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. Previous springtime measurements...
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ftcopernicus:oai:publications.copernicus.org:acpd91413 2023-05-15T13:31:39+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 2020-11-26 application/pdf https://doi.org/10.5194/acp-2020-1213 https://acp.copernicus.org/preprints/acp-2020-1213/ eng eng doi:10.5194/acp-2020-1213 https://acp.copernicus.org/preprints/acp-2020-1213/ eISSN: 1680-7324 Text 2020 ftcopernicus https://doi.org/10.5194/acp-2020-1213 2020-11-30T17:22:13Z 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. Previous springtime measurements from the East Antarctic seasonal ice zone revealed a significant increase in aerosol number concentrations when crossing the atmospheric polar front into the Polar cell. A return voyage in summer 2017 made a more extensive range of aerosols measurements, including in particular aerosol number concentrations and submicron size distributions. Again, significantly greater aerosol number concentrations were observed in the Polar cell than in the Ferrel cell. Unlike the previous spring voyage however, the polar front was unable to be identified by a step change in aerosol concentration. A possible explanation is that atmospheric mixing across the polar front occurs to a greater degree in summer, therefore weakening the atmospheric boundary at the front. This atmospheric mixing in summer complicates the determination of the polar front location. These changes, together with the increased source of precursors from phytoplankton emissions, are likely to explain the seasonal differences observed in the magnitude of aerosol populations between the Ferrel and Polar cell. In the present analysis, meteorological variables were used to identify different air-masses and then aerosol measurements were compared based on these identifications. CN 3 concentrations measured during wind directions indicative of Polar cell airmasses (median 594 cm −3 ) were larger than those measured during wind directions indicative of Ferrel cell air (median 265 cm −3 ). CN 3 and CCN concentrations were larger during periods where the absolute humidity was less than 4.3 g H 2 O /m 3 , indicative of free tropospheric or Antarctic continental airmasses, compared to other periods of the voyage. These results indicate that a persistently more concentrated aerosol population is present in the Polar cell over the East Antarctic seasonal ice zone, although the observed difference between the two cells may vary seasonally. Text Antarc* Antarctic Southern Ocean Copernicus Publications: E-Journals Antarctic Southern Ocean |
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Open Polar |
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Copernicus Publications: E-Journals |
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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. Previous springtime measurements from the East Antarctic seasonal ice zone revealed a significant increase in aerosol number concentrations when crossing the atmospheric polar front into the Polar cell. A return voyage in summer 2017 made a more extensive range of aerosols measurements, including in particular aerosol number concentrations and submicron size distributions. Again, significantly greater aerosol number concentrations were observed in the Polar cell than in the Ferrel cell. Unlike the previous spring voyage however, the polar front was unable to be identified by a step change in aerosol concentration. A possible explanation is that atmospheric mixing across the polar front occurs to a greater degree in summer, therefore weakening the atmospheric boundary at the front. This atmospheric mixing in summer complicates the determination of the polar front location. These changes, together with the increased source of precursors from phytoplankton emissions, are likely to explain the seasonal differences observed in the magnitude of aerosol populations between the Ferrel and Polar cell. In the present analysis, meteorological variables were used to identify different air-masses and then aerosol measurements were compared based on these identifications. CN 3 concentrations measured during wind directions indicative of Polar cell airmasses (median 594 cm −3 ) were larger than those measured during wind directions indicative of Ferrel cell air (median 265 cm −3 ). CN 3 and CCN concentrations were larger during periods where the absolute humidity was less than 4.3 g H 2 O /m 3 , indicative of free tropospheric or Antarctic continental airmasses, compared to other periods of the voyage. These results indicate that a persistently more concentrated aerosol population is present in the Polar cell over the East Antarctic seasonal ice zone, although the observed difference between the two cells may vary seasonally. |
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 |
2020 |
url |
https://doi.org/10.5194/acp-2020-1213 https://acp.copernicus.org/preprints/acp-2020-1213/ |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_source |
eISSN: 1680-7324 |
op_relation |
doi:10.5194/acp-2020-1213 https://acp.copernicus.org/preprints/acp-2020-1213/ |
op_doi |
https://doi.org/10.5194/acp-2020-1213 |
_version_ |
1766019870631133184 |