotopically light N 2 O produced by microbial activity is thought to be balanced by the return of heavy stratospheric nitrous oxide. The Yung and Miller [1997] method that first explained these trends yields photolytic fractionation factors ∼half those observed by experiment or predicted quantum mechanically, however. To address these issues, we present here a Born‐Oppenheimer photolysis model that uses only commonly available spectroscopic data. The predicted fractionations quantitatively reproduce laboratory data, and have been incorporated into zonally averaged atmospheric simulations. Like McLinden et al. [2003], who employ a three‐dimensional chemical transport model with cross sections scaled to match laboratory data, we find excellent agreement between predictions and stratospheric measurements; additional processes that contribute to the mass independent anomaly in N 2 O can only account for a fraction of its global budget.