Measurement of ambient NO<sub>3</sub> reactivity: design, characterization and first deployment of a new instrument
We describe the first instrument for measurement of the rate constant (s<sup>−1</sup>) for reactive loss (i.e., the total reactivity) of NO<sub>3</sub> in ambient air. Cavity-ring-down spectroscopy is used to monitor the mixing ratio of synthetically generated NO<sub>3&...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2017-03-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/10/1241/2017/amt-10-1241-2017.pdf |
| _version_ | 1818487767628251136 |
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| author | J. M. Liebmann G. Schuster J. B. Schuladen N. Sobanski J. Lelieveld J. N. Crowley |
| author_facet | J. M. Liebmann G. Schuster J. B. Schuladen N. Sobanski J. Lelieveld J. N. Crowley |
| author_sort | J. M. Liebmann |
| collection | DOAJ |
| description | We describe the first instrument for measurement of the
rate constant (s<sup>−1</sup>) for reactive loss (i.e., the total reactivity) of
NO<sub>3</sub> in ambient air. Cavity-ring-down spectroscopy is used to monitor
the mixing ratio of synthetically generated NO<sub>3</sub> ( ≈ 30–50 pptv)
after passing through a flow-tube reactor with variable residence time
(generally 10.5 s). The change in concentration of NO<sub>3</sub> upon modulation
of the bath gas between zero air and ambient air is used to derive its loss
rate constant, which is then corrected for formation and decomposition of
N<sub>2</sub>O<sub>5</sub> via numerical simulation. The instrument is calibrated and
characterized using known amounts of NO and NO<sub>2</sub> and tested in the
laboratory with an isoprene standard. The lowest reactivity that can be
detected (defined by the stability of the NO<sub>3</sub> source, instrumental
parameters and NO<sub>2</sub> mixing ratios) is 0.005 s<sup>−1</sup>. An automated
dilution procedure enables measurement of NO<sub>3</sub> reactivities up to 45 s<sup>−1</sup>, this upper limit being defined mainly by the dilution accuracy.
The typical total uncertainty associated with the reactivity measurement at
the center of its dynamic range is 16 %, though this is dependent on
ambient NO<sub>2</sub> levels. Results from the first successful deployment of the
instrument at a forested mountain site with urban influence are shown and
future developments outlined. |
| first_indexed | 2024-12-10T16:42:18Z |
| format | Article |
| id | doaj.art-bdeca72b77ff422489d40ff312516167 |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-12-10T16:42:18Z |
| publishDate | 2017-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-bdeca72b77ff422489d40ff3125161672022-12-22T01:41:11ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482017-03-011031241125810.5194/amt-10-1241-2017Measurement of ambient NO<sub>3</sub> reactivity: design, characterization and first deployment of a new instrumentJ. M. Liebmann0G. Schuster1J. B. Schuladen2N. Sobanski3J. Lelieveld4J. N. Crowley5Atmospheric Chemistry Department, Max-Planck-Institut für Chemie, 55128 Mainz, GermanyAtmospheric Chemistry Department, Max-Planck-Institut für Chemie, 55128 Mainz, GermanyAtmospheric Chemistry Department, Max-Planck-Institut für Chemie, 55128 Mainz, GermanyAtmospheric Chemistry Department, Max-Planck-Institut für Chemie, 55128 Mainz, GermanyAtmospheric Chemistry Department, Max-Planck-Institut für Chemie, 55128 Mainz, GermanyAtmospheric Chemistry Department, Max-Planck-Institut für Chemie, 55128 Mainz, GermanyWe describe the first instrument for measurement of the rate constant (s<sup>−1</sup>) for reactive loss (i.e., the total reactivity) of NO<sub>3</sub> in ambient air. Cavity-ring-down spectroscopy is used to monitor the mixing ratio of synthetically generated NO<sub>3</sub> ( ≈ 30–50 pptv) after passing through a flow-tube reactor with variable residence time (generally 10.5 s). The change in concentration of NO<sub>3</sub> upon modulation of the bath gas between zero air and ambient air is used to derive its loss rate constant, which is then corrected for formation and decomposition of N<sub>2</sub>O<sub>5</sub> via numerical simulation. The instrument is calibrated and characterized using known amounts of NO and NO<sub>2</sub> and tested in the laboratory with an isoprene standard. The lowest reactivity that can be detected (defined by the stability of the NO<sub>3</sub> source, instrumental parameters and NO<sub>2</sub> mixing ratios) is 0.005 s<sup>−1</sup>. An automated dilution procedure enables measurement of NO<sub>3</sub> reactivities up to 45 s<sup>−1</sup>, this upper limit being defined mainly by the dilution accuracy. The typical total uncertainty associated with the reactivity measurement at the center of its dynamic range is 16 %, though this is dependent on ambient NO<sub>2</sub> levels. Results from the first successful deployment of the instrument at a forested mountain site with urban influence are shown and future developments outlined.http://www.atmos-meas-tech.net/10/1241/2017/amt-10-1241-2017.pdf |
| spellingShingle | J. M. Liebmann G. Schuster J. B. Schuladen N. Sobanski J. Lelieveld J. N. Crowley Measurement of ambient NO<sub>3</sub> reactivity: design, characterization and first deployment of a new instrument Atmospheric Measurement Techniques |
| title | Measurement of ambient NO<sub>3</sub> reactivity: design, characterization and first deployment of a new instrument |
| title_full | Measurement of ambient NO<sub>3</sub> reactivity: design, characterization and first deployment of a new instrument |
| title_fullStr | Measurement of ambient NO<sub>3</sub> reactivity: design, characterization and first deployment of a new instrument |
| title_full_unstemmed | Measurement of ambient NO<sub>3</sub> reactivity: design, characterization and first deployment of a new instrument |
| title_short | Measurement of ambient NO<sub>3</sub> reactivity: design, characterization and first deployment of a new instrument |
| title_sort | measurement of ambient no sub 3 sub reactivity design characterization and first deployment of a new instrument |
| url | http://www.atmos-meas-tech.net/10/1241/2017/amt-10-1241-2017.pdf |
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