Summer aerosol measurements over the East Antarctic seasonal ice zone
Aerosol measurements over the Southern Ocean have been identified as critical to an improved understanding of aerosol–radiation and aerosol–cloud interactions, as there currently exists significant discrepancies between model results and measurements in this region. The atmosphere above the Southern...
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Online Access: | https://doi.org/10.5194/acp-21-9497-2021 https://acp.copernicus.org/articles/21/9497/2021/ |
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ftcopernicus:oai:publications.copernicus.org:acp91413 2023-05-15T14:02:17+02:00 Summer aerosol measurements over the East Antarctic seasonal ice zone Simmons, Jack B. Humphries, Ruhi S. Wilson, Stephen R. Chambers, Scott D. Williams, Alastair G. Griffiths, Alan D. McRobert, Ian M. Ward, Jason P. Keywood, Melita D. Gribben, Sean 2021-06-23 application/pdf https://doi.org/10.5194/acp-21-9497-2021 https://acp.copernicus.org/articles/21/9497/2021/ eng eng doi:10.5194/acp-21-9497-2021 https://acp.copernicus.org/articles/21/9497/2021/ eISSN: 1680-7324 Text 2021 ftcopernicus https://doi.org/10.5194/acp-21-9497-2021 2021-06-28T16:22:14Z Aerosol measurements over the Southern Ocean have been identified as critical to an improved understanding of aerosol–radiation and aerosol–cloud interactions, as there currently exists significant discrepancies between model results and measurements in this region. The atmosphere above the Southern Ocean provides crucial insight into an aerosol regime relatively free from anthropogenic influence, yet its remoteness ensures atmospheric measurements are relatively rare. Here we present observations from the Polar Cell Aerosol Nucleation (PCAN) campaign, hosted aboard the RV Investigator during a summer (January–March) 2017 voyage from Hobart, Australia, to the East Antarctic seasonal sea ice zone. A median particle number concentration (condensation nuclei > 3 nm; CN 3 ) of 354 (95 % CI 345–363) cm −3 was observed from the voyage. Median cloud condensation nuclei (CCN) concentrations were 167 (95 % CI 158–176) cm −3 . Measured particle size distributions suggested that aerosol populations had undergone significant cloud processing. To understand the variability in aerosol observations, measurements were classified by meteorological variables. Wind direction and absolute humidity were used to identify different air masses, and aerosol measurements were compared based on these identifications. CN 3 concentrations measured during SE wind directions (median 594 cm −3 ) were higher than those measured during wind directions from the NW (median 265 cm −3 ). Increased frequency of measurements from these wind directions suggests the influence of large-scale atmospheric transport mechanisms on the local aerosol population in the boundary layer of the East Antarctic seasonal ice zone. Modelled back trajectories imply different air mass histories for each measurement group, supporting this suggestion. CN 3 and CCN concentrations were higher during periods where the absolute humidity was less than 4.3 g <math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">H</mi><mn mathvariant="normal">2</mn></msub><mi mathvariant="normal">O</mi></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="650198b20b7d707e481c2cc77726cf67"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-9497-2021-ie00001.svg" width="18pt" height="10pt" src="acp-21-9497-2021-ie00001.png"/></svg:svg> /m 3 , indicative of free tropospheric or Antarctic continental air masses, compared to other periods of the voyage. Increased aerosol concentration in air masses originating close to the Antarctic coastline have been observed in numerous other studies. However, the smaller changes observed in the present analyses suggest seasonal differences in atmospheric circulation, including lesser impact of synoptic low-pressure systems in summer. Further measurements in the region are required before a more comprehensive picture of atmospheric circulation in this region can be captured and its influence on local aerosol populations understood. Text Antarc* Antarctic Sea ice Southern Ocean Copernicus Publications: E-Journals Antarctic Southern Ocean The Antarctic Atmospheric Chemistry and Physics 21 12 9497 9513 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Aerosol measurements over the Southern Ocean have been identified as critical to an improved understanding of aerosol–radiation and aerosol–cloud interactions, as there currently exists significant discrepancies between model results and measurements in this region. The atmosphere above the Southern Ocean provides crucial insight into an aerosol regime relatively free from anthropogenic influence, yet its remoteness ensures atmospheric measurements are relatively rare. Here we present observations from the Polar Cell Aerosol Nucleation (PCAN) campaign, hosted aboard the RV Investigator during a summer (January–March) 2017 voyage from Hobart, Australia, to the East Antarctic seasonal sea ice zone. A median particle number concentration (condensation nuclei > 3 nm; CN 3 ) of 354 (95 % CI 345–363) cm −3 was observed from the voyage. Median cloud condensation nuclei (CCN) concentrations were 167 (95 % CI 158–176) cm −3 . Measured particle size distributions suggested that aerosol populations had undergone significant cloud processing. To understand the variability in aerosol observations, measurements were classified by meteorological variables. Wind direction and absolute humidity were used to identify different air masses, and aerosol measurements were compared based on these identifications. CN 3 concentrations measured during SE wind directions (median 594 cm −3 ) were higher than those measured during wind directions from the NW (median 265 cm −3 ). Increased frequency of measurements from these wind directions suggests the influence of large-scale atmospheric transport mechanisms on the local aerosol population in the boundary layer of the East Antarctic seasonal ice zone. Modelled back trajectories imply different air mass histories for each measurement group, supporting this suggestion. CN 3 and CCN concentrations were higher during periods where the absolute humidity was less than 4.3 g <math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">H</mi><mn mathvariant="normal">2</mn></msub><mi mathvariant="normal">O</mi></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="650198b20b7d707e481c2cc77726cf67"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-9497-2021-ie00001.svg" width="18pt" height="10pt" src="acp-21-9497-2021-ie00001.png"/></svg:svg> /m 3 , indicative of free tropospheric or Antarctic continental air masses, compared to other periods of the voyage. Increased aerosol concentration in air masses originating close to the Antarctic coastline have been observed in numerous other studies. However, the smaller changes observed in the present analyses suggest seasonal differences in atmospheric circulation, including lesser impact of synoptic low-pressure systems in summer. Further measurements in the region are required before a more comprehensive picture of atmospheric circulation in this region can be captured and its influence on local aerosol populations understood. |
format |
Text |
author |
Simmons, Jack B. Humphries, Ruhi S. Wilson, Stephen R. Chambers, Scott D. Williams, Alastair G. Griffiths, Alan D. McRobert, Ian M. Ward, Jason P. Keywood, Melita D. Gribben, Sean |
spellingShingle |
Simmons, Jack B. Humphries, Ruhi S. Wilson, Stephen R. Chambers, Scott D. Williams, Alastair G. Griffiths, Alan D. McRobert, Ian M. Ward, Jason P. Keywood, Melita D. Gribben, Sean Summer aerosol measurements over the East Antarctic seasonal ice zone |
author_facet |
Simmons, Jack B. Humphries, Ruhi S. Wilson, Stephen R. Chambers, Scott D. Williams, Alastair G. Griffiths, Alan D. McRobert, Ian M. Ward, Jason P. Keywood, Melita D. Gribben, Sean |
author_sort |
Simmons, Jack B. |
title |
Summer aerosol measurements over the East Antarctic seasonal ice zone |
title_short |
Summer aerosol measurements over the East Antarctic seasonal ice zone |
title_full |
Summer aerosol measurements over the East Antarctic seasonal ice zone |
title_fullStr |
Summer aerosol measurements over the East Antarctic seasonal ice zone |
title_full_unstemmed |
Summer aerosol measurements over the East Antarctic seasonal ice zone |
title_sort |
summer aerosol measurements over the east antarctic seasonal ice zone |
publishDate |
2021 |
url |
https://doi.org/10.5194/acp-21-9497-2021 https://acp.copernicus.org/articles/21/9497/2021/ |
geographic |
Antarctic Southern Ocean The Antarctic |
geographic_facet |
Antarctic Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic Sea ice Southern Ocean |
op_source |
eISSN: 1680-7324 |
op_relation |
doi:10.5194/acp-21-9497-2021 https://acp.copernicus.org/articles/21/9497/2021/ |
op_doi |
https://doi.org/10.5194/acp-21-9497-2021 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
21 |
container_issue |
12 |
container_start_page |
9497 |
op_container_end_page |
9513 |
_version_ |
1766272446247206912 |