Profiling of formaldehyde, glyoxal, methylglyoxal, and CO over the Amazon

• Verfasst von: Kluge, Flora [VerfasserIn]
• Verfasst von: Hüneke, Tilman [VerfasserIn]
• Verfasst von: Knecht, Matthias [VerfasserIn]
• Verfasst von: Lichtenstern, Michael [VerfasserIn]
• Verfasst von: Rotermund, Meike [VerfasserIn]
• Verfasst von: Schlager, Hans [VerfasserIn]
• Verfasst von: Weyland, Benjamin [VerfasserIn]
• Verfasst von: Pfeilsticker, Klaus [VerfasserIn]
• Titel: Profiling of formaldehyde, glyoxal, methylglyoxal, and CO over the Amazon
• Titelzusatz: normalized excess mixing ratios and related emission factors in biomass burning plumes
• Verf.angabe: Flora Kluge, Tilman Hüneke, Matthias Knecht, Michael Lichtenstern, Meike Rotermund, Hans Schlager, Benjamin Schreiner, Klaus Pfeilsticker
• E-Jahr: 2020
• Jahr: 29 Oct 2020
• Umfang: 27 S.
• Fussnoten: Gesehen am 24.11.2020
• Titel Quelle: Enthalten in: Atmospheric chemistry and physics
• Ort Quelle: Katlenburg-Lindau : EGU, 2001
• Jahr Quelle: 2020
• Band/Heft Quelle: 20(2020), 20, Seite 12363-12389
• ISSN Quelle: 1680-7324
• DOI: doi:10.5194/acp-20-12363-2020
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1740812301

Abstract

Abstract. We report on airborne measurements of tropospheric mixing ratios and vertical profiles of formaldehyde (<span class="inline-formula">CH₂O</span>), glyoxal (<span class="inline-formula">C₂H₂O₂</span>), methylglyoxal and higher carbonyls (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mn mathvariant="normal">3</mn></msub><msub><mi mathvariant="normal">H</mi><mn mathvariant="normal">4</mn></msub><msubsup><mi mathvariant="normal">O</mi><mn mathvariant="normal">2</mn><mo>*</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="af988864cbcdcafdc3df86b6a358936b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-12363-2020-ie00001.svg" width="41pt" height="14pt" src="acp-20-12363-2020-ie00001.png"/></svg:svg></span></span>) (see below), and carbon monoxide (<span class="inline-formula">CO</span>) over the Amazon Basin during the ACRIDICON-CHUVA campaign from the German High Altitude and Long-range research aircraft (HALO) in autumn 2014. The joint observation of in situ <span class="inline-formula">CO</span> and remotely measured <span class="inline-formula">CH₂O</span>, <span class="inline-formula">C₂H₂O₂</span>, and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mn mathvariant="normal">3</mn></msub><msub><mi mathvariant="normal">H</mi><mn mathvariant="normal">4</mn></msub><msubsup><mi mathvariant="normal">O</mi><mn mathvariant="normal">2</mn><mo>*</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="ef1d34cc9d4b75383356dfc5a6d1cdf1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-12363-2020-ie00002.svg" width="41pt" height="14pt" src="acp-20-12363-2020-ie00002.png"/></svg:svg></span></span>, together with visible imagery and air mass back-trajectory modelling using NOAA HYSPLIT (National Oceanic Atmospheric Administration, HYbrid Single-Particle Lagrangian Integrated Trajectory), allows us to discriminate between the probing of background tropical air, in which the concentration of the measured species results from the oxidation of biogenically emitted volatile organic compounds (VOCs, mostly isoprene), and measurements of moderately to strongly polluted air masses affected by biomass burning emissions or the city plume of Manaus. For 12 near-surface measurements of fresh biomass burning plumes, normalized excess mixing ratios of <span class="inline-formula">C₂H₂O₂</span> and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mn mathvariant="normal">3</mn></msub><msub><mi mathvariant="normal">H</mi><mn mathvariant="normal">4</mn></msub><msubsup><mi mathvariant="normal">O</mi><mn mathvariant="normal">2</mn><mo>*</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="2ed961b4f0644d9e3f0f6f3d6a5f4cd1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-12363-2020-ie00003.svg" width="41pt" height="14pt" src="acp-20-12363-2020-ie00003.png"/></svg:svg></span></span> with respect to <span class="inline-formula">CH₂O</span> are inferred and compared to recent studies. The mean glyoxal-to-formaldehyde ratio <span class="inline-formula"><i>R</i>_GF=0.07</span> (range 0.02-0.11) is in good agreement with recent reports which suggest <span class="inline-formula"><i>R</i>_GF</span> to be significantly lower than previously assumed in global chemical transport models (CTMs). The mean methylglyoxal-to-formaldehyde ratio <span class="inline-formula"><i>R</i>_MF=0.98</span> (range 0.09-1.50) varies significantly during the different observational settings but overall appears to be much larger (up to a factor of 5) than previous reports suggest even when applying a correction factor of <span class="inline-formula">2.0±0.5</span> to account for the additional dicarbonyls included in the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M16" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mn mathvariant="normal">3</mn></msub><msub><mi mathvariant="normal">H</mi><mn mathvariant="normal">4</mn></msub><msubsup><mi mathvariant="normal">O</mi><mn mathvariant="normal">2</mn><mo>*</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="49b151acafa38023d601c2a77f7be38e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-12363-2020-ie00004.svg" width="41pt" height="14pt" src="acp-20-12363-2020-ie00004.png"/></svg:svg></span></span> measurements. Using recently reported emission factors of <span class="inline-formula">CH₂O</span> for tropical forests, our observations suggest emission factors of <span class="inline-formula">EF_G=0.25</span> (range 0.11 to 0.52) <span class="inline-formula">g kg⁻¹</span> for <span class="inline-formula">C₂H₂O₂</span> and <span class="inline-formula">EF_M</span> = 4.7 (range 0.5 to 8.64) <span class="inline-formula">g kg⁻¹</span> for <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mn mathvariant="normal">3</mn></msub><msub><mi mathvariant="normal">H</mi><mn mathvariant="normal">4</mn></msub><msubsup><mi mathvariant="normal">O</mi><mn mathvariant="normal">2</mn><mo>*</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="9b23584d462cefbaaa486b5b3c5dfaa8"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-20-12363-2020-ie00005.svg" width="41pt" height="14pt" src="acp-20-12363-2020-ie00005.png"/></svg:svg></span></span>. While <span class="inline-formula">EF_G</span> agrees well with recent reports, <span class="inline-formula">EF_M</span> is (like <span class="inline-formula"><i>R</i>_MF</span>) slightly larger than reported in other studies, presumably due to the different plume ages or fuels studied. Our observations of these critical carbonyls and intermediate oxidation products may support future photochemical modelling of air pollution over tropical vegetation, as well as validate past and present space-borne observations of the respective species.</p>