Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54° S, 36° W) and comparison with WACCM simulations
The mesosphere and lower thermosphere (MLT) is a dynamic layer of the earth’s atmosphere. This region marks the interface at which neutral atmosphere dynamics begin to influence the ionosphere and space weather. However, our understanding of this region and our ability to accurately simulate it in g...
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Format: | Article in Journal/Newspaper |
Language: | English |
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European Geosciences Union
2022
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Online Access: | http://nora.nerc.ac.uk/id/eprint/531564/ https://nora.nerc.ac.uk/id/eprint/531564/1/acp-22-9435-2022.pdf https://acp.copernicus.org/articles/22/9435/2022/ |
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ftnerc:oai:nora.nerc.ac.uk:531564 2023-05-15T18:21:30+02:00 Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54° S, 36° W) and comparison with WACCM simulations Hindley, Neil P. Cobbett, Neil Fritts, David C. Janchez, Diego Mitchell, Nicholas J. Moffat-Griffin, Tracy Smith, Anne K. Wright, Corwin J. 2022-07-22 text http://nora.nerc.ac.uk/id/eprint/531564/ https://nora.nerc.ac.uk/id/eprint/531564/1/acp-22-9435-2022.pdf https://acp.copernicus.org/articles/22/9435/2022/ en eng European Geosciences Union https://nora.nerc.ac.uk/id/eprint/531564/1/acp-22-9435-2022.pdf Hindley, Neil P.; Cobbett, Neil; Fritts, David C.; Janchez, Diego; Mitchell, Nicholas J.; Moffat-Griffin, Tracy orcid:0000-0002-9670-6715 Smith, Anne K.; Wright, Corwin J. 2022 Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54° S, 36° W) and comparison with WACCM simulations. Atmospheric Chemistry and Physics, 22 (14). 9435-9459. https://doi.org/10.5194/acp-22-9435-2022 <https://doi.org/10.5194/acp-22-9435-2022> cc_by_4 CC-BY Publication - Article PeerReviewed 2022 ftnerc https://doi.org/10.5194/acp-22-9435-2022 2023-02-04T19:52:47Z The mesosphere and lower thermosphere (MLT) is a dynamic layer of the earth’s atmosphere. This region marks the interface at which neutral atmosphere dynamics begin to influence the ionosphere and space weather. However, our understanding of this region and our ability to accurately simulate it in global circulation models (GCMs) is limited by a lack of observations, especially in remote locations. To this end, a meteor radar was deployed on the remote mountainous island of South Georgia (54° S, 36° W) in the Southern Ocean from 2016 to 2020. The goal of this study is to use these new measurements to characterise the fundamental dynamics of the MLT above South Georgia including large-scale winds, solar tides, planetary waves (PWs) and mesoscale gravity waves (GWs). We first present an improved method for time-height localisation of radar wind measurements and characterise the large-scale MLT winds. We then explore the amplitudes and phases of the diurnal (24 h), semidiurnal (12 h) and terdiurnal (8 h) solar tides at this latitude. We also explore PW activity and find very large amplitudes up to 30 ms−1 for the quasi-2 day wave in summer and show that the dominant modes of the quasi-5, 10 and 16 day waves are westward W1 and W2. We investigate wind variance due to GWs in the MLT and use a new method to show an east-west tendency of GW variance of up to 20 % during summer and a weaker north-south tendency of 0–5 % during winter. This is contrary to the expected tendency of GW directions in the winter stratosphere below, which is a strong suggestion of secondary GW (2GW) observations in the MLT. Lastly, comparison of radar winds to a climatological Whole Atmosphere Community Climate Model (WACCM) simulation reveals a simulated summertime mesopause and zonal wind shear that occur at altitudes around 10 km lower than observed, and southward winds during winter above 90 km altitude in the model that are not seen in observations. Further, wintertime zonal winds above 85 km altitude are eastward in radar observations ... Article in Journal/Newspaper South Georgia Island Southern Ocean Natural Environment Research Council: NERC Open Research Archive South Georgia Island ENVELOPE(-36.750,-36.750,-54.250,-54.250) Southern Ocean Atmospheric Chemistry and Physics 22 14 9435 9459 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
description |
The mesosphere and lower thermosphere (MLT) is a dynamic layer of the earth’s atmosphere. This region marks the interface at which neutral atmosphere dynamics begin to influence the ionosphere and space weather. However, our understanding of this region and our ability to accurately simulate it in global circulation models (GCMs) is limited by a lack of observations, especially in remote locations. To this end, a meteor radar was deployed on the remote mountainous island of South Georgia (54° S, 36° W) in the Southern Ocean from 2016 to 2020. The goal of this study is to use these new measurements to characterise the fundamental dynamics of the MLT above South Georgia including large-scale winds, solar tides, planetary waves (PWs) and mesoscale gravity waves (GWs). We first present an improved method for time-height localisation of radar wind measurements and characterise the large-scale MLT winds. We then explore the amplitudes and phases of the diurnal (24 h), semidiurnal (12 h) and terdiurnal (8 h) solar tides at this latitude. We also explore PW activity and find very large amplitudes up to 30 ms−1 for the quasi-2 day wave in summer and show that the dominant modes of the quasi-5, 10 and 16 day waves are westward W1 and W2. We investigate wind variance due to GWs in the MLT and use a new method to show an east-west tendency of GW variance of up to 20 % during summer and a weaker north-south tendency of 0–5 % during winter. This is contrary to the expected tendency of GW directions in the winter stratosphere below, which is a strong suggestion of secondary GW (2GW) observations in the MLT. Lastly, comparison of radar winds to a climatological Whole Atmosphere Community Climate Model (WACCM) simulation reveals a simulated summertime mesopause and zonal wind shear that occur at altitudes around 10 km lower than observed, and southward winds during winter above 90 km altitude in the model that are not seen in observations. Further, wintertime zonal winds above 85 km altitude are eastward in radar observations ... |
format |
Article in Journal/Newspaper |
author |
Hindley, Neil P. Cobbett, Neil Fritts, David C. Janchez, Diego Mitchell, Nicholas J. Moffat-Griffin, Tracy Smith, Anne K. Wright, Corwin J. |
spellingShingle |
Hindley, Neil P. Cobbett, Neil Fritts, David C. Janchez, Diego Mitchell, Nicholas J. Moffat-Griffin, Tracy Smith, Anne K. Wright, Corwin J. Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54° S, 36° W) and comparison with WACCM simulations |
author_facet |
Hindley, Neil P. Cobbett, Neil Fritts, David C. Janchez, Diego Mitchell, Nicholas J. Moffat-Griffin, Tracy Smith, Anne K. Wright, Corwin J. |
author_sort |
Hindley, Neil P. |
title |
Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54° S, 36° W) and comparison with WACCM simulations |
title_short |
Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54° S, 36° W) and comparison with WACCM simulations |
title_full |
Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54° S, 36° W) and comparison with WACCM simulations |
title_fullStr |
Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54° S, 36° W) and comparison with WACCM simulations |
title_full_unstemmed |
Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54° S, 36° W) and comparison with WACCM simulations |
title_sort |
radar observations of winds, waves and tides in the mesosphere and lower thermosphere over south georgia island (54° s, 36° w) and comparison with waccm simulations |
publisher |
European Geosciences Union |
publishDate |
2022 |
url |
http://nora.nerc.ac.uk/id/eprint/531564/ https://nora.nerc.ac.uk/id/eprint/531564/1/acp-22-9435-2022.pdf https://acp.copernicus.org/articles/22/9435/2022/ |
long_lat |
ENVELOPE(-36.750,-36.750,-54.250,-54.250) |
geographic |
South Georgia Island Southern Ocean |
geographic_facet |
South Georgia Island Southern Ocean |
genre |
South Georgia Island Southern Ocean |
genre_facet |
South Georgia Island Southern Ocean |
op_relation |
https://nora.nerc.ac.uk/id/eprint/531564/1/acp-22-9435-2022.pdf Hindley, Neil P.; Cobbett, Neil; Fritts, David C.; Janchez, Diego; Mitchell, Nicholas J.; Moffat-Griffin, Tracy orcid:0000-0002-9670-6715 Smith, Anne K.; Wright, Corwin J. 2022 Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54° S, 36° W) and comparison with WACCM simulations. Atmospheric Chemistry and Physics, 22 (14). 9435-9459. https://doi.org/10.5194/acp-22-9435-2022 <https://doi.org/10.5194/acp-22-9435-2022> |
op_rights |
cc_by_4 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/acp-22-9435-2022 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
22 |
container_issue |
14 |
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9435 |
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9459 |
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1766200792510889984 |