Missing OH reactivity in the global marine boundary layer
<p>The hydroxyl radical (OH) reacts with thousands of chemical species in the atmosphere, initiating their removal and the chemical reaction sequences that produce ozone, secondary aerosols, and gas-phase acids. OH reactivity, which is the inverse of OH lifetime, influences the OH abundance an...
Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2020-04-01
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Series: | Atmospheric Chemistry and Physics |
Online Access: | https://www.atmos-chem-phys.net/20/4013/2020/acp-20-4013-2020.pdf |
Summary: | <p>The hydroxyl radical (OH) reacts with thousands of
chemical species in the atmosphere, initiating their removal and the
chemical reaction sequences that produce ozone, secondary aerosols, and
gas-phase acids. OH reactivity, which is the inverse of OH lifetime,
influences the OH abundance and the ability of OH to cleanse the atmosphere.
The NASA Atmospheric Tomography (ATom) campaign used instruments on the NASA
DC-8 aircraft to measure OH reactivity and more than 100 trace chemical
species. ATom presented a unique opportunity to test the completeness of the
OH reactivity calculated from the chemical species measurements by comparing
it to the measured OH reactivity over two oceans across four seasons.
Although the calculated OH reactivity was below the limit of detection for
the ATom instrument used to measure OH reactivity throughout much of the
free troposphere, the instrument was able to measure the OH reactivity in
and just above the marine boundary layer. The mean measured value of OH
reactivity in the marine boundary layer across all latitudes and all ATom
deployments was 1.9 s<span class="inline-formula"><sup>−1</sup></span>, which is 0.5 s<span class="inline-formula"><sup>−1</sup></span> larger than the mean
calculated OH reactivity. The missing OH reactivity, the difference between
the measured and calculated OH reactivity, varied between 0 and 3.5 s<span class="inline-formula"><sup>−1</sup></span>, with the highest values over the Northern Hemisphere Pacific
Ocean. Correlations of missing OH reactivity with formaldehyde, dimethyl
sulfide, butanal, and sea surface temperature<span id="page4014"/> suggest the presence of
unmeasured or unknown volatile organic compounds or oxygenated volatile
organic compounds associated with ocean emissions.</p> |
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ISSN: | 1680-7316 1680-7324 |