Gravity waves and small-scale structure of the high-latitude upper atmosphere
Small-scale structure of the thermosphere is studied at high-latitudes for its important role in ion-neutral coupling. Four Fabry-Perot Interferometers (FPIs) in Scandinavia are primarily used. These are supplemented by a range of other instruments, including the Spectrograph Imaging Facility, radar...
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University of London
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ftucl:oai:eprints.ucl.ac.uk.OAI2:1445456 2023-12-24T10:16:18+01:00 Gravity waves and small-scale structure of the high-latitude upper atmosphere Ford, Elaina Anna Katrina 2007 text https://discovery.ucl.ac.uk/id/eprint/1445456/4/Ford_1445456_thesis.pdf https://discovery.ucl.ac.uk/id/eprint/1445456/ eng eng University of London https://discovery.ucl.ac.uk/id/eprint/1445456/4/Ford_1445456_thesis.pdf https://discovery.ucl.ac.uk/id/eprint/1445456/ open Doctoral thesis, University of London. Thesis Doctoral 2007 ftucl 2023-11-27T13:07:38Z Small-scale structure of the thermosphere is studied at high-latitudes for its important role in ion-neutral coupling. Four Fabry-Perot Interferometers (FPIs) in Scandinavia are primarily used. These are supplemented by a range of other instruments, including the Spectrograph Imaging Facility, radars, magnetometers, all-sky cameras, and satellite data. The FPIs measure the atomic oxygen emission line at 6300 A, from 240 km altitude. Emission intensities, thermospheric line of sight wind speeds, and neutral temperatures are obtained. Comparisons of electron densities from tomography data and EISCAT (European Incoherent SCATter) radar with FPI intensities allow the investigation whether dissociative recombination is the dominant production mechanisms of the nighttime 6300 A oxygen line. Cross correlations indicate that the thermosphere varies on short temporal scales. Altitude variations have less effect due to the broad (-50 km) emission height band. Atmospheric gravity waves in the thermosphere have been detected for the first time in ground-based FPI data using Lomb-Scargle analysis. Joule heating from electrojet currents, and particle precipitation in the auroral oval, have been identified as the primary source mechanisms using two case study nights. High time resolution data shows a limit to the variability of the thermosphere to be approximately 1-minute. Statistical studies of the gravity waves from 567 nights of FPI data show that the length of the night and time resolution are the most important influences on the number and periods of waves detected. Greater numbers of short period waves are detected in the rapidly responding intensities than in the winds and temperatures. Little variation with geomagnetic activity or solar cycle is observed. Periods at particular harmonics of the length of the night are preferred between October and February. Comparisons of mainland and Svalbard data show that the shorter period waves that are formed equatorward in the auroral oval mostly dissipate before reaching ... Doctoral or Postdoctoral Thesis EISCAT Svalbard University College London: UCL Discovery Svalbard |
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Open Polar |
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University College London: UCL Discovery |
op_collection_id |
ftucl |
language |
English |
description |
Small-scale structure of the thermosphere is studied at high-latitudes for its important role in ion-neutral coupling. Four Fabry-Perot Interferometers (FPIs) in Scandinavia are primarily used. These are supplemented by a range of other instruments, including the Spectrograph Imaging Facility, radars, magnetometers, all-sky cameras, and satellite data. The FPIs measure the atomic oxygen emission line at 6300 A, from 240 km altitude. Emission intensities, thermospheric line of sight wind speeds, and neutral temperatures are obtained. Comparisons of electron densities from tomography data and EISCAT (European Incoherent SCATter) radar with FPI intensities allow the investigation whether dissociative recombination is the dominant production mechanisms of the nighttime 6300 A oxygen line. Cross correlations indicate that the thermosphere varies on short temporal scales. Altitude variations have less effect due to the broad (-50 km) emission height band. Atmospheric gravity waves in the thermosphere have been detected for the first time in ground-based FPI data using Lomb-Scargle analysis. Joule heating from electrojet currents, and particle precipitation in the auroral oval, have been identified as the primary source mechanisms using two case study nights. High time resolution data shows a limit to the variability of the thermosphere to be approximately 1-minute. Statistical studies of the gravity waves from 567 nights of FPI data show that the length of the night and time resolution are the most important influences on the number and periods of waves detected. Greater numbers of short period waves are detected in the rapidly responding intensities than in the winds and temperatures. Little variation with geomagnetic activity or solar cycle is observed. Periods at particular harmonics of the length of the night are preferred between October and February. Comparisons of mainland and Svalbard data show that the shorter period waves that are formed equatorward in the auroral oval mostly dissipate before reaching ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Ford, Elaina Anna Katrina |
spellingShingle |
Ford, Elaina Anna Katrina Gravity waves and small-scale structure of the high-latitude upper atmosphere |
author_facet |
Ford, Elaina Anna Katrina |
author_sort |
Ford, Elaina Anna Katrina |
title |
Gravity waves and small-scale structure of the high-latitude upper atmosphere |
title_short |
Gravity waves and small-scale structure of the high-latitude upper atmosphere |
title_full |
Gravity waves and small-scale structure of the high-latitude upper atmosphere |
title_fullStr |
Gravity waves and small-scale structure of the high-latitude upper atmosphere |
title_full_unstemmed |
Gravity waves and small-scale structure of the high-latitude upper atmosphere |
title_sort |
gravity waves and small-scale structure of the high-latitude upper atmosphere |
publisher |
University of London |
publishDate |
2007 |
url |
https://discovery.ucl.ac.uk/id/eprint/1445456/4/Ford_1445456_thesis.pdf https://discovery.ucl.ac.uk/id/eprint/1445456/ |
geographic |
Svalbard |
geographic_facet |
Svalbard |
genre |
EISCAT Svalbard |
genre_facet |
EISCAT Svalbard |
op_source |
Doctoral thesis, University of London. |
op_relation |
https://discovery.ucl.ac.uk/id/eprint/1445456/4/Ford_1445456_thesis.pdf https://discovery.ucl.ac.uk/id/eprint/1445456/ |
op_rights |
open |
_version_ |
1786203719498465280 |