Gravity Wave Excitation during the Coastal Transition of an Extreme Katabatic Flow in Antarctica
The offshore extent of Antarctic katabatic winds exerts a strong control on the production of sea ice and the formation of polynyas. In this study, we make use of a combination of ground-based remotely sensed and meteorological measurements at Dumont d'Urville (DDU) station, satellite images, a...
Published in: | Journal of the Atmospheric Sciences |
---|---|
Main Authors: | , , , , , |
Format: | Text |
Language: | unknown |
Published: |
2020
|
Subjects: | |
Online Access: | https://doi.org/10.1175/JAS-D-19-0264.1 https://infoscience.epfl.ch/record/277494/files/Pdf.pdf http://infoscience.epfl.ch/record/277494 |
id |
ftinfoscience:oai:infoscience.epfl.ch:277494 |
---|---|
record_format |
openpolar |
spelling |
ftinfoscience:oai:infoscience.epfl.ch:277494 2023-05-15T13:04:13+02:00 Gravity Wave Excitation during the Coastal Transition of an Extreme Katabatic Flow in Antarctica Vignon, Etienne Picard, Ghislain Duran-Alarcon, Claudio Alexander, Simon P. Gallee, Hubert Berne, Alexis 2020-05-13T00:20:37Z https://doi.org/10.1175/JAS-D-19-0264.1 https://infoscience.epfl.ch/record/277494/files/Pdf.pdf http://infoscience.epfl.ch/record/277494 unknown doi:10.1175/JAS-D-19-0264.1 isi:000528754800004 https://infoscience.epfl.ch/record/277494/files/Pdf.pdf http://infoscience.epfl.ch/record/277494 http://infoscience.epfl.ch/record/277494 Text 2020 ftinfoscience https://doi.org/10.1175/JAS-D-19-0264.1 2023-02-13T23:00:02Z The offshore extent of Antarctic katabatic winds exerts a strong control on the production of sea ice and the formation of polynyas. In this study, we make use of a combination of ground-based remotely sensed and meteorological measurements at Dumont d'Urville (DDU) station, satellite images, and simulations with the Weather Research and Forecasting Model to analyze a major katabatic wind event in Adelie Land. Once well developed over the slope of the ice sheet, the katabatic flow experiences an abrupt transition near the coastal edge consisting of a sharp increase in the boundary layer depth, a sudden decrease in wind speed, and a decrease in Froude number from 3.5 to 0.3. This so-called katabatic jump manifests as a turbulent "wall" of blowing snow in which updrafts exceed 5 m s(-1). The wall reaches heights of 1000 m and its horizontal extent along the coast is more than 400 km. By destabilizing the boundary layer downstream, the jump favors the trapping of a gravity wave train-with a horizontal wavelength of 10.5 km-that develops in a few hours. The trapped gravity waves exert a drag that considerably slows down the low-level outflow. Moreover, atmospheric rotors form below the first wave crests. The wind speed record measured at DDU in 2017 (58.5 m s(-1)) is due to the vertical advection of momentum by a rotor. A statistical analysis of observations at DDU reveals that katabatic jumps and low-level trapped gravity waves occur frequently over coastal Adelie Land. It emphasizes the important role of such phenomena in the coastal Antarctic dynamics. Text Adelie Land Antarc* Antarctic Antarctica Ice Sheet Sea ice EPFL Infoscience (Ecole Polytechnique Fédérale Lausanne) Antarctic Dumont d'Urville ENVELOPE(140.017,140.017,-66.667,-66.667) Dumont-d'Urville ENVELOPE(140.013,140.013,-66.667,-66.667) Journal of the Atmospheric Sciences 77 4 1295 1312 |
institution |
Open Polar |
collection |
EPFL Infoscience (Ecole Polytechnique Fédérale Lausanne) |
op_collection_id |
ftinfoscience |
language |
unknown |
description |
The offshore extent of Antarctic katabatic winds exerts a strong control on the production of sea ice and the formation of polynyas. In this study, we make use of a combination of ground-based remotely sensed and meteorological measurements at Dumont d'Urville (DDU) station, satellite images, and simulations with the Weather Research and Forecasting Model to analyze a major katabatic wind event in Adelie Land. Once well developed over the slope of the ice sheet, the katabatic flow experiences an abrupt transition near the coastal edge consisting of a sharp increase in the boundary layer depth, a sudden decrease in wind speed, and a decrease in Froude number from 3.5 to 0.3. This so-called katabatic jump manifests as a turbulent "wall" of blowing snow in which updrafts exceed 5 m s(-1). The wall reaches heights of 1000 m and its horizontal extent along the coast is more than 400 km. By destabilizing the boundary layer downstream, the jump favors the trapping of a gravity wave train-with a horizontal wavelength of 10.5 km-that develops in a few hours. The trapped gravity waves exert a drag that considerably slows down the low-level outflow. Moreover, atmospheric rotors form below the first wave crests. The wind speed record measured at DDU in 2017 (58.5 m s(-1)) is due to the vertical advection of momentum by a rotor. A statistical analysis of observations at DDU reveals that katabatic jumps and low-level trapped gravity waves occur frequently over coastal Adelie Land. It emphasizes the important role of such phenomena in the coastal Antarctic dynamics. |
format |
Text |
author |
Vignon, Etienne Picard, Ghislain Duran-Alarcon, Claudio Alexander, Simon P. Gallee, Hubert Berne, Alexis |
spellingShingle |
Vignon, Etienne Picard, Ghislain Duran-Alarcon, Claudio Alexander, Simon P. Gallee, Hubert Berne, Alexis Gravity Wave Excitation during the Coastal Transition of an Extreme Katabatic Flow in Antarctica |
author_facet |
Vignon, Etienne Picard, Ghislain Duran-Alarcon, Claudio Alexander, Simon P. Gallee, Hubert Berne, Alexis |
author_sort |
Vignon, Etienne |
title |
Gravity Wave Excitation during the Coastal Transition of an Extreme Katabatic Flow in Antarctica |
title_short |
Gravity Wave Excitation during the Coastal Transition of an Extreme Katabatic Flow in Antarctica |
title_full |
Gravity Wave Excitation during the Coastal Transition of an Extreme Katabatic Flow in Antarctica |
title_fullStr |
Gravity Wave Excitation during the Coastal Transition of an Extreme Katabatic Flow in Antarctica |
title_full_unstemmed |
Gravity Wave Excitation during the Coastal Transition of an Extreme Katabatic Flow in Antarctica |
title_sort |
gravity wave excitation during the coastal transition of an extreme katabatic flow in antarctica |
publishDate |
2020 |
url |
https://doi.org/10.1175/JAS-D-19-0264.1 https://infoscience.epfl.ch/record/277494/files/Pdf.pdf http://infoscience.epfl.ch/record/277494 |
long_lat |
ENVELOPE(140.017,140.017,-66.667,-66.667) ENVELOPE(140.013,140.013,-66.667,-66.667) |
geographic |
Antarctic Dumont d'Urville Dumont-d'Urville |
geographic_facet |
Antarctic Dumont d'Urville Dumont-d'Urville |
genre |
Adelie Land Antarc* Antarctic Antarctica Ice Sheet Sea ice |
genre_facet |
Adelie Land Antarc* Antarctic Antarctica Ice Sheet Sea ice |
op_source |
http://infoscience.epfl.ch/record/277494 |
op_relation |
doi:10.1175/JAS-D-19-0264.1 isi:000528754800004 https://infoscience.epfl.ch/record/277494/files/Pdf.pdf http://infoscience.epfl.ch/record/277494 |
op_doi |
https://doi.org/10.1175/JAS-D-19-0264.1 |
container_title |
Journal of the Atmospheric Sciences |
container_volume |
77 |
container_issue |
4 |
container_start_page |
1295 |
op_container_end_page |
1312 |
_version_ |
1766355165441425408 |