Stratospheric gravity waves over the mountainous island of South Georgia: testing a high-resolution dynamical model with 3-D satellite observations and radiosondes
Atmospheric gravity waves (GWs) play an important role in atmospheric dynamics but accurately representing them in general circulation models (GCMs) is challenging. This is especially true for orographic GWs generated by wind flow over small mountainous islands in the Southern Ocean. Currently, thes...
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2021
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ftdoajarticles:oai:doaj.org/article:d92d67831986471e8562b37423392847 2023-05-15T18:25:58+02:00 Stratospheric gravity waves over the mountainous island of South Georgia: testing a high-resolution dynamical model with 3-D satellite observations and radiosondes N. P. Hindley C. J. Wright A. M. Gadian L. Hoffmann J. K. Hughes D. R. Jackson J. C. King N. J. Mitchell T. Moffat-Griffin A. C. Moss S. B. Vosper A. N. Ross 2021-05-01T00:00:00Z https://doi.org/10.5194/acp-21-7695-2021 https://doaj.org/article/d92d67831986471e8562b37423392847 EN eng Copernicus Publications https://acp.copernicus.org/articles/21/7695/2021/acp-21-7695-2021.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 doi:10.5194/acp-21-7695-2021 1680-7316 1680-7324 https://doaj.org/article/d92d67831986471e8562b37423392847 Atmospheric Chemistry and Physics, Vol 21, Pp 7695-7722 (2021) Physics QC1-999 Chemistry QD1-999 article 2021 ftdoajarticles https://doi.org/10.5194/acp-21-7695-2021 2022-12-31T15:48:38Z Atmospheric gravity waves (GWs) play an important role in atmospheric dynamics but accurately representing them in general circulation models (GCMs) is challenging. This is especially true for orographic GWs generated by wind flow over small mountainous islands in the Southern Ocean. Currently, these islands lie in the “grey zone” of global model resolution, where they are neither fully resolved nor fully parameterised. It is expected that as GCMs approach the spatial resolution of current high-resolution local-area models, small-island GW sources may be resolved without the need for parameterisations. But how realistic are the resolved GWs in these high-resolution simulations compared to observations? Here, we test a high-resolution (1.5 km horizontal grid, 118 vertical levels) local-area configuration of the Met Office Unified Model over the mountainous island of South Georgia (54 ∘ S, 36 ∘ W), running without GW parameterisations. The island's orography is well resolved in the model, and real-time boundary conditions are used for two time periods during July 2013 and June–July 2015. We compare simulated GWs in the model to coincident 3-D satellite observations from the Atmospheric Infrared Sounder (AIRS) on board Aqua. By carefully sampling the model using the AIRS resolution and measurement footprints (denoted as model sampled as AIRS hereafter), we present the first like-for-like comparison of simulated and observed 3-D GW amplitudes, wavelengths and directional GW momentum flux (GWMF) over the island using a 3-D S -transform method. We find that the timing, magnitude and direction of simulated GWMF over South Georgia are in good general agreement with observations, once the AIRS sampling and resolution are applied to the model. Area-averaged zonal GWMF during these 2 months is westward at around 5.3 and 5.6 mPa in AIRS and model sampled as AIRS datasets respectively, but values directly over the island can exceed 50 mPa. However, up to 35 % of the total GWMF in AIRS is actually found upwind of the island ... Article in Journal/Newspaper Southern Ocean Directory of Open Access Journals: DOAJ Articles Southern Ocean Atmospheric Chemistry and Physics 21 10 7695 7722 |
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Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Physics QC1-999 Chemistry QD1-999 |
spellingShingle |
Physics QC1-999 Chemistry QD1-999 N. P. Hindley C. J. Wright A. M. Gadian L. Hoffmann J. K. Hughes D. R. Jackson J. C. King N. J. Mitchell T. Moffat-Griffin A. C. Moss S. B. Vosper A. N. Ross Stratospheric gravity waves over the mountainous island of South Georgia: testing a high-resolution dynamical model with 3-D satellite observations and radiosondes |
topic_facet |
Physics QC1-999 Chemistry QD1-999 |
description |
Atmospheric gravity waves (GWs) play an important role in atmospheric dynamics but accurately representing them in general circulation models (GCMs) is challenging. This is especially true for orographic GWs generated by wind flow over small mountainous islands in the Southern Ocean. Currently, these islands lie in the “grey zone” of global model resolution, where they are neither fully resolved nor fully parameterised. It is expected that as GCMs approach the spatial resolution of current high-resolution local-area models, small-island GW sources may be resolved without the need for parameterisations. But how realistic are the resolved GWs in these high-resolution simulations compared to observations? Here, we test a high-resolution (1.5 km horizontal grid, 118 vertical levels) local-area configuration of the Met Office Unified Model over the mountainous island of South Georgia (54 ∘ S, 36 ∘ W), running without GW parameterisations. The island's orography is well resolved in the model, and real-time boundary conditions are used for two time periods during July 2013 and June–July 2015. We compare simulated GWs in the model to coincident 3-D satellite observations from the Atmospheric Infrared Sounder (AIRS) on board Aqua. By carefully sampling the model using the AIRS resolution and measurement footprints (denoted as model sampled as AIRS hereafter), we present the first like-for-like comparison of simulated and observed 3-D GW amplitudes, wavelengths and directional GW momentum flux (GWMF) over the island using a 3-D S -transform method. We find that the timing, magnitude and direction of simulated GWMF over South Georgia are in good general agreement with observations, once the AIRS sampling and resolution are applied to the model. Area-averaged zonal GWMF during these 2 months is westward at around 5.3 and 5.6 mPa in AIRS and model sampled as AIRS datasets respectively, but values directly over the island can exceed 50 mPa. However, up to 35 % of the total GWMF in AIRS is actually found upwind of the island ... |
format |
Article in Journal/Newspaper |
author |
N. P. Hindley C. J. Wright A. M. Gadian L. Hoffmann J. K. Hughes D. R. Jackson J. C. King N. J. Mitchell T. Moffat-Griffin A. C. Moss S. B. Vosper A. N. Ross |
author_facet |
N. P. Hindley C. J. Wright A. M. Gadian L. Hoffmann J. K. Hughes D. R. Jackson J. C. King N. J. Mitchell T. Moffat-Griffin A. C. Moss S. B. Vosper A. N. Ross |
author_sort |
N. P. Hindley |
title |
Stratospheric gravity waves over the mountainous island of South Georgia: testing a high-resolution dynamical model with 3-D satellite observations and radiosondes |
title_short |
Stratospheric gravity waves over the mountainous island of South Georgia: testing a high-resolution dynamical model with 3-D satellite observations and radiosondes |
title_full |
Stratospheric gravity waves over the mountainous island of South Georgia: testing a high-resolution dynamical model with 3-D satellite observations and radiosondes |
title_fullStr |
Stratospheric gravity waves over the mountainous island of South Georgia: testing a high-resolution dynamical model with 3-D satellite observations and radiosondes |
title_full_unstemmed |
Stratospheric gravity waves over the mountainous island of South Georgia: testing a high-resolution dynamical model with 3-D satellite observations and radiosondes |
title_sort |
stratospheric gravity waves over the mountainous island of south georgia: testing a high-resolution dynamical model with 3-d satellite observations and radiosondes |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/acp-21-7695-2021 https://doaj.org/article/d92d67831986471e8562b37423392847 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Atmospheric Chemistry and Physics, Vol 21, Pp 7695-7722 (2021) |
op_relation |
https://acp.copernicus.org/articles/21/7695/2021/acp-21-7695-2021.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 doi:10.5194/acp-21-7695-2021 1680-7316 1680-7324 https://doaj.org/article/d92d67831986471e8562b37423392847 |
op_doi |
https://doi.org/10.5194/acp-21-7695-2021 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
21 |
container_issue |
10 |
container_start_page |
7695 |
op_container_end_page |
7722 |
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1766207706851442688 |