Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR
From 1997 to 2003, noctilucent clouds (NLC) were observed by lidar above the ALOMAR observatory in Northern Norway (69° N) during a total of 1880measurement hours. This data set contains NLC signatures for 640h, covering all local times, even during the highest solar background conditions. After dat...
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ftcopernicus:oai:publications.copernicus.org:angeo35505 2023-05-15T17:43:31+02:00 Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR Fiedler, J. Baumgarten, G. Cossart, G. 2018-09-27 application/pdf https://doi.org/10.5194/angeo-23-1175-2005 https://angeo.copernicus.org/articles/23/1175/2005/ eng eng doi:10.5194/angeo-23-1175-2005 https://angeo.copernicus.org/articles/23/1175/2005/ eISSN: 1432-0576 Text 2018 ftcopernicus https://doi.org/10.5194/angeo-23-1175-2005 2020-07-20T16:27:25Z From 1997 to 2003, noctilucent clouds (NLC) were observed by lidar above the ALOMAR observatory in Northern Norway (69° N) during a total of 1880measurement hours. This data set contains NLC signatures for 640h, covering all local times, even during the highest solar background conditions. After data limitation imposing a threshold value of 4x10 -10 m -1 sr -1 for the volume backscatter coefficient of the NLC particles, a measure for the cloud brightness, local time dependencies of the NLC occurrence frequency, altitude, and brightness were determined. On average, over the 7years NLC occurred during the whole day and preferably in the early morning hours, with a maximum occurrence frequency of ~40% between 4 and 7LT. Splitting the data into weak and strong clouds yields almost identical amplitudes of diurnal and semidiurnal variations for the occurrence of weak clouds, whereas the strong clouds are dominated by the diurnal variation. NLC occurrence, altitude, as well as brightness, show a remarkable persistence concerning diurnal and semidiurnal variations from 1997 to 2003, suggesting that NLC above ALOMAR are significantly controlled by atmospheric tides. The observed mean anti-phase behavior between cloud altitude and brightness is attributed to a phase shift between the semidiurnal components by ~6h. Investigation of data for each individual year regarding the prevailing oscillation periods of the NLC parameters showed different phase relationships, leading to a complex variability in the cloud parameters. Text Northern Norway Copernicus Publications: E-Journals Alomar ENVELOPE(-67.083,-67.083,-68.133,-68.133) Norway Annales Geophysicae 23 4 1175 1181 |
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Open Polar |
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Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
From 1997 to 2003, noctilucent clouds (NLC) were observed by lidar above the ALOMAR observatory in Northern Norway (69° N) during a total of 1880measurement hours. This data set contains NLC signatures for 640h, covering all local times, even during the highest solar background conditions. After data limitation imposing a threshold value of 4x10 -10 m -1 sr -1 for the volume backscatter coefficient of the NLC particles, a measure for the cloud brightness, local time dependencies of the NLC occurrence frequency, altitude, and brightness were determined. On average, over the 7years NLC occurred during the whole day and preferably in the early morning hours, with a maximum occurrence frequency of ~40% between 4 and 7LT. Splitting the data into weak and strong clouds yields almost identical amplitudes of diurnal and semidiurnal variations for the occurrence of weak clouds, whereas the strong clouds are dominated by the diurnal variation. NLC occurrence, altitude, as well as brightness, show a remarkable persistence concerning diurnal and semidiurnal variations from 1997 to 2003, suggesting that NLC above ALOMAR are significantly controlled by atmospheric tides. The observed mean anti-phase behavior between cloud altitude and brightness is attributed to a phase shift between the semidiurnal components by ~6h. Investigation of data for each individual year regarding the prevailing oscillation periods of the NLC parameters showed different phase relationships, leading to a complex variability in the cloud parameters. |
format |
Text |
author |
Fiedler, J. Baumgarten, G. Cossart, G. |
spellingShingle |
Fiedler, J. Baumgarten, G. Cossart, G. Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR |
author_facet |
Fiedler, J. Baumgarten, G. Cossart, G. |
author_sort |
Fiedler, J. |
title |
Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR |
title_short |
Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR |
title_full |
Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR |
title_fullStr |
Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR |
title_full_unstemmed |
Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR |
title_sort |
mean diurnal variations of noctilucent clouds during 7 years of lidar observations at alomar |
publishDate |
2018 |
url |
https://doi.org/10.5194/angeo-23-1175-2005 https://angeo.copernicus.org/articles/23/1175/2005/ |
long_lat |
ENVELOPE(-67.083,-67.083,-68.133,-68.133) |
geographic |
Alomar Norway |
geographic_facet |
Alomar Norway |
genre |
Northern Norway |
genre_facet |
Northern Norway |
op_source |
eISSN: 1432-0576 |
op_relation |
doi:10.5194/angeo-23-1175-2005 https://angeo.copernicus.org/articles/23/1175/2005/ |
op_doi |
https://doi.org/10.5194/angeo-23-1175-2005 |
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Annales Geophysicae |
container_volume |
23 |
container_issue |
4 |
container_start_page |
1175 |
op_container_end_page |
1181 |
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1766145615649046528 |