The meteorology and chemistry of high nitrogen oxide concentrations in the stable boundary layer at the South Pole
Four summer seasons of nitrogen oxide (NO) concentrations were obtained at the South Pole (SP) during the Sulfur Chemistry in the Antarctic Troposphere (ISCAT) program (1998 and 2000) and the Antarctic Tropospheric Chemistry Investigation (ANTCI) in (2003, 2005, 2006–2007). Together, analyses of the...
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Copernicus Publications
2018
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article Verlagsveröffentlichung Neff, William Crawford, Jim Buhr, Marty Nicovich, John Chen, Gao Davis, Douglas The meteorology and chemistry of high nitrogen oxide concentrations in the stable boundary layer at the South Pole |
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article Verlagsveröffentlichung |
description |
Four summer seasons of nitrogen oxide (NO) concentrations were obtained at the South Pole (SP) during the Sulfur Chemistry in the Antarctic Troposphere (ISCAT) program (1998 and 2000) and the Antarctic Tropospheric Chemistry Investigation (ANTCI) in (2003, 2005, 2006–2007). Together, analyses of the data collected from these studies provide insight into the large- to small-scale meteorology that sets the stage for extremes in NO and the significant variability that occurs day to day, within seasons, and year to year. In addition, these observations reveal the interplay between physical and chemical processes at work in the stable boundary layer of the high Antarctic plateau. We found a systematic evolution of the large-scale wind system over the ice sheet from winter to summer that controls the surface boundary layer and its effect on NO: initially in early spring (Days 280–310) the transport of warm air and clouds over West Antarctica dominates the environment over the SP; in late spring (Days 310–340), the winds at 300 hPa exhibit a bimodal behavior alternating between northwest and southeast quadrants, which is of significance to NO; in early summer (Days 340–375), the flow aloft is dominated by winds from the Weddell Sea; and finally, during late spring, winds aloft from the southeast are strongly associated with clear skies, shallow stable boundary layers, and light surface winds from the east – it is under these conditions that the highest NO occurs. Examination of the winds at 300 hPa from 1961 to 2013 shows that this seasonal pattern has not changed significantly, although the last twenty years have seen an increasing trend in easterly surface winds at the SP. What has also changed is the persistence of the ozone hole, often into early summer. With lower total ozone column density and higher sun elevation, the highest actinic flux responsible for the photolysis of snow nitrate now occurs in late spring under the shallow boundary layer conditions optimum for high accumulation of NO. This may occur via the non-linear HOX–NOx chemistry proposed after the first ISCAT field programs and NOx recycling to the surface where quantum yields may be large under the low-snow-accumulation regime of the Antarctic plateau. During the 2003 field program a sodar made direct measurements of the stable boundary layer depth (BLD), a key factor in explaining the chemistry of the high NO concentrations. Because direct measurements were not available in the other years, we developed an estimator for BLD using direct observations obtained in 2003 and step-wise linear regression with meteorological data from a 22 m tower (that was tested against independent data obtained in 1993). These data were then used with assumptions about the column abundance of NO to estimate surface fluxes of NOx. These results agreed in magnitude with results at Concordia Station and confirmed significant daily, intraseasonal and interannual variability in NO and its flux from the snow surface. Finally, we found that synoptic to mesoscale eddies governed the boundary layer circulation and accumulation pathways for NO at the SP rather than katabatic forcing. It was the small-scale features of the circulation including the transition from cloudy to clear conditions that set the stage for short-term extremes in NO, whereas larger-scale features were associated with more moderate concentrations. |
format |
Article in Journal/Newspaper |
author |
Neff, William Crawford, Jim Buhr, Marty Nicovich, John Chen, Gao Davis, Douglas |
author_facet |
Neff, William Crawford, Jim Buhr, Marty Nicovich, John Chen, Gao Davis, Douglas |
author_sort |
Neff, William |
title |
The meteorology and chemistry of high nitrogen oxide concentrations in the stable boundary layer at the South Pole |
title_short |
The meteorology and chemistry of high nitrogen oxide concentrations in the stable boundary layer at the South Pole |
title_full |
The meteorology and chemistry of high nitrogen oxide concentrations in the stable boundary layer at the South Pole |
title_fullStr |
The meteorology and chemistry of high nitrogen oxide concentrations in the stable boundary layer at the South Pole |
title_full_unstemmed |
The meteorology and chemistry of high nitrogen oxide concentrations in the stable boundary layer at the South Pole |
title_sort |
meteorology and chemistry of high nitrogen oxide concentrations in the stable boundary layer at the south pole |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/acp-18-3755-2018 https://noa.gwlb.de/receive/cop_mods_00041887 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00041507/acp-18-3755-2018.pdf https://acp.copernicus.org/articles/18/3755/2018/acp-18-3755-2018.pdf |
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ENVELOPE(123.333,123.333,-75.100,-75.100) |
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Antarctic Concordia Station South Pole The Antarctic Weddell Weddell Sea West Antarctica |
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Antarctic Concordia Station South Pole The Antarctic Weddell Weddell Sea West Antarctica |
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Antarc* Antarctic Antarctica Ice Sheet South pole South pole Weddell Sea West Antarctica |
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Antarc* Antarctic Antarctica Ice Sheet South pole South pole Weddell Sea West Antarctica |
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Atmospheric Chemistry and Physics -- http://www.atmos-chem-phys.net/volumes_and_issues.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2069847 -- 1680-7324 https://doi.org/10.5194/acp-18-3755-2018 https://noa.gwlb.de/receive/cop_mods_00041887 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00041507/acp-18-3755-2018.pdf https://acp.copernicus.org/articles/18/3755/2018/acp-18-3755-2018.pdf |
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https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
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CC-BY |
op_doi |
https://doi.org/10.5194/acp-18-3755-2018 |
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Atmospheric Chemistry and Physics |
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18 |
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5 |
container_start_page |
3755 |
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3778 |
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00041887 2023-05-15T14:02:33+02:00 The meteorology and chemistry of high nitrogen oxide concentrations in the stable boundary layer at the South Pole Neff, William Crawford, Jim Buhr, Marty Nicovich, John Chen, Gao Davis, Douglas 2018-03 electronic https://doi.org/10.5194/acp-18-3755-2018 https://noa.gwlb.de/receive/cop_mods_00041887 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00041507/acp-18-3755-2018.pdf https://acp.copernicus.org/articles/18/3755/2018/acp-18-3755-2018.pdf eng eng Copernicus Publications Atmospheric Chemistry and Physics -- http://www.atmos-chem-phys.net/volumes_and_issues.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2069847 -- 1680-7324 https://doi.org/10.5194/acp-18-3755-2018 https://noa.gwlb.de/receive/cop_mods_00041887 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00041507/acp-18-3755-2018.pdf https://acp.copernicus.org/articles/18/3755/2018/acp-18-3755-2018.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess CC-BY article Verlagsveröffentlichung article Text doc-type:article 2018 ftnonlinearchiv https://doi.org/10.5194/acp-18-3755-2018 2022-02-08T22:41:21Z Four summer seasons of nitrogen oxide (NO) concentrations were obtained at the South Pole (SP) during the Sulfur Chemistry in the Antarctic Troposphere (ISCAT) program (1998 and 2000) and the Antarctic Tropospheric Chemistry Investigation (ANTCI) in (2003, 2005, 2006–2007). Together, analyses of the data collected from these studies provide insight into the large- to small-scale meteorology that sets the stage for extremes in NO and the significant variability that occurs day to day, within seasons, and year to year. In addition, these observations reveal the interplay between physical and chemical processes at work in the stable boundary layer of the high Antarctic plateau. We found a systematic evolution of the large-scale wind system over the ice sheet from winter to summer that controls the surface boundary layer and its effect on NO: initially in early spring (Days 280–310) the transport of warm air and clouds over West Antarctica dominates the environment over the SP; in late spring (Days 310–340), the winds at 300 hPa exhibit a bimodal behavior alternating between northwest and southeast quadrants, which is of significance to NO; in early summer (Days 340–375), the flow aloft is dominated by winds from the Weddell Sea; and finally, during late spring, winds aloft from the southeast are strongly associated with clear skies, shallow stable boundary layers, and light surface winds from the east – it is under these conditions that the highest NO occurs. Examination of the winds at 300 hPa from 1961 to 2013 shows that this seasonal pattern has not changed significantly, although the last twenty years have seen an increasing trend in easterly surface winds at the SP. What has also changed is the persistence of the ozone hole, often into early summer. With lower total ozone column density and higher sun elevation, the highest actinic flux responsible for the photolysis of snow nitrate now occurs in late spring under the shallow boundary layer conditions optimum for high accumulation of NO. This may occur via the non-linear HOX–NOx chemistry proposed after the first ISCAT field programs and NOx recycling to the surface where quantum yields may be large under the low-snow-accumulation regime of the Antarctic plateau. During the 2003 field program a sodar made direct measurements of the stable boundary layer depth (BLD), a key factor in explaining the chemistry of the high NO concentrations. Because direct measurements were not available in the other years, we developed an estimator for BLD using direct observations obtained in 2003 and step-wise linear regression with meteorological data from a 22 m tower (that was tested against independent data obtained in 1993). These data were then used with assumptions about the column abundance of NO to estimate surface fluxes of NOx. These results agreed in magnitude with results at Concordia Station and confirmed significant daily, intraseasonal and interannual variability in NO and its flux from the snow surface. Finally, we found that synoptic to mesoscale eddies governed the boundary layer circulation and accumulation pathways for NO at the SP rather than katabatic forcing. It was the small-scale features of the circulation including the transition from cloudy to clear conditions that set the stage for short-term extremes in NO, whereas larger-scale features were associated with more moderate concentrations. Article in Journal/Newspaper Antarc* Antarctic Antarctica Ice Sheet South pole South pole Weddell Sea West Antarctica Niedersächsisches Online-Archiv NOA Antarctic Concordia Station ENVELOPE(123.333,123.333,-75.100,-75.100) South Pole The Antarctic Weddell Weddell Sea West Antarctica Atmospheric Chemistry and Physics 18 5 3755 3778 |