Chemical analysis of the Asian tropopause aerosol layer (ATAL) with emphasis on secondary aerosol particles using aircraft-based in situ aerosol mass spectrometry
<p>Aircraft-borne in situ measurements of the chemical aerosol composition were conducted in the Asian tropopause aerosol layer (ATAL) over the Indian subcontinent in the summer of 2017, covering particle sizes below <span class="inline-formula">∼3</span> <span class=&...
| Main Authors: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-10-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/13607/2022/acp-22-13607-2022.pdf |
| _version_ | 1811340100523524096 |
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| author | O. Appel O. Appel F. Köllner A. Dragoneas A. Dragoneas A. Hünig A. Hünig S. Molleker H. Schlager C. Mahnke C. Mahnke R. Weigel M. Port M. Port C. Schulz C. Schulz F. Drewnick B. Vogel F. Stroh S. Borrmann S. Borrmann |
| author_facet | O. Appel O. Appel F. Köllner A. Dragoneas A. Dragoneas A. Hünig A. Hünig S. Molleker H. Schlager C. Mahnke C. Mahnke R. Weigel M. Port M. Port C. Schulz C. Schulz F. Drewnick B. Vogel F. Stroh S. Borrmann S. Borrmann |
| author_sort | O. Appel |
| collection | DOAJ |
| description | <p>Aircraft-borne in situ measurements of the chemical aerosol
composition were conducted in the Asian tropopause aerosol layer
(ATAL) over the Indian subcontinent in the summer of 2017, covering particle sizes below <span class="inline-formula">∼3</span> <span class="inline-formula">µm</span>. We have implemented a recently
developed aerosol mass spectrometer, which adopts the laser desorption technique as well as the thermal desorption method for quantitative
bulk information (i.e., a modified Aerodyne AMS), aboard the
high-altitude research aircraft M-55 <i>Geophysica</i>. The
instrument was deployed in July and August 2017 during the
StratoClim EU campaign (Stratospheric and upper tropospheric
processes for better Climate predictions) over Nepal, India,
Bangladesh, and the Bay of Bengal, covering altitudes up to
20 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">km</mi><mspace linebreak="nobreak" width="0.125em"/><mi mathvariant="normal">a</mi><mo>.</mo><mi mathvariant="normal">s</mi><mo>.</mo><mi mathvariant="normal">l</mi><mo>.</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="1131ba4fc5d7a8797866fa65a0408576"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-13607-2022-ie00001.svg" width="41pt" height="10pt" src="acp-22-13607-2022-ie00001.png"/></svg:svg></span></span> For particles with diameters between
10 <span class="inline-formula">nm</span> and <span class="inline-formula">∼3</span> <span class="inline-formula">µm</span>, the vertical profiles of
aerosol number densities from the eight research flights show
significant enhancements in the altitude range of the ATAL. We
observed enhancements in the mass concentrations of particulate
nitrate, ammonium, and organics in a similar altitude range between
approximately 13 and 18 <span class="inline-formula">km</span> (corresponding to
360 and 410 <span class="inline-formula">K</span> potential temperature). By means of
the two aerosol mass spectrometry techniques, we show that the
particles in the ATAL mainly consist of ammonium nitrate (AN) and
organics. The single-particle analysis from laser desorption and
ionization mass spectrometry revealed that a significant particle
fraction (up to 70 % of all analyzed particles by number) within
the ATAL results from the conversion of inorganic and organic gas-phase
precursors, rather than from the uplift of primary particles from
below. This can be inferred from the fact that the majority of the
particles encountered in the ATAL consisted solely of secondary
substances, namely an internal mixture of nitrate, ammonium, sulfate,
and organic matter. These particles are externally mixed with
particles containing primary components as well. The single-particle
analysis suggests that the organic matter within the ATAL and in the
lower stratosphere (even above 420 <span class="inline-formula">K</span>) can partly be identified
as organosulfates (OS), in particular glycolic acid sulfate, which are
known as components indicative for secondary organic aerosol (SOA)
formation. Additionally, the secondary particles are smaller in size compared to those containing primary components (mainly potassium, metals, and elemental carbon). The analysis of particulate organics with the
thermal desorption method shows that the degree of oxidation for
particles observed in the ATAL is consistent with expectations about
secondary organics that were subject to photochemical processing and
aging. We found that organic aerosol was less oxidized in lower
regions of the ATAL (<span class="inline-formula"><380</span> <span class="inline-formula">K</span>) compared to higher altitudes
(here 390–420 <span class="inline-formula">K</span>). These results suggest that particles formed
in the lower ATAL are uplifted by prevailing diabatic heating
processes and thereby subject to extensive oxidative aging. Thus, our
observations are consistent with the concept of precursor gases being
emitted from regional ground sources, subjected to rapid convective
uplift, and followed by secondary particle formation and growth in the
upper troposphere within the confinement of the Asian monsoon
anticyclone (AMA). As a consequence, the chemical composition of these
particles largely differs from the aerosol in the lower stratospheric
background and the Junge layer.</p> |
| first_indexed | 2024-04-13T18:37:23Z |
| format | Article |
| id | doaj.art-bce3a050353e424d937e130ac7ea0d92 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-13T18:37:23Z |
| publishDate | 2022-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-bce3a050353e424d937e130ac7ea0d922022-12-22T02:34:51ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242022-10-0122136071363010.5194/acp-22-13607-2022Chemical analysis of the Asian tropopause aerosol layer (ATAL) with emphasis on secondary aerosol particles using aircraft-based in situ aerosol mass spectrometryO. Appel0O. Appel1F. Köllner2A. Dragoneas3A. Dragoneas4A. Hünig5A. Hünig6S. Molleker7H. Schlager8C. Mahnke9C. Mahnke10R. Weigel11M. Port12M. Port13C. Schulz14C. Schulz15F. Drewnick16B. Vogel17F. Stroh18S. Borrmann19S. Borrmann20Max Planck Institute for Chemistry, Mainz, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University, Mainz, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University, Mainz, GermanyMax Planck Institute for Chemistry, Mainz, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University, Mainz, GermanyMax Planck Institute for Chemistry, Mainz, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University, Mainz, GermanyMax Planck Institute for Chemistry, Mainz, GermanyDeutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, GermanyMax Planck Institute for Chemistry, Mainz, Germanynow at: Institute of Energy and Climate Research (IEK-8), Forschungszentrum Jülich GmbH, Jülich, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University, Mainz, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University, Mainz, Germanynow at: Montessori Zentrum Hofheim, GermanyMax Planck Institute for Chemistry, Mainz, Germanynow at: Leibniz-Zentrum für Agrarlandschaftsforschung, Müncheberg, GermanyMax Planck Institute for Chemistry, Mainz, GermanyInstitute of Energy and Climate Research (IEK-7), Forschungszentrum Jülich, Jülich, GermanyInstitute of Energy and Climate Research (IEK-7), Forschungszentrum Jülich, Jülich, GermanyMax Planck Institute for Chemistry, Mainz, GermanyInstitute for Atmospheric Physics, Johannes Gutenberg University, Mainz, Germany<p>Aircraft-borne in situ measurements of the chemical aerosol composition were conducted in the Asian tropopause aerosol layer (ATAL) over the Indian subcontinent in the summer of 2017, covering particle sizes below <span class="inline-formula">∼3</span> <span class="inline-formula">µm</span>. We have implemented a recently developed aerosol mass spectrometer, which adopts the laser desorption technique as well as the thermal desorption method for quantitative bulk information (i.e., a modified Aerodyne AMS), aboard the high-altitude research aircraft M-55 <i>Geophysica</i>. The instrument was deployed in July and August 2017 during the StratoClim EU campaign (Stratospheric and upper tropospheric processes for better Climate predictions) over Nepal, India, Bangladesh, and the Bay of Bengal, covering altitudes up to 20 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">km</mi><mspace linebreak="nobreak" width="0.125em"/><mi mathvariant="normal">a</mi><mo>.</mo><mi mathvariant="normal">s</mi><mo>.</mo><mi mathvariant="normal">l</mi><mo>.</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="1131ba4fc5d7a8797866fa65a0408576"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-13607-2022-ie00001.svg" width="41pt" height="10pt" src="acp-22-13607-2022-ie00001.png"/></svg:svg></span></span> For particles with diameters between 10 <span class="inline-formula">nm</span> and <span class="inline-formula">∼3</span> <span class="inline-formula">µm</span>, the vertical profiles of aerosol number densities from the eight research flights show significant enhancements in the altitude range of the ATAL. We observed enhancements in the mass concentrations of particulate nitrate, ammonium, and organics in a similar altitude range between approximately 13 and 18 <span class="inline-formula">km</span> (corresponding to 360 and 410 <span class="inline-formula">K</span> potential temperature). By means of the two aerosol mass spectrometry techniques, we show that the particles in the ATAL mainly consist of ammonium nitrate (AN) and organics. The single-particle analysis from laser desorption and ionization mass spectrometry revealed that a significant particle fraction (up to 70 % of all analyzed particles by number) within the ATAL results from the conversion of inorganic and organic gas-phase precursors, rather than from the uplift of primary particles from below. This can be inferred from the fact that the majority of the particles encountered in the ATAL consisted solely of secondary substances, namely an internal mixture of nitrate, ammonium, sulfate, and organic matter. These particles are externally mixed with particles containing primary components as well. The single-particle analysis suggests that the organic matter within the ATAL and in the lower stratosphere (even above 420 <span class="inline-formula">K</span>) can partly be identified as organosulfates (OS), in particular glycolic acid sulfate, which are known as components indicative for secondary organic aerosol (SOA) formation. Additionally, the secondary particles are smaller in size compared to those containing primary components (mainly potassium, metals, and elemental carbon). The analysis of particulate organics with the thermal desorption method shows that the degree of oxidation for particles observed in the ATAL is consistent with expectations about secondary organics that were subject to photochemical processing and aging. We found that organic aerosol was less oxidized in lower regions of the ATAL (<span class="inline-formula"><380</span> <span class="inline-formula">K</span>) compared to higher altitudes (here 390–420 <span class="inline-formula">K</span>). These results suggest that particles formed in the lower ATAL are uplifted by prevailing diabatic heating processes and thereby subject to extensive oxidative aging. Thus, our observations are consistent with the concept of precursor gases being emitted from regional ground sources, subjected to rapid convective uplift, and followed by secondary particle formation and growth in the upper troposphere within the confinement of the Asian monsoon anticyclone (AMA). As a consequence, the chemical composition of these particles largely differs from the aerosol in the lower stratospheric background and the Junge layer.</p>https://acp.copernicus.org/articles/22/13607/2022/acp-22-13607-2022.pdf |
| spellingShingle | O. Appel O. Appel F. Köllner A. Dragoneas A. Dragoneas A. Hünig A. Hünig S. Molleker H. Schlager C. Mahnke C. Mahnke R. Weigel M. Port M. Port C. Schulz C. Schulz F. Drewnick B. Vogel F. Stroh S. Borrmann S. Borrmann Chemical analysis of the Asian tropopause aerosol layer (ATAL) with emphasis on secondary aerosol particles using aircraft-based in situ aerosol mass spectrometry Atmospheric Chemistry and Physics |
| title | Chemical analysis of the Asian tropopause aerosol layer (ATAL) with emphasis on secondary aerosol particles using aircraft-based in situ aerosol mass spectrometry |
| title_full | Chemical analysis of the Asian tropopause aerosol layer (ATAL) with emphasis on secondary aerosol particles using aircraft-based in situ aerosol mass spectrometry |
| title_fullStr | Chemical analysis of the Asian tropopause aerosol layer (ATAL) with emphasis on secondary aerosol particles using aircraft-based in situ aerosol mass spectrometry |
| title_full_unstemmed | Chemical analysis of the Asian tropopause aerosol layer (ATAL) with emphasis on secondary aerosol particles using aircraft-based in situ aerosol mass spectrometry |
| title_short | Chemical analysis of the Asian tropopause aerosol layer (ATAL) with emphasis on secondary aerosol particles using aircraft-based in situ aerosol mass spectrometry |
| title_sort | chemical analysis of the asian tropopause aerosol layer atal with emphasis on secondary aerosol particles using aircraft based in situ aerosol mass spectrometry |
| url | https://acp.copernicus.org/articles/22/13607/2022/acp-22-13607-2022.pdf |
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