Measurements of CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> in the upper troposphere
Methyl peroxy nitrate (CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub>) is a non-acyl peroxy nitrate that is important for photochemistry at low temperatures characteristic of the upper troposphere. We report the first measurements of CH<sub>3</sub>O<sub&...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-02-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/8/987/2015/amt-8-987-2015.pdf |
| Summary: | Methyl peroxy nitrate (CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub>) is a non-acyl peroxy nitrate
that is important for photochemistry at low temperatures characteristic of
the upper troposphere. We report the first measurements of
CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub>, which we achieved through a new aircraft inlet
configuration, combined with thermal-dissociation laser-induced fluorescence
(TD-LIF) detection of NO<sub>2</sub>, and describe the accuracy, specificity, and
interferences to CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> measurements.
CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> is predicted to be a ubiquitous interference to
upper-tropospheric NO<sub>2</sub> measurements. We describe an experimental
strategy for obtaining NO<sub>2</sub> observations free of the
CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> interference. Using these new methods, we made
observations during two recent aircraft campaigns: the Deep Convective
Clouds and Chemistry (DC-3) and the Studies of Emissions and Atmospheric
Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS)
experiments. The CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> measurements we report have a
detection limit (<i>S/N</i> = 2) of 15 pptv at 1 min averaging on a background
of 200 pptv NO<sub>2</sub> and an accuracy of ±40%. Observations are
used to constrain the interference of pernitric acid (HO<sub>2</sub>NO<sub>2</sub>) to
the CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> measurements, as HO<sub>2</sub>NO<sub>2</sub> partially
decomposes (~11%) along with CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> in
the heated CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> channel used to detect
CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub>. |
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| ISSN: | 1867-1381 1867-8548 |