VHF radar observations of turbulent structures in the polar mesopause region
The mobile SOUSY VHF Radar was operated in the summer of 1987 during the MAC/SINE campaign in northern Norway to study the polar mesosphere summer echoes (PMSE). Measurements of the spectral width indicate that two types of structures occur. In general mesospheric layers are bifurcated exhibiting a...
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ftdoajarticles:oai:doaj.org/article:8dfe52419e9d43feb76b332cfb5bee0e 2023-05-15T17:43:36+02:00 VHF radar observations of turbulent structures in the polar mesopause region P. Czechowsky R. Rüster 1997-08-01T00:00:00Z https://doi.org/10.1007/s00585-997-1028-8 https://doaj.org/article/8dfe52419e9d43feb76b332cfb5bee0e EN eng Copernicus Publications https://www.ann-geophys.net/15/1028/1997/angeo-15-1028-1997.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-997-1028-8 0992-7689 1432-0576 https://doaj.org/article/8dfe52419e9d43feb76b332cfb5bee0e Annales Geophysicae, Vol 15, Pp 1028-1036 (1997) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 1997 ftdoajarticles https://doi.org/10.1007/s00585-997-1028-8 2022-12-31T13:42:53Z The mobile SOUSY VHF Radar was operated in the summer of 1987 during the MAC/SINE campaign in northern Norway to study the polar mesosphere summer echoes (PMSE). Measurements of the spectral width indicate that two types of structures occur. In general mesospheric layers are bifurcated exhibiting a narrow spectral width and a well-defined aspect sensitivity. However, for about 10% of the observation time cells of enhanced turbulence characterized by extremely broad spectral widths appear predominantly in the upper sublayer above 86 km. Identification and separation of beam and shear broadening allows a determination of the turbulence-induced component of the spectral width. This case study reveals that during several events these cloud-like structures of enhanced turbulence move with an apparent velocity of several tens of meters per second which is almost identical with the phase trace velocity of simultaneously observed waves. Since, at that time, the Richardson number was less than a quarter, it was concluded that these turbulent cells were generated by a Kelvin-Helmholtz mechanism. The horizontal extent of these structures was calculated to be less than 40 km. A general relation between spectral width and echo power was not detected. The turbulent component of the spectral width was used to calculate typical values of the energy dissipation rate at times where narrow spectral width dominates and during periods of enhanced turbulence. In addition, the outer scale of the inertial subrange (buoyancy scale) was estimated. For the first time the occurrence and motion of this type of structures of enhanced spectral width is analyzed and discussed in detail. Article in Journal/Newspaper Northern Norway Directory of Open Access Journals: DOAJ Articles Norway Annales Geophysicae 15 8 1028 1036 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
spellingShingle |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 P. Czechowsky R. Rüster VHF radar observations of turbulent structures in the polar mesopause region |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
The mobile SOUSY VHF Radar was operated in the summer of 1987 during the MAC/SINE campaign in northern Norway to study the polar mesosphere summer echoes (PMSE). Measurements of the spectral width indicate that two types of structures occur. In general mesospheric layers are bifurcated exhibiting a narrow spectral width and a well-defined aspect sensitivity. However, for about 10% of the observation time cells of enhanced turbulence characterized by extremely broad spectral widths appear predominantly in the upper sublayer above 86 km. Identification and separation of beam and shear broadening allows a determination of the turbulence-induced component of the spectral width. This case study reveals that during several events these cloud-like structures of enhanced turbulence move with an apparent velocity of several tens of meters per second which is almost identical with the phase trace velocity of simultaneously observed waves. Since, at that time, the Richardson number was less than a quarter, it was concluded that these turbulent cells were generated by a Kelvin-Helmholtz mechanism. The horizontal extent of these structures was calculated to be less than 40 km. A general relation between spectral width and echo power was not detected. The turbulent component of the spectral width was used to calculate typical values of the energy dissipation rate at times where narrow spectral width dominates and during periods of enhanced turbulence. In addition, the outer scale of the inertial subrange (buoyancy scale) was estimated. For the first time the occurrence and motion of this type of structures of enhanced spectral width is analyzed and discussed in detail. |
format |
Article in Journal/Newspaper |
author |
P. Czechowsky R. Rüster |
author_facet |
P. Czechowsky R. Rüster |
author_sort |
P. Czechowsky |
title |
VHF radar observations of turbulent structures in the polar mesopause region |
title_short |
VHF radar observations of turbulent structures in the polar mesopause region |
title_full |
VHF radar observations of turbulent structures in the polar mesopause region |
title_fullStr |
VHF radar observations of turbulent structures in the polar mesopause region |
title_full_unstemmed |
VHF radar observations of turbulent structures in the polar mesopause region |
title_sort |
vhf radar observations of turbulent structures in the polar mesopause region |
publisher |
Copernicus Publications |
publishDate |
1997 |
url |
https://doi.org/10.1007/s00585-997-1028-8 https://doaj.org/article/8dfe52419e9d43feb76b332cfb5bee0e |
geographic |
Norway |
geographic_facet |
Norway |
genre |
Northern Norway |
genre_facet |
Northern Norway |
op_source |
Annales Geophysicae, Vol 15, Pp 1028-1036 (1997) |
op_relation |
https://www.ann-geophys.net/15/1028/1997/angeo-15-1028-1997.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-997-1028-8 0992-7689 1432-0576 https://doaj.org/article/8dfe52419e9d43feb76b332cfb5bee0e |
op_doi |
https://doi.org/10.1007/s00585-997-1028-8 |
container_title |
Annales Geophysicae |
container_volume |
15 |
container_issue |
8 |
container_start_page |
1028 |
op_container_end_page |
1036 |
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1766145715600359424 |