Noctilucent clouds and the mesospheric water vapour: the past decade
The topic of this paper is the sensitivity of the brightness of noctilucent clouds (NLC) on the ambient water vapour mixing ratio f(H 2 O). Firstly, we use state-of-the-art models of NLC layer formation to predict NLC brightness changes in response to changes in the 80km mixing ratio f(H 2 O) for th...
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ftcopernicus:oai:publications.copernicus.org:acp3803 2023-05-15T13:11:23+02:00 Noctilucent clouds and the mesospheric water vapour: the past decade Zahn, U. Baumgarten, G. Berger, U. Fiedler, J. Hartogh, P. 2018-06-28 application/pdf https://doi.org/10.5194/acp-4-2449-2004 https://www.atmos-chem-phys.net/4/2449/2004/ eng eng doi:10.5194/acp-4-2449-2004 https://www.atmos-chem-phys.net/4/2449/2004/ eISSN: 1680-7324 Text 2018 ftcopernicus https://doi.org/10.5194/acp-4-2449-2004 2019-12-24T09:59:15Z The topic of this paper is the sensitivity of the brightness of noctilucent clouds (NLC) on the ambient water vapour mixing ratio f(H 2 O). Firstly, we use state-of-the-art models of NLC layer formation to predict NLC brightness changes in response to changes in the 80km mixing ratio f(H 2 O) for the two cases of ground-based 532nm lidar observations at 69° N and for hemispheric satellite SBUV observations at 252nm wavelength. In this study, we include a re-evaluation of the sensitivity of NLC brightness to changes in solar Lyman α flux. Secondly, we review observations of episodic changes in f(H 2 O) and those in NLC brightness, the former being available since 1992, the latter since 1979. To this review, we add a new series of observations of f(H 2 O), performed in the Arctic summer at the ALOMAR observatory. The episodic change exhibited by the Arctic summer means of f(H 2 O) turns out to be quite different from all those derived from annual means of f(H 2 O). The latter indicate that since 1996 a significant reduction of annually averaged upper mesospheric water vapour has occurred at low, mid, and high latitudes. These decreases of f(H 2 O) have been observed over the same time period in which a slow increase of SBUV NLC albedo has occurred. From this scenario and additional arguments we conclude that the cause for the observed long-term increase in NLC albedo remains to be identified. We close with comments on the very different character of decadal variations in NLC brightness and occurrence rate. Text albedo Arctic Copernicus Publications: E-Journals Alomar ENVELOPE(-67.083,-67.083,-68.133,-68.133) Arctic Atmospheric Chemistry and Physics 4 11/12 2449 2464 |
institution |
Open Polar |
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Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
The topic of this paper is the sensitivity of the brightness of noctilucent clouds (NLC) on the ambient water vapour mixing ratio f(H 2 O). Firstly, we use state-of-the-art models of NLC layer formation to predict NLC brightness changes in response to changes in the 80km mixing ratio f(H 2 O) for the two cases of ground-based 532nm lidar observations at 69° N and for hemispheric satellite SBUV observations at 252nm wavelength. In this study, we include a re-evaluation of the sensitivity of NLC brightness to changes in solar Lyman α flux. Secondly, we review observations of episodic changes in f(H 2 O) and those in NLC brightness, the former being available since 1992, the latter since 1979. To this review, we add a new series of observations of f(H 2 O), performed in the Arctic summer at the ALOMAR observatory. The episodic change exhibited by the Arctic summer means of f(H 2 O) turns out to be quite different from all those derived from annual means of f(H 2 O). The latter indicate that since 1996 a significant reduction of annually averaged upper mesospheric water vapour has occurred at low, mid, and high latitudes. These decreases of f(H 2 O) have been observed over the same time period in which a slow increase of SBUV NLC albedo has occurred. From this scenario and additional arguments we conclude that the cause for the observed long-term increase in NLC albedo remains to be identified. We close with comments on the very different character of decadal variations in NLC brightness and occurrence rate. |
format |
Text |
author |
Zahn, U. Baumgarten, G. Berger, U. Fiedler, J. Hartogh, P. |
spellingShingle |
Zahn, U. Baumgarten, G. Berger, U. Fiedler, J. Hartogh, P. Noctilucent clouds and the mesospheric water vapour: the past decade |
author_facet |
Zahn, U. Baumgarten, G. Berger, U. Fiedler, J. Hartogh, P. |
author_sort |
Zahn, U. |
title |
Noctilucent clouds and the mesospheric water vapour: the past decade |
title_short |
Noctilucent clouds and the mesospheric water vapour: the past decade |
title_full |
Noctilucent clouds and the mesospheric water vapour: the past decade |
title_fullStr |
Noctilucent clouds and the mesospheric water vapour: the past decade |
title_full_unstemmed |
Noctilucent clouds and the mesospheric water vapour: the past decade |
title_sort |
noctilucent clouds and the mesospheric water vapour: the past decade |
publishDate |
2018 |
url |
https://doi.org/10.5194/acp-4-2449-2004 https://www.atmos-chem-phys.net/4/2449/2004/ |
long_lat |
ENVELOPE(-67.083,-67.083,-68.133,-68.133) |
geographic |
Alomar Arctic |
geographic_facet |
Alomar Arctic |
genre |
albedo Arctic |
genre_facet |
albedo Arctic |
op_source |
eISSN: 1680-7324 |
op_relation |
doi:10.5194/acp-4-2449-2004 https://www.atmos-chem-phys.net/4/2449/2004/ |
op_doi |
https://doi.org/10.5194/acp-4-2449-2004 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
4 |
container_issue |
11/12 |
container_start_page |
2449 |
op_container_end_page |
2464 |
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1766247154519638016 |