Atmospheric ionization by high-fluence, hard-spectrum solar proton events and their probable appearance in the ice core archive
Solar energetic particles ionize the atmosphere, leading to production of nitrogen oxides. It has been suggested that some such events are visible as layers of nitrate in ice cores, yielding archives of energetic, high-fluence solar proton events (SPEs). This has been controversial, due to slowness...
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Online Access: | http://hdl.handle.net/1808/25438 https://doi.org/10.1002/2015JD024064 |
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ftunivkansas:oai:kuscholarworks.ku.edu:1808/25438 2023-05-15T16:29:57+02:00 Atmospheric ionization by high-fluence, hard-spectrum solar proton events and their probable appearance in the ice core archive Melott, Adrian L. Thomas, Brian C. Laird, Claude M. Neuenswander, Benjamin Atri, Dimitra 2017-11-20T16:42:03Z http://hdl.handle.net/1808/25438 https://doi.org/10.1002/2015JD024064 unknown American Geophysical Union http://hdl.handle.net/1808/25438 doi:10.1002/2015JD024064 orcid:0000-0001-9091-0830 ©2016. American Geophysical Union. All Rights Reserved openAccess Ice cores Solar proton events Atmospheric ionization Article 2017 ftunivkansas https://doi.org/10.1002/2015JD024064 2022-08-26T13:22:34Z Solar energetic particles ionize the atmosphere, leading to production of nitrogen oxides. It has been suggested that some such events are visible as layers of nitrate in ice cores, yielding archives of energetic, high-fluence solar proton events (SPEs). This has been controversial, due to slowness of transport for these species down from the upper stratosphere; past numerical simulations based on an analytic calculation have shown very little ionization below the midstratosphere. These simulations suffer from deficiencies: they consider only soft SPEs and narrow energy ranges; spectral fits are poorly chosen; and with few exceptions secondary particles in air showers are ignored. Using improved simulations that follow development of the proton-induced air shower, we find consistency with recent experiments showing substantial excess ionization down to 5 km. We compute nitrate available from the 23 February 1956 SPE, which had a high-fluence, hard-spectrum, and well-resolved associated nitrate peak in a Greenland ice core. For the first time, we find that this event can account for ice core data with timely (~2 months) transport downward between 46 km and the surface, thus indicating an archive of high-fluence, hard-spectrum SPEs covering the last several millennia. We discuss interpretations of this result, as well as the lack of a clearly defined nitrate spike associated with the soft-spectrum 3–4 August 1972 SPE. We suggest that hard-spectrum SPEs, especially in the 6 months of polar winter, are detectable in ice cores and that more work needs to be done to investigate this. Article in Journal/Newspaper Greenland Greenland ice core ice core The University of Kansas: KU ScholarWorks Greenland Journal of Geophysical Research: Atmospheres 121 6 3017 3033 |
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Open Polar |
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The University of Kansas: KU ScholarWorks |
op_collection_id |
ftunivkansas |
language |
unknown |
topic |
Ice cores Solar proton events Atmospheric ionization |
spellingShingle |
Ice cores Solar proton events Atmospheric ionization Melott, Adrian L. Thomas, Brian C. Laird, Claude M. Neuenswander, Benjamin Atri, Dimitra Atmospheric ionization by high-fluence, hard-spectrum solar proton events and their probable appearance in the ice core archive |
topic_facet |
Ice cores Solar proton events Atmospheric ionization |
description |
Solar energetic particles ionize the atmosphere, leading to production of nitrogen oxides. It has been suggested that some such events are visible as layers of nitrate in ice cores, yielding archives of energetic, high-fluence solar proton events (SPEs). This has been controversial, due to slowness of transport for these species down from the upper stratosphere; past numerical simulations based on an analytic calculation have shown very little ionization below the midstratosphere. These simulations suffer from deficiencies: they consider only soft SPEs and narrow energy ranges; spectral fits are poorly chosen; and with few exceptions secondary particles in air showers are ignored. Using improved simulations that follow development of the proton-induced air shower, we find consistency with recent experiments showing substantial excess ionization down to 5 km. We compute nitrate available from the 23 February 1956 SPE, which had a high-fluence, hard-spectrum, and well-resolved associated nitrate peak in a Greenland ice core. For the first time, we find that this event can account for ice core data with timely (~2 months) transport downward between 46 km and the surface, thus indicating an archive of high-fluence, hard-spectrum SPEs covering the last several millennia. We discuss interpretations of this result, as well as the lack of a clearly defined nitrate spike associated with the soft-spectrum 3–4 August 1972 SPE. We suggest that hard-spectrum SPEs, especially in the 6 months of polar winter, are detectable in ice cores and that more work needs to be done to investigate this. |
format |
Article in Journal/Newspaper |
author |
Melott, Adrian L. Thomas, Brian C. Laird, Claude M. Neuenswander, Benjamin Atri, Dimitra |
author_facet |
Melott, Adrian L. Thomas, Brian C. Laird, Claude M. Neuenswander, Benjamin Atri, Dimitra |
author_sort |
Melott, Adrian L. |
title |
Atmospheric ionization by high-fluence, hard-spectrum solar proton events and their probable appearance in the ice core archive |
title_short |
Atmospheric ionization by high-fluence, hard-spectrum solar proton events and their probable appearance in the ice core archive |
title_full |
Atmospheric ionization by high-fluence, hard-spectrum solar proton events and their probable appearance in the ice core archive |
title_fullStr |
Atmospheric ionization by high-fluence, hard-spectrum solar proton events and their probable appearance in the ice core archive |
title_full_unstemmed |
Atmospheric ionization by high-fluence, hard-spectrum solar proton events and their probable appearance in the ice core archive |
title_sort |
atmospheric ionization by high-fluence, hard-spectrum solar proton events and their probable appearance in the ice core archive |
publisher |
American Geophysical Union |
publishDate |
2017 |
url |
http://hdl.handle.net/1808/25438 https://doi.org/10.1002/2015JD024064 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Greenland ice core ice core |
genre_facet |
Greenland Greenland ice core ice core |
op_relation |
http://hdl.handle.net/1808/25438 doi:10.1002/2015JD024064 orcid:0000-0001-9091-0830 |
op_rights |
©2016. American Geophysical Union. All Rights Reserved openAccess |
op_doi |
https://doi.org/10.1002/2015JD024064 |
container_title |
Journal of Geophysical Research: Atmospheres |
container_volume |
121 |
container_issue |
6 |
container_start_page |
3017 |
op_container_end_page |
3033 |
_version_ |
1766019654584631296 |