Mass spectrometric measurements of ambient ions and estimation of gaseous sulfuric acid in the free troposphere and lowermost stratosphere during the CAFE-EU/BLUESKY campaign
<p>Ambient ions play an important role in atmospheric processes such as ion-induced new particle formation. While there are several studies of ambient ions for different layers of the atmosphere, data coverage for the free troposphere and especially the upper troposphere and lower stratosphere...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-09-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/11781/2022/acp-22-11781-2022.pdf |
| Summary: | <p>Ambient ions play an important role in atmospheric
processes such as ion-induced new particle formation. While there are
several studies of ambient ions for different layers of the atmosphere, data
coverage for the free troposphere and especially the upper troposphere and
lower stratosphere (UTLS) region is scarce. Here, we present the first
airborne measurements of ambient ions using a high-resolution atmospheric
pressure interface time-of-flight mass spectrometer (HR-APi-TOF-MS) in the
free troposphere and lower stratosphere above Europe on board the HALO
aircraft during the CAFE-EU/BLUESKY campaign in May and June 2020. In
negative measurement mode, we observed nitrate and hydrogen sulfate and
their related ion clusters in an altitude range of 4.7 to 13.4 km. The
horizontal profiles for those ions reveal an increasing count rate for
NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="5c4cefaf8b78d41c1ce2f2ef151f712f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-11781-2022-ie00001.svg" width="9pt" height="16pt" src="acp-22-11781-2022-ie00001.png"/></svg:svg></span></span> and (HNO<span class="inline-formula"><sub>3</sub>)</span>NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="0aaab3ee324d7a9ba8e4b96f67d8036e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-11781-2022-ie00002.svg" width="9pt" height="16pt" src="acp-22-11781-2022-ie00002.png"/></svg:svg></span></span> towards higher altitudes but
no significant trend for HSO4<span class="inline-formula"><sup>−</sup></span>. From the count rates of the nitrate
(NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="8c72af1edd6d67ed562efcaf5163d22b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-11781-2022-ie00003.svg" width="9pt" height="16pt" src="acp-22-11781-2022-ie00003.png"/></svg:svg></span></span>) and hydrogen sulfate (HSO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="339da67f118260d512683cde4508e1ea"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-11781-2022-ie00004.svg" width="9pt" height="16pt" src="acp-22-11781-2022-ie00004.png"/></svg:svg></span></span>) core ions, we
inferred the number concentration of gaseous sulfuric acid. The lowest
average value was found to be <span class="inline-formula">1.9×10<sup>5</sup></span> cm<span class="inline-formula"><sup>−3</sup></span> at the
maximum altitude bin, i.e. 13.4 km. The highest average value of
<span class="inline-formula">7.8×10<sup>5</sup></span> cm<span class="inline-formula"><sup>−3</sup></span> was observed in the 8.7–9.2 km altitude
bin. During the transit through a mixed-phase cloud, we observed an event of
enhanced ion count rates and aerosol particle concentrations that can
largely be assigned to nitrate ions and particles, respectively; this may
have been caused by the shattering of liquid cloud droplets on the surface
of the aircraft or the inlet. Furthermore, we report the proof of principle
for the measurement of ambient cations and the identification of protonated
pyridine.</p> |
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| ISSN: | 1680-7316 1680-7324 |