Structure, variability, and origin of the low-latitude nightglow continuum between 300 and 1800&thinsp;nm: evidence for HO<sub>2</sub> emission in the near-infrared

<p>The Earth's mesopause region between about 75 and 105 <span class="inline-formula">km</span> is characterised by chemiluminescent emission from various lines of different molecules and atoms. This emission was and is important for the study of the chemistry and dy...

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Main Authors: S. Noll, J. M. C. Plane, W. Feng, K. S. Kalogerakis, W. Kausch, C. Schmidt, M. Bittner, S. Kimeswenger
Format: Article
Language:English
Published: Copernicus Publications 2024-01-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/24/1143/2024/acp-24-1143-2024.pdf
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author S. Noll
S. Noll
J. M. C. Plane
W. Feng
W. Feng
K. S. Kalogerakis
W. Kausch
C. Schmidt
M. Bittner
M. Bittner
S. Kimeswenger
S. Kimeswenger
author_facet S. Noll
S. Noll
J. M. C. Plane
W. Feng
W. Feng
K. S. Kalogerakis
W. Kausch
C. Schmidt
M. Bittner
M. Bittner
S. Kimeswenger
S. Kimeswenger
author_sort S. Noll
collection DOAJ
description <p>The Earth's mesopause region between about 75 and 105 <span class="inline-formula">km</span> is characterised by chemiluminescent emission from various lines of different molecules and atoms. This emission was and is important for the study of the chemistry and dynamics in this altitude region at nighttime. However, our understanding is still very limited with respect to molecular emissions with low intensities and high line densities that are challenging to resolve. Based on 10 years of data from the astronomical X-shooter echelle spectrograph at Cerro Paranal in Chile, we have characterised in detail this nightglow (pseudo-)continuum in the wavelength range from 300 to 1800 <span class="inline-formula">nm</span>. We studied the spectral features, derived continuum components with similar variability, calculated climatologies, studied the response to solar activity, and even estimated the effective emission heights. The results indicate that the nightglow continuum at Cerro Paranal essentially consists of only two components, which exhibit very different properties. The main structures of these components peak at 595 and 1510 <span class="inline-formula">nm</span>. While the former was previously identified as the main peak of the <span class="inline-formula">FeO</span> “orange arc” bands, the latter is a new discovery. Laboratory data and theory indicate that this feature and other structures between about 800 and at least 1800 <span class="inline-formula">nm</span> are caused by emission from the low-lying <span class="inline-formula">A<sup>′′</sup></span> and <span class="inline-formula">A<sup>′</sup></span> states of <span class="inline-formula">HO<sub>2</sub></span>. In order to test this assumption, we performed runs with the Whole Atmosphere Community Climate Model (WACCM) with modified chemistry and found that the total intensity, layer profile, and variability indeed support this interpretation, where the excited <span class="inline-formula">HO<sub>2</sub></span> radicals are mostly produced from the termolecular recombination of <span class="inline-formula">H</span> and <span class="inline-formula">O<sub>2</sub></span>. The WACCM results for the continuum component that dominates at visual wavelengths show good agreement for <span class="inline-formula">FeO</span> from the reaction of <span class="inline-formula">Fe</span> and <span class="inline-formula">O<sub>3</sub></span>. However, the simulated total emission appears to be too low, which would require additional mechanisms where the variability is dominated by <span class="inline-formula">O<sub>3</sub></span>. A possible (but nevertheless insufficient) process could be the production of excited <span class="inline-formula">OFeOH</span> by the reaction of <span class="inline-formula">FeOH</span> and <span class="inline-formula">O<sub>3</sub></span>.</p>
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spelling doaj.art-50ec1a0ad9684c8c852beca464d5a1c42024-01-26T08:26:10ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242024-01-01241143117610.5194/acp-24-1143-2024Structure, variability, and origin of the low-latitude nightglow continuum between 300 and 1800&thinsp;nm: evidence for HO<sub>2</sub> emission in the near-infraredS. Noll0S. Noll1J. M. C. Plane2W. Feng3W. Feng4K. S. Kalogerakis5W. Kausch6C. Schmidt7M. Bittner8M. Bittner9S. Kimeswenger10S. Kimeswenger11Institut für Physik, Universität Augsburg, Augsburg, GermanyDeutsches Fernerkundungsdatenzentrum, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, GermanySchool of Chemistry, University of Leeds, Leeds, UKSchool of Chemistry, University of Leeds, Leeds, UKNational Centre for Atmospheric Science, University of Leeds, Leeds, UKCenter for Geospace Studies, SRI International, Menlo Park, CA, USAInstitut für Astro- und Teilchenphysik, Universität Innsbruck, Innsbruck, AustriaDeutsches Fernerkundungsdatenzentrum, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, GermanyInstitut für Physik, Universität Augsburg, Augsburg, GermanyDeutsches Fernerkundungsdatenzentrum, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, GermanyInstitut für Astro- und Teilchenphysik, Universität Innsbruck, Innsbruck, AustriaInstituto de Astronomía, Universidad Católica del Norte, Antofagasta, Chile<p>The Earth's mesopause region between about 75 and 105 <span class="inline-formula">km</span> is characterised by chemiluminescent emission from various lines of different molecules and atoms. This emission was and is important for the study of the chemistry and dynamics in this altitude region at nighttime. However, our understanding is still very limited with respect to molecular emissions with low intensities and high line densities that are challenging to resolve. Based on 10 years of data from the astronomical X-shooter echelle spectrograph at Cerro Paranal in Chile, we have characterised in detail this nightglow (pseudo-)continuum in the wavelength range from 300 to 1800 <span class="inline-formula">nm</span>. We studied the spectral features, derived continuum components with similar variability, calculated climatologies, studied the response to solar activity, and even estimated the effective emission heights. The results indicate that the nightglow continuum at Cerro Paranal essentially consists of only two components, which exhibit very different properties. The main structures of these components peak at 595 and 1510 <span class="inline-formula">nm</span>. While the former was previously identified as the main peak of the <span class="inline-formula">FeO</span> “orange arc” bands, the latter is a new discovery. Laboratory data and theory indicate that this feature and other structures between about 800 and at least 1800 <span class="inline-formula">nm</span> are caused by emission from the low-lying <span class="inline-formula">A<sup>′′</sup></span> and <span class="inline-formula">A<sup>′</sup></span> states of <span class="inline-formula">HO<sub>2</sub></span>. In order to test this assumption, we performed runs with the Whole Atmosphere Community Climate Model (WACCM) with modified chemistry and found that the total intensity, layer profile, and variability indeed support this interpretation, where the excited <span class="inline-formula">HO<sub>2</sub></span> radicals are mostly produced from the termolecular recombination of <span class="inline-formula">H</span> and <span class="inline-formula">O<sub>2</sub></span>. The WACCM results for the continuum component that dominates at visual wavelengths show good agreement for <span class="inline-formula">FeO</span> from the reaction of <span class="inline-formula">Fe</span> and <span class="inline-formula">O<sub>3</sub></span>. However, the simulated total emission appears to be too low, which would require additional mechanisms where the variability is dominated by <span class="inline-formula">O<sub>3</sub></span>. A possible (but nevertheless insufficient) process could be the production of excited <span class="inline-formula">OFeOH</span> by the reaction of <span class="inline-formula">FeOH</span> and <span class="inline-formula">O<sub>3</sub></span>.</p>https://acp.copernicus.org/articles/24/1143/2024/acp-24-1143-2024.pdf
spellingShingle S. Noll
S. Noll
J. M. C. Plane
W. Feng
W. Feng
K. S. Kalogerakis
W. Kausch
C. Schmidt
M. Bittner
M. Bittner
S. Kimeswenger
S. Kimeswenger
Structure, variability, and origin of the low-latitude nightglow continuum between 300 and 1800&thinsp;nm: evidence for HO<sub>2</sub> emission in the near-infrared
Atmospheric Chemistry and Physics
title Structure, variability, and origin of the low-latitude nightglow continuum between 300 and 1800&thinsp;nm: evidence for HO<sub>2</sub> emission in the near-infrared
title_full Structure, variability, and origin of the low-latitude nightglow continuum between 300 and 1800&thinsp;nm: evidence for HO<sub>2</sub> emission in the near-infrared
title_fullStr Structure, variability, and origin of the low-latitude nightglow continuum between 300 and 1800&thinsp;nm: evidence for HO<sub>2</sub> emission in the near-infrared
title_full_unstemmed Structure, variability, and origin of the low-latitude nightglow continuum between 300 and 1800&thinsp;nm: evidence for HO<sub>2</sub> emission in the near-infrared
title_short Structure, variability, and origin of the low-latitude nightglow continuum between 300 and 1800&thinsp;nm: evidence for HO<sub>2</sub> emission in the near-infrared
title_sort structure variability and origin of the low latitude nightglow continuum between 300 and 1800 thinsp nm evidence for ho sub 2 sub emission in the near infrared
url https://acp.copernicus.org/articles/24/1143/2024/acp-24-1143-2024.pdf
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