Photochemistry on the bottom side of the mesospheric Na layer
<p>Lidar observations of the mesospheric Na layer have revealed considerable diurnal variations, particularly on the bottom side of the layer, where more than an order-of-magnitude increase in Na density has been observed below 80 km after sunrise. In this paper, multi-year Na lidar...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2019-03-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/3769/2019/acp-19-3769-2019.pdf |
| _version_ | 1818961603778838528 |
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| author | T. Yuan T. Yuan W. Feng W. Feng J. M. C. Plane D. R. Marsh D. R. Marsh |
| author_facet | T. Yuan T. Yuan W. Feng W. Feng J. M. C. Plane D. R. Marsh D. R. Marsh |
| author_sort | T. Yuan |
| collection | DOAJ |
| description | <p>Lidar observations of the mesospheric Na layer have revealed considerable
diurnal variations, particularly on the bottom side of the layer, where more
than an order-of-magnitude increase in Na density has been observed below 80 km
after sunrise. In this paper, multi-year Na lidar observations are
utilized over a full diurnal cycle at Utah State University (USU) (41.8<span class="inline-formula"><sup>∘</sup></span> N,
111.8<span class="inline-formula"><sup>∘</sup></span> W) and a global atmospheric model of Na with 0.5 km
vertical resolution in the mesosphere and lower thermosphere (WACCM-Na) to explore
the dramatic changes of Na density on the bottom side of the layer. Photolysis of the principal reservoir <span class="inline-formula">NaHCO<sub>3</sub></span> is shown to be
primarily responsible for the increase in Na after sunrise, amplified by the
increased rate of reaction of <span class="inline-formula">NaHCO<sub>3</sub></span> with atomic H, which is mainly
produced from the photolysis of <span class="inline-formula">H<sub>2</sub>O</span> and the reaction of OH with
<span class="inline-formula">O<sub>3</sub></span>. This finding is further supported by Na lidar observation at USU
during the solar eclipse (<span class="inline-formula">>96</span> % totality) event on 21 August 2017, when a decrease and recovery of the Na density on the
bottom side of the layer were observed. Lastly, the model simulation shows
that the Fe density below around 80 km increases more strongly and earlier
than observed Na changes during sunrise because of the considerably faster
photolysis rate of its major reservoir of FeOH.</p> |
| first_indexed | 2024-12-20T12:16:04Z |
| format | Article |
| id | doaj.art-911dd37ab0594e74b069f1d57c5749ed |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-20T12:16:04Z |
| publishDate | 2019-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-911dd37ab0594e74b069f1d57c5749ed2022-12-21T19:41:07ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242019-03-01193769377710.5194/acp-19-3769-2019Photochemistry on the bottom side of the mesospheric Na layerT. Yuan0T. Yuan1W. Feng2W. Feng3J. M. C. Plane4D. R. Marsh5D. R. Marsh6Physics Department, Utah State University, Logan, Utah, USACenter for Atmospheric and Space Sciences, Utah State University, Logan, Utah, USASchool of Chemistry, University of Leeds, Leeds, UKNational Centre for Atmospheric Science, University of Leeds, Leeds, UKSchool of Chemistry, University of Leeds, Leeds, UKSchool of Chemistry, University of Leeds, Leeds, UKNational Center for Atmospheric Research, Boulder, Colorado, USA<p>Lidar observations of the mesospheric Na layer have revealed considerable diurnal variations, particularly on the bottom side of the layer, where more than an order-of-magnitude increase in Na density has been observed below 80 km after sunrise. In this paper, multi-year Na lidar observations are utilized over a full diurnal cycle at Utah State University (USU) (41.8<span class="inline-formula"><sup>∘</sup></span> N, 111.8<span class="inline-formula"><sup>∘</sup></span> W) and a global atmospheric model of Na with 0.5 km vertical resolution in the mesosphere and lower thermosphere (WACCM-Na) to explore the dramatic changes of Na density on the bottom side of the layer. Photolysis of the principal reservoir <span class="inline-formula">NaHCO<sub>3</sub></span> is shown to be primarily responsible for the increase in Na after sunrise, amplified by the increased rate of reaction of <span class="inline-formula">NaHCO<sub>3</sub></span> with atomic H, which is mainly produced from the photolysis of <span class="inline-formula">H<sub>2</sub>O</span> and the reaction of OH with <span class="inline-formula">O<sub>3</sub></span>. This finding is further supported by Na lidar observation at USU during the solar eclipse (<span class="inline-formula">>96</span> % totality) event on 21 August 2017, when a decrease and recovery of the Na density on the bottom side of the layer were observed. Lastly, the model simulation shows that the Fe density below around 80 km increases more strongly and earlier than observed Na changes during sunrise because of the considerably faster photolysis rate of its major reservoir of FeOH.</p>https://www.atmos-chem-phys.net/19/3769/2019/acp-19-3769-2019.pdf |
| spellingShingle | T. Yuan T. Yuan W. Feng W. Feng J. M. C. Plane D. R. Marsh D. R. Marsh Photochemistry on the bottom side of the mesospheric Na layer Atmospheric Chemistry and Physics |
| title | Photochemistry on the bottom side of the mesospheric Na layer |
| title_full | Photochemistry on the bottom side of the mesospheric Na layer |
| title_fullStr | Photochemistry on the bottom side of the mesospheric Na layer |
| title_full_unstemmed | Photochemistry on the bottom side of the mesospheric Na layer |
| title_short | Photochemistry on the bottom side of the mesospheric Na layer |
| title_sort | photochemistry on the bottom side of the mesospheric na layer |
| url | https://www.atmos-chem-phys.net/19/3769/2019/acp-19-3769-2019.pdf |
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