Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar
The EISCAT VHF radar (69.4°N, 19.1°E) has been used to record vertical winds at mesopause heights on a total of 31 days between June 1990 and January 1993. The data reveal a motion field dominated by quasi-monochromatic gravity waves with representative apparent periods of ~30–40 min, amplitudes of...
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ftdoajarticles:oai:doaj.org/article:f7634e3f5de54d10ab0beb147ac21b94 2023-05-15T16:04:37+02:00 Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar N. J. Mitchell V. St. C. Howells 1998-10-01T00:00:00Z https://doi.org/10.1007/s00585-998-1367-0 https://doaj.org/article/f7634e3f5de54d10ab0beb147ac21b94 EN eng Copernicus Publications https://www.ann-geophys.net/16/1367/1998/angeo-16-1367-1998.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-998-1367-0 0992-7689 1432-0576 https://doaj.org/article/f7634e3f5de54d10ab0beb147ac21b94 Annales Geophysicae, Vol 16, Pp 1367-1379 (1998) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 1998 ftdoajarticles https://doi.org/10.1007/s00585-998-1367-0 2022-12-31T14:44:43Z The EISCAT VHF radar (69.4°N, 19.1°E) has been used to record vertical winds at mesopause heights on a total of 31 days between June 1990 and January 1993. The data reveal a motion field dominated by quasi-monochromatic gravity waves with representative apparent periods of ~30–40 min, amplitudes of up to ~2.5 m s –1 and large vertical wavelength. In some instances waves appear to be ducted. Vertical profiles of the vertical-velocity variance display a variety of forms, with little indication of systematic wave growth with height. Daily mean variance profiles evaluated for consecutive days of recording show that the general shape of the variance profiles persists over several days. The mean variance evaluated over a 10 km height range has values from 1.2 m 2 s –2 to 6.5 m 2 s –2 and suggests a semi-annual seasonal cycle with equinoctial minima and solsticial maxima. The mean vertical wavenumber spectrum evaluated at heights up to 86 km has a slope (spectral index) of –1.36 ± 0.2, consistent with observations at lower heights but disagreeing with the predictions of a number of saturation theories advanced to explain gravity-wave spectra. The spectral slopes evaluated for individual days have a range of values, and steeper slopes are observed in summer than in winter. The spectra also appear to be generally steeper on days with lower mean vertical-velocity variance. Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides) Article in Journal/Newspaper EISCAT Directory of Open Access Journals: DOAJ Articles Annales Geophysicae 16 10 1367 1379 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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English |
topic |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
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Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 N. J. Mitchell V. St. C. Howells Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
The EISCAT VHF radar (69.4°N, 19.1°E) has been used to record vertical winds at mesopause heights on a total of 31 days between June 1990 and January 1993. The data reveal a motion field dominated by quasi-monochromatic gravity waves with representative apparent periods of ~30–40 min, amplitudes of up to ~2.5 m s –1 and large vertical wavelength. In some instances waves appear to be ducted. Vertical profiles of the vertical-velocity variance display a variety of forms, with little indication of systematic wave growth with height. Daily mean variance profiles evaluated for consecutive days of recording show that the general shape of the variance profiles persists over several days. The mean variance evaluated over a 10 km height range has values from 1.2 m 2 s –2 to 6.5 m 2 s –2 and suggests a semi-annual seasonal cycle with equinoctial minima and solsticial maxima. The mean vertical wavenumber spectrum evaluated at heights up to 86 km has a slope (spectral index) of –1.36 ± 0.2, consistent with observations at lower heights but disagreeing with the predictions of a number of saturation theories advanced to explain gravity-wave spectra. The spectral slopes evaluated for individual days have a range of values, and steeper slopes are observed in summer than in winter. The spectra also appear to be generally steeper on days with lower mean vertical-velocity variance. Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides) |
format |
Article in Journal/Newspaper |
author |
N. J. Mitchell V. St. C. Howells |
author_facet |
N. J. Mitchell V. St. C. Howells |
author_sort |
N. J. Mitchell |
title |
Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar |
title_short |
Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar |
title_full |
Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar |
title_fullStr |
Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar |
title_full_unstemmed |
Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar |
title_sort |
vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the eiscat vhf radar |
publisher |
Copernicus Publications |
publishDate |
1998 |
url |
https://doi.org/10.1007/s00585-998-1367-0 https://doaj.org/article/f7634e3f5de54d10ab0beb147ac21b94 |
genre |
EISCAT |
genre_facet |
EISCAT |
op_source |
Annales Geophysicae, Vol 16, Pp 1367-1379 (1998) |
op_relation |
https://www.ann-geophys.net/16/1367/1998/angeo-16-1367-1998.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.1007/s00585-998-1367-0 0992-7689 1432-0576 https://doaj.org/article/f7634e3f5de54d10ab0beb147ac21b94 |
op_doi |
https://doi.org/10.1007/s00585-998-1367-0 |
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Annales Geophysicae |
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16 |
container_issue |
10 |
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1367 |
op_container_end_page |
1379 |
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1766400213032894464 |