@article{fa72370af522447dbfb817dc0b9e4d93,
title = "Carbon monoxide isotopic measurements in Indianapolis constrain urban source isotopic signatures and support mobile fossil fuel emissions as the dominant wintertime CO source",
abstract = " We present measurements of CO mole fraction and CO stable isotopes (δ 13 CO and δC 18 O) in air during the winters of 2013–14 and 2014–15 at tall tower sampling sites in and around Indianapolis, USA. A tower located upwind of the city was used to quantitatively remove the background CO signal, allowing for the first unambiguous isotopic characterization of the urban CO source and yielding 13 CO of –27.7 ± 0.5 VPDB and C 18 O of 17.7 ± 1.1 VSMOW for this source. We use the tower isotope measurements, results from a limited traffic study, as well as atmospheric reaction rates to examine contributions from different sources to the Indianapolis CO budget. Our results are consistent with earlier findings that traffic emissions are the dominant source, suggesting a contribution of 96% or more to the overall Indianapolis wintertime CO emissions. Our results are also consistent with the hypothesis that emissions from a small fraction of vehicles without functional catalytic systems dominate the Indianapolis CO budget.",
keywords = "Carbon Monoxide, Isotopes, Urban",
author = "Vimont, {Isaac J.} and Turnbull, {Jocelyn C.} and Petrenko, {Vasilii V.} and Place, {Philip F.} and Anna Karion and Miles, {Natasha L.} and Richardson, {Scott J.} and Kevin Gurney and Risa Patarasuk and Colm Sweeney and Bruce Vaughn and White, {James W.C.}",
note = "Funding Information: The authors thank the members of the Indianapolis FLUX project, the National Oceanic and Atmospheric Administration{\textquoteright}s Global Monitoring Division Carbon Cycle Greenhouse Gasses Group, the Stable Isotope Laboratory at the University of Colorado, GNS Science, and the National Institute of Standards and Technology for their intellectual, logistical, and financial support. In particular, we are deeply indebted to Paul Shepson of Purdue University for helpful discussions, Thomas Lauvaux for wind, temperature, boundary layer model data, Paul Novelli and his laboratory for his help with CO standard calibration and the CO mole fraction data, and Sylvia Michel for her assistance with database access and IDL support. Funding Information: This research was generously funded by the National Institute of Standards and Technology (grant 60 NANB10D023) and the National Oceanic and Atmospheric Administration Climate Program Office{\textquoteright}s AC4 program (award NA13OAR4310074). The lead author and the analysis system development were supported through funding in conjunction with the INSTAAR contract for isotopic analysis (RA-133R-15-CQ-0044) with The National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory (ESRL) Global Monitoring Division (GMD) Global Greenhouse Gas Reference Network (GGGRN). Publisher Copyright: {\textcopyright} 2017 The Author(s).",
year = "2017",
doi = "10.1525/elementa.136",
language = "English (US)",
volume = "5",
journal = "Elementa",
issn = "2325-1026",
publisher = "BioOne",
}