Formation of large NAT particles and denitrification in polar stratosphere: possible role of cosmic rays and effect of solar activity
The formation of large nitric acid trihydrate (NAT) particles has important implications for denitrification and ozone depletion. Existing theories have difficulty in explaining the formation of large NAT particles at temperatures above the ice frost point, which has been observed recently over wide...
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ftcopernicus:oai:publications.copernicus.org:acp3645 2023-05-15T15:11:09+02:00 Formation of large NAT particles and denitrification in polar stratosphere: possible role of cosmic rays and effect of solar activity Yu, F. 2018-06-28 application/pdf https://doi.org/10.5194/acp-4-2273-2004 https://www.atmos-chem-phys.net/4/2273/2004/ eng eng doi:10.5194/acp-4-2273-2004 https://www.atmos-chem-phys.net/4/2273/2004/ eISSN: 1680-7324 Text 2018 ftcopernicus https://doi.org/10.5194/acp-4-2273-2004 2019-12-24T09:59:15Z The formation of large nitric acid trihydrate (NAT) particles has important implications for denitrification and ozone depletion. Existing theories have difficulty in explaining the formation of large NAT particles at temperatures above the ice frost point, which has been observed recently over wide Arctic regions. Our analyses reveal that high-energy comic ray particles might induce the freezing of supercooled HNO 3 -H 2 O-H 2 SO 4 droplets when they penetrate these thermodynamically unstable droplets. The cosmic ray-induced freezing (CRIF) appears to be consistent with the observed, highly selective formation of NAT particles. We suggest a possible physical process behind the CRIF mechanism: the reorientation of polar solution molecules into the crystalline configuration in the strong electrical fields of moving secondary ions generated by passing cosmic rays. A simple formula connecting the CRIF rate to cosmic ray flux is derived with an undefined parameter constrained by observed NAT formation rates. Our simulations indicate that strong solar proton events (SPEs) may significantly enhance the formation of large NAT particles and denitrification. The CRIF mechanism offers a possible explanation for the observed high correlations between the thin nitrate-rich layers in polar ice cores and major SPEs, and the observed enhancement in the aerosol backscattering ratio at PSC layers shortly after an SPE and the significant precipitation velocity of the enhanced PSC layers. The key uncertainty in the CRIF mechanism is the probability ( P ) of freezing when a CR particle hits a thermodynamically, unstable STS droplet. Further studies are needed to either confirm or reject the CRIF hypothesis. Text Arctic Copernicus Publications: E-Journals Arctic Atmospheric Chemistry and Physics 4 9/10 2273 2283 |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
The formation of large nitric acid trihydrate (NAT) particles has important implications for denitrification and ozone depletion. Existing theories have difficulty in explaining the formation of large NAT particles at temperatures above the ice frost point, which has been observed recently over wide Arctic regions. Our analyses reveal that high-energy comic ray particles might induce the freezing of supercooled HNO 3 -H 2 O-H 2 SO 4 droplets when they penetrate these thermodynamically unstable droplets. The cosmic ray-induced freezing (CRIF) appears to be consistent with the observed, highly selective formation of NAT particles. We suggest a possible physical process behind the CRIF mechanism: the reorientation of polar solution molecules into the crystalline configuration in the strong electrical fields of moving secondary ions generated by passing cosmic rays. A simple formula connecting the CRIF rate to cosmic ray flux is derived with an undefined parameter constrained by observed NAT formation rates. Our simulations indicate that strong solar proton events (SPEs) may significantly enhance the formation of large NAT particles and denitrification. The CRIF mechanism offers a possible explanation for the observed high correlations between the thin nitrate-rich layers in polar ice cores and major SPEs, and the observed enhancement in the aerosol backscattering ratio at PSC layers shortly after an SPE and the significant precipitation velocity of the enhanced PSC layers. The key uncertainty in the CRIF mechanism is the probability ( P ) of freezing when a CR particle hits a thermodynamically, unstable STS droplet. Further studies are needed to either confirm or reject the CRIF hypothesis. |
format |
Text |
author |
Yu, F. |
spellingShingle |
Yu, F. Formation of large NAT particles and denitrification in polar stratosphere: possible role of cosmic rays and effect of solar activity |
author_facet |
Yu, F. |
author_sort |
Yu, F. |
title |
Formation of large NAT particles and denitrification in polar stratosphere: possible role of cosmic rays and effect of solar activity |
title_short |
Formation of large NAT particles and denitrification in polar stratosphere: possible role of cosmic rays and effect of solar activity |
title_full |
Formation of large NAT particles and denitrification in polar stratosphere: possible role of cosmic rays and effect of solar activity |
title_fullStr |
Formation of large NAT particles and denitrification in polar stratosphere: possible role of cosmic rays and effect of solar activity |
title_full_unstemmed |
Formation of large NAT particles and denitrification in polar stratosphere: possible role of cosmic rays and effect of solar activity |
title_sort |
formation of large nat particles and denitrification in polar stratosphere: possible role of cosmic rays and effect of solar activity |
publishDate |
2018 |
url |
https://doi.org/10.5194/acp-4-2273-2004 https://www.atmos-chem-phys.net/4/2273/2004/ |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
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Arctic |
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eISSN: 1680-7324 |
op_relation |
doi:10.5194/acp-4-2273-2004 https://www.atmos-chem-phys.net/4/2273/2004/ |
op_doi |
https://doi.org/10.5194/acp-4-2273-2004 |
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Atmospheric Chemistry and Physics |
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4 |
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9/10 |
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2273 |
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2283 |
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1766342053972672512 |