Polar middle atmosphere dynamics
The dynamics of the polar mesosphere and lower thermosphere ( MLT ) is investigated using MF radars at Davis ( 69 ° S, 78 ° E ), Syowa ( 69 ° S, 40 ° E ) and Rothera ( 68 ° S, 68 ° W ) in the Antarctic, and Poker Flat ( 65 ° N, 147 ° W ) and Andenes ( 69 ° N, 16 ° E ) in the Arctic. Mean winds and g...
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ftunivadelaidedl:oai:digital.library.adelaide.edu.au:2440/38004 2023-05-15T13:25:24+02:00 Polar middle atmosphere dynamics Dowdy, Andrew J. Reid, Iain Murray Vincent, Bob School of Chemistry and Physics 2005 2432329 bytes 2844472 bytes 2694803 bytes 1600289 bytes 70684 bytes application/pdf http://hdl.handle.net/2440/38004 en eng http://hdl.handle.net/2440/38004 meteorology and atmospheric dynamics atmosphere observations polar regions Antartica Artic regions Thesis 2005 ftunivadelaidedl 2023-02-05T19:28:35Z The dynamics of the polar mesosphere and lower thermosphere ( MLT ) is investigated using MF radars at Davis ( 69 ° S, 78 ° E ), Syowa ( 69 ° S, 40 ° E ) and Rothera ( 68 ° S, 68 ° W ) in the Antarctic, and Poker Flat ( 65 ° N, 147 ° W ) and Andenes ( 69 ° N, 16 ° E ) in the Arctic. Mean winds and gravity waves are investigated on a climatological scale and also during sudden stratospheric warmings. Mean wind climatologies in the MLT show differences that are often hemispheric in nature. For example, summer peaks in westward and equatorward winds occur earlier ( closer to the solstice ) in the Antarctic than in the Arctic. The greater symmetry around the solstice of phenomena such as these indicates that radiative effects may play a greater role in controlling the state of the Antarctic MLT than in the Arctic, where dynamical effects might be more important. Gravity wave observations are consistent with this theory, suggesting more wave drag may occur in the Arctic MLT. The equatorward jet persists for about 2 weeks later in summer in the Arctic than in the Antarctic, as do satellite observations of polar mesospheric clouds ( PMCs ) ( a temperature dependent phenomenon ). It is proposed that the meridional winds can be used as a proxy for gravity wave driving and consequent adiabatic cooling in the MLT. VHF radar observations of polar mesospheric summer echoes ( PMSEs ) at Davis, and the satellite PMC observations, both occur at a similar time to the equatorward jet. Seasonal variations in gravity wave activity are generally a combination of annual ( with winter maxima and summer minima ) and semi - annual ( with maxima near the solstices and minima near the equinoxes ) components. The winter maxima and spring / summer minima both occur about 3 weeks later in the Antarctic than in the Arctic, with the difference in magnitude between these extrema being about 90 % larger in the Antarctic. The available MF radar data include six major sudden stratospheric warmings in the northern hemisphere, and the unprecedented ... Thesis Andenes Antarc* Antarctic antartic* Arctic The University of Adelaide: Digital Library Antarctic Arctic Rothera ENVELOPE(-68.130,-68.130,-67.568,-67.568) The Antarctic |
institution |
Open Polar |
collection |
The University of Adelaide: Digital Library |
op_collection_id |
ftunivadelaidedl |
language |
English |
topic |
meteorology and atmospheric dynamics atmosphere observations polar regions Antartica Artic regions |
spellingShingle |
meteorology and atmospheric dynamics atmosphere observations polar regions Antartica Artic regions Dowdy, Andrew J. Polar middle atmosphere dynamics |
topic_facet |
meteorology and atmospheric dynamics atmosphere observations polar regions Antartica Artic regions |
description |
The dynamics of the polar mesosphere and lower thermosphere ( MLT ) is investigated using MF radars at Davis ( 69 ° S, 78 ° E ), Syowa ( 69 ° S, 40 ° E ) and Rothera ( 68 ° S, 68 ° W ) in the Antarctic, and Poker Flat ( 65 ° N, 147 ° W ) and Andenes ( 69 ° N, 16 ° E ) in the Arctic. Mean winds and gravity waves are investigated on a climatological scale and also during sudden stratospheric warmings. Mean wind climatologies in the MLT show differences that are often hemispheric in nature. For example, summer peaks in westward and equatorward winds occur earlier ( closer to the solstice ) in the Antarctic than in the Arctic. The greater symmetry around the solstice of phenomena such as these indicates that radiative effects may play a greater role in controlling the state of the Antarctic MLT than in the Arctic, where dynamical effects might be more important. Gravity wave observations are consistent with this theory, suggesting more wave drag may occur in the Arctic MLT. The equatorward jet persists for about 2 weeks later in summer in the Arctic than in the Antarctic, as do satellite observations of polar mesospheric clouds ( PMCs ) ( a temperature dependent phenomenon ). It is proposed that the meridional winds can be used as a proxy for gravity wave driving and consequent adiabatic cooling in the MLT. VHF radar observations of polar mesospheric summer echoes ( PMSEs ) at Davis, and the satellite PMC observations, both occur at a similar time to the equatorward jet. Seasonal variations in gravity wave activity are generally a combination of annual ( with winter maxima and summer minima ) and semi - annual ( with maxima near the solstices and minima near the equinoxes ) components. The winter maxima and spring / summer minima both occur about 3 weeks later in the Antarctic than in the Arctic, with the difference in magnitude between these extrema being about 90 % larger in the Antarctic. The available MF radar data include six major sudden stratospheric warmings in the northern hemisphere, and the unprecedented ... |
author2 |
Reid, Iain Murray Vincent, Bob School of Chemistry and Physics |
format |
Thesis |
author |
Dowdy, Andrew J. |
author_facet |
Dowdy, Andrew J. |
author_sort |
Dowdy, Andrew J. |
title |
Polar middle atmosphere dynamics |
title_short |
Polar middle atmosphere dynamics |
title_full |
Polar middle atmosphere dynamics |
title_fullStr |
Polar middle atmosphere dynamics |
title_full_unstemmed |
Polar middle atmosphere dynamics |
title_sort |
polar middle atmosphere dynamics |
publishDate |
2005 |
url |
http://hdl.handle.net/2440/38004 |
long_lat |
ENVELOPE(-68.130,-68.130,-67.568,-67.568) |
geographic |
Antarctic Arctic Rothera The Antarctic |
geographic_facet |
Antarctic Arctic Rothera The Antarctic |
genre |
Andenes Antarc* Antarctic antartic* Arctic |
genre_facet |
Andenes Antarc* Antarctic antartic* Arctic |
op_relation |
http://hdl.handle.net/2440/38004 |
_version_ |
1766385118589485056 |