A new mechanism for spontaneous imbalance exciting large-area gravity waves
In order to improve global atmospheric modelling, the trend is towards including source-specific gravity waves (GWs) in general circulation models. In a case study, we search for the source of a GW observed over Greenland on 10 March 2016 using the Gimballed Limb Observer for Radiance Imaging of the...
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ftfzjuelichnvdb:oai:juser.fz-juelich.de:892383 2024-09-15T18:09:18+00:00 A new mechanism for spontaneous imbalance exciting large-area gravity waves Geldenhuys, Markus Preusse, Peter Krisch, Isabell Zuelicke, Christoph Ungermann, Jörn Ern, Manfred Friedl-Vallon, Felix Riese, Martin DE 2021 https://juser.fz-juelich.de/record/892383 https://juser.fz-juelich.de/search?p=id:%22FZJ-2021-02044%22 eng eng info:eu-repo/semantics/altIdentifier/doi/10.5194/egusphere-egu21-5591 https://juser.fz-juelich.de/record/892383 https://juser.fz-juelich.de/search?p=id:%22FZJ-2021-02044%22 info:eu-repo/semantics/closedAccess doi:10.5194/egusphere-egu21-5591 European Geoscience Union 2021, EGU21, Online, Online, 2021-04-19 - 2021-04-30 info:eu-repo/semantics/conferenceObject info:eu-repo/semantics/publishedVersion 2021 ftfzjuelichnvdb https://doi.org/10.5194/egusphere-egu21-5591 2024-08-05T23:55:47Z In order to improve global atmospheric modelling, the trend is towards including source-specific gravity waves (GWs) in general circulation models. In a case study, we search for the source of a GW observed over Greenland on 10 March 2016 using the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) onboard the German research aircraft HALO. GLORIA is a remote sensing instrument where the measured infrared radiances are converted into a 3D temperature field through tomography. We observe a GW packet between 10 and 13km that covers ∼1/3 of the Greenland mainland. GLORIA observations indicate a horizontal (vertical) wavelength of 330km (2km) and a temperature amplitude of 4.5K. Slanted phase fronts indicate intrinsic propagation against the jet but the GW packet propagates (ground-based) with the wind. To find the GW source, 3D GLORIA observations, GROGRAT raytracer, ERA5 data, and an ECMWF numerical experiment are used. The numerical experiment with a smoothed topography indicates virtually no GWs suggesting that the GW field in the full model is caused by the orography. However, these are not mountain waves. A favourable area for spontaneous GW emission is identified within the jet exit region by the cross-stream ageostrophic wind speed, which indicates when the flow is not in geostrophic balance. Backtracing experiments (using GROGRAT) trace into the jet and imbalance regions. The difference between the full and the smooth-topography experiment is the change in wind components by the compression of air above Greenland. These accelerations and decelerations in the jet cause the jet to become out of geostrophic balance, which excites GWs by spontaneous adjustment. We present, to the best of our knowledge, the first observational evidence of GWs by this topography-jet mechanism. Conference Object Greenland Forschungszentrum Jülich: JuSER (Juelich Shared Electronic Resources) |
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Open Polar |
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Forschungszentrum Jülich: JuSER (Juelich Shared Electronic Resources) |
op_collection_id |
ftfzjuelichnvdb |
language |
English |
description |
In order to improve global atmospheric modelling, the trend is towards including source-specific gravity waves (GWs) in general circulation models. In a case study, we search for the source of a GW observed over Greenland on 10 March 2016 using the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) onboard the German research aircraft HALO. GLORIA is a remote sensing instrument where the measured infrared radiances are converted into a 3D temperature field through tomography. We observe a GW packet between 10 and 13km that covers ∼1/3 of the Greenland mainland. GLORIA observations indicate a horizontal (vertical) wavelength of 330km (2km) and a temperature amplitude of 4.5K. Slanted phase fronts indicate intrinsic propagation against the jet but the GW packet propagates (ground-based) with the wind. To find the GW source, 3D GLORIA observations, GROGRAT raytracer, ERA5 data, and an ECMWF numerical experiment are used. The numerical experiment with a smoothed topography indicates virtually no GWs suggesting that the GW field in the full model is caused by the orography. However, these are not mountain waves. A favourable area for spontaneous GW emission is identified within the jet exit region by the cross-stream ageostrophic wind speed, which indicates when the flow is not in geostrophic balance. Backtracing experiments (using GROGRAT) trace into the jet and imbalance regions. The difference between the full and the smooth-topography experiment is the change in wind components by the compression of air above Greenland. These accelerations and decelerations in the jet cause the jet to become out of geostrophic balance, which excites GWs by spontaneous adjustment. We present, to the best of our knowledge, the first observational evidence of GWs by this topography-jet mechanism. |
format |
Conference Object |
author |
Geldenhuys, Markus Preusse, Peter Krisch, Isabell Zuelicke, Christoph Ungermann, Jörn Ern, Manfred Friedl-Vallon, Felix Riese, Martin |
spellingShingle |
Geldenhuys, Markus Preusse, Peter Krisch, Isabell Zuelicke, Christoph Ungermann, Jörn Ern, Manfred Friedl-Vallon, Felix Riese, Martin A new mechanism for spontaneous imbalance exciting large-area gravity waves |
author_facet |
Geldenhuys, Markus Preusse, Peter Krisch, Isabell Zuelicke, Christoph Ungermann, Jörn Ern, Manfred Friedl-Vallon, Felix Riese, Martin |
author_sort |
Geldenhuys, Markus |
title |
A new mechanism for spontaneous imbalance exciting large-area gravity waves |
title_short |
A new mechanism for spontaneous imbalance exciting large-area gravity waves |
title_full |
A new mechanism for spontaneous imbalance exciting large-area gravity waves |
title_fullStr |
A new mechanism for spontaneous imbalance exciting large-area gravity waves |
title_full_unstemmed |
A new mechanism for spontaneous imbalance exciting large-area gravity waves |
title_sort |
new mechanism for spontaneous imbalance exciting large-area gravity waves |
publishDate |
2021 |
url |
https://juser.fz-juelich.de/record/892383 https://juser.fz-juelich.de/search?p=id:%22FZJ-2021-02044%22 |
op_coverage |
DE |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
doi:10.5194/egusphere-egu21-5591 European Geoscience Union 2021, EGU21, Online, Online, 2021-04-19 - 2021-04-30 |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/egusphere-egu21-5591 https://juser.fz-juelich.de/record/892383 https://juser.fz-juelich.de/search?p=id:%22FZJ-2021-02044%22 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.5194/egusphere-egu21-5591 |
_version_ |
1810446770237341696 |