Activities per year
Abstract
The influence of nitrogen oxides (NOx) on daytime atmospheric oxidation cycles is well known, with clearly defined high- and low-NOx regimes. During the day, oxidation reactions—which contribute to the formation of secondary pollutants such as ozone—are proportional to NOx at low levels, and inversely proportional to NOx at high levels. Night-time oxidation of volatile organic compounds also influences secondary pollutants but lacks a similar clear definition of high- and low-NOx regimes, even though such regimes exist. Decreases in anthropogenic NOx emissions in the US and Europe coincided with increases in Asia over the last 10 to 20 years, and have altered both daytime and nocturnal oxidation cycles. Here we present measurements of chemical species in the lower atmosphere from day- and night-time research flights over the southeast US in 1999 and 2013, supplemented by atmospheric chemistry simulations. We find that night-time oxidation of biogenic volatile organic compounds (BVOC) is NOx-limited when the ratio of NOx to BVOC is below approximately 0.5, and becomes independent of NOx at higher ratios. The night-time ratio of NOx to BVOC in 2013 averaged 0.6 aloft. We suggest that night-time oxidation in the southeast US is in transition between NOx-dominated and ozone-dominated.
Original language | English |
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Pages (from-to) | 490-495 |
Number of pages | 6 |
Journal | Nature Geoscience |
Volume | 10 |
Issue number | 7 |
Early online date | 26 Jun 2017 |
DOIs | |
Publication status | Published - 1 Jul 2017 |
Bibliographical note
© 2017 Macmillan Publishers Limited. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for detailsProfiles
Activities
- 1 Invited talk
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A talk of two parts: NOx control of BVOC oxidation in the SE U.S. and Recent advances in the use of low cost sensors for atmospheric science
Edwards, P. (Chair)
23 Jan 2019Activity: Talk or presentation › Invited talk