Atmospheric Acetylene and its Relationship with CO as an Indicator of Air Mass Age
View/ Open
Jacob_AtmosphericAcetylene.pdf (1.028Mb)
Access Status
Full text of the requested work is not available in DASH at this time ("restricted access"). For more information on restricted deposits, see our FAQ.Published Version
https://doi.org/10.1029/2006JD008268Metadata
Show full item recordCitation
Xiao, Yaping, Daniel J. Jacob, and Solene Turquety. 2007. Atmospheric acetylene and its relationship with CO as an indicator of air mass age. Journal of Geophysical Research 112: D12305.Abstract
Acetylene (C2H2) and CO originating from combustion are strongly correlated in atmospheric observations, offering constraints on atmospheric dilution and chemical aging. We examine here the C2H2-CO relationships in aircraft observations worldwide, and interpret them with simple models as well as with a global chemical transport model (GEOS-Chem). A C2H2 global source of 6.6 Tg yr−1 in GEOS-Chem simulates the ensemble of global C2H2 observations without systematic bias, and captures most seasonal and regional features. C2H2/CO concentration ratios decrease from continental source regions to the remote atmosphere in a manner consistent between the observations and the model. However, the dC2H2/dCO slope from the linear regression does not show such a systematic decrease, either in the model or in the observations, reflecting variability in background air. The slope β = dlog[C2H2]/dlog[CO] of the linear regression of concentrations in log space offers information for separating the influences of dilution and chemical aging. We find that a linear mixing model with constant dilution rate and background is successful in fresh continental outflow but not in remote air. A diffusion model provides a better conceptual framework for interpreting the observations, where the value of β relative to the square root of the ratio of C2H2 and CO chemical lifetimes (1.7–1.9) measures the relative importance of dilution and chemistry. We thus find that dilution dominates in fresh outflow but chemical loss dominates in remote air. This result is supported by GEOS-Chem sensitivity simulations with modified OH concentrations, and suggests that the model overestimates OH in the southern tropics.Other Sources
http://acmg.seas.harvard.edu/cvdj.htmlCitable link to this page
http://nrs.harvard.edu/urn-3:HUL.InstRepos:4724834
Collections
- FAS Scholarly Articles [18172]
Contact administrator regarding this item (to report mistakes or request changes)