Seasonal Variations in Drag Coefficient over a Sastrugi-Covered Snowfield in Coastal East Antarctica
International audience The surface of windy Antarctic snowfields is subject to drifting snow, which leads to the formation of sastrugi. In turn, sastrugi contribute to the drag exerted by the snow surface on the atmosphere and hence influence drifting snow. Although the surface drag over rough sastr...
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ftunigrenoble:oai:HAL:hal-01985034v1 2023-05-15T13:04:23+02:00 Seasonal Variations in Drag Coefficient over a Sastrugi-Covered Snowfield in Coastal East Antarctica Amory, Charles Gallée, Hubert Naaim-Bouvet, Florence Favier, Vincent Vignon, Etienne Picard, Ghislain Trouvilliez, Alexandre Piard, Luc Genthon, Christophe Bellot, Hervé Institut des Géosciences de l’Environnement (IGE) Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ) University of Lieges Erosion torrentielle neige et avalanches (UR ETGR (ETNA)) Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA) Glaciers et ressources en eau d'altitude - Indicateurs climatiques et environnementaux (GREATICE) 2017-07 https://hal.archives-ouvertes.fr/hal-01985034 en eng HAL CCSD Springer Verlag hal-01985034 https://hal.archives-ouvertes.fr/hal-01985034 ISSN: 0006-8314 EISSN: 1573-1472 Boundary-Layer Meteorology https://hal.archives-ouvertes.fr/hal-01985034 Boundary-Layer Meteorology, Springer Verlag, 2017, 164 (1), pp.107-133 Snow surface roughness Sastrugi Drifting snow Antarctica Drag coefficient [SDU]Sciences of the Universe [physics] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDE]Environmental Sciences info:eu-repo/semantics/article Journal articles 2017 ftunigrenoble 2021-05-11T22:40:34Z International audience The surface of windy Antarctic snowfields is subject to drifting snow, which leads to the formation of sastrugi. In turn, sastrugi contribute to the drag exerted by the snow surface on the atmosphere and hence influence drifting snow. Although the surface drag over rough sastrugi fields has been estimated for individual locations in Antarctica, its variation over time and with respect to drifting snow has received little attention. Using year-round data from a meteorological mast, seasonal variations in the neutral drag coefficient at a height of 10 m (CDN10) in coastal Adelie Land are presented and discussed in light of the formation and behaviour of sastrugi based on observed aeolian erosion patterns. The measurements revealed high CDN10 values (≥ 2 × 10−3) and limited drifting snow (35% of the time) in summer (December–February) versus lower CDN10 values (≈ 1.5 × 10−3) associated with more frequent drifting snow (70% of the time) in winter (March–November). Without the seasonal distinction, there was no clear dependence of CDN10 on friction velocity or wind direction, but observations revealed a general increase in CDN10 with rising air temperature. The main hypothesis defended here is that higher temperatures increase snow cohesion and the development of sastrugi just after snow deposition while inhibiting the sastrugi streamlining process by raising the erosion threshold. This increases the contribution of the sastrugi form drag to the total surface drag in summer when winds are lighter and more variable. The analysis also showed that, in the absence of erosion, single snowfall events can reduce CDN10 to 1×10−3 due to the burying of pre-existing microrelief under newly deposited snow. The results suggest that polar atmospheric models should account for spatial and temporal variations in snow surface roughness through a dynamic representation of the sastrugi form drag. Article in Journal/Newspaper Adelie Land Antarc* Antarctic Antarctica East Antarctica Université Grenoble Alpes: HAL Antarctic East Antarctica Sastrugi ENVELOPE(163.683,163.683,-74.617,-74.617) |
institution |
Open Polar |
collection |
Université Grenoble Alpes: HAL |
op_collection_id |
ftunigrenoble |
language |
English |
topic |
Snow surface roughness Sastrugi Drifting snow Antarctica Drag coefficient [SDU]Sciences of the Universe [physics] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDE]Environmental Sciences |
spellingShingle |
Snow surface roughness Sastrugi Drifting snow Antarctica Drag coefficient [SDU]Sciences of the Universe [physics] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDE]Environmental Sciences Amory, Charles Gallée, Hubert Naaim-Bouvet, Florence Favier, Vincent Vignon, Etienne Picard, Ghislain Trouvilliez, Alexandre Piard, Luc Genthon, Christophe Bellot, Hervé Seasonal Variations in Drag Coefficient over a Sastrugi-Covered Snowfield in Coastal East Antarctica |
topic_facet |
Snow surface roughness Sastrugi Drifting snow Antarctica Drag coefficient [SDU]Sciences of the Universe [physics] [SDU.OCEAN]Sciences of the Universe [physics]/Ocean Atmosphere [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment [SDE]Environmental Sciences |
description |
International audience The surface of windy Antarctic snowfields is subject to drifting snow, which leads to the formation of sastrugi. In turn, sastrugi contribute to the drag exerted by the snow surface on the atmosphere and hence influence drifting snow. Although the surface drag over rough sastrugi fields has been estimated for individual locations in Antarctica, its variation over time and with respect to drifting snow has received little attention. Using year-round data from a meteorological mast, seasonal variations in the neutral drag coefficient at a height of 10 m (CDN10) in coastal Adelie Land are presented and discussed in light of the formation and behaviour of sastrugi based on observed aeolian erosion patterns. The measurements revealed high CDN10 values (≥ 2 × 10−3) and limited drifting snow (35% of the time) in summer (December–February) versus lower CDN10 values (≈ 1.5 × 10−3) associated with more frequent drifting snow (70% of the time) in winter (March–November). Without the seasonal distinction, there was no clear dependence of CDN10 on friction velocity or wind direction, but observations revealed a general increase in CDN10 with rising air temperature. The main hypothesis defended here is that higher temperatures increase snow cohesion and the development of sastrugi just after snow deposition while inhibiting the sastrugi streamlining process by raising the erosion threshold. This increases the contribution of the sastrugi form drag to the total surface drag in summer when winds are lighter and more variable. The analysis also showed that, in the absence of erosion, single snowfall events can reduce CDN10 to 1×10−3 due to the burying of pre-existing microrelief under newly deposited snow. The results suggest that polar atmospheric models should account for spatial and temporal variations in snow surface roughness through a dynamic representation of the sastrugi form drag. |
author2 |
Institut des Géosciences de l’Environnement (IGE) Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ) University of Lieges Erosion torrentielle neige et avalanches (UR ETGR (ETNA)) Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA) Glaciers et ressources en eau d'altitude - Indicateurs climatiques et environnementaux (GREATICE) |
format |
Article in Journal/Newspaper |
author |
Amory, Charles Gallée, Hubert Naaim-Bouvet, Florence Favier, Vincent Vignon, Etienne Picard, Ghislain Trouvilliez, Alexandre Piard, Luc Genthon, Christophe Bellot, Hervé |
author_facet |
Amory, Charles Gallée, Hubert Naaim-Bouvet, Florence Favier, Vincent Vignon, Etienne Picard, Ghislain Trouvilliez, Alexandre Piard, Luc Genthon, Christophe Bellot, Hervé |
author_sort |
Amory, Charles |
title |
Seasonal Variations in Drag Coefficient over a Sastrugi-Covered Snowfield in Coastal East Antarctica |
title_short |
Seasonal Variations in Drag Coefficient over a Sastrugi-Covered Snowfield in Coastal East Antarctica |
title_full |
Seasonal Variations in Drag Coefficient over a Sastrugi-Covered Snowfield in Coastal East Antarctica |
title_fullStr |
Seasonal Variations in Drag Coefficient over a Sastrugi-Covered Snowfield in Coastal East Antarctica |
title_full_unstemmed |
Seasonal Variations in Drag Coefficient over a Sastrugi-Covered Snowfield in Coastal East Antarctica |
title_sort |
seasonal variations in drag coefficient over a sastrugi-covered snowfield in coastal east antarctica |
publisher |
HAL CCSD |
publishDate |
2017 |
url |
https://hal.archives-ouvertes.fr/hal-01985034 |
long_lat |
ENVELOPE(163.683,163.683,-74.617,-74.617) |
geographic |
Antarctic East Antarctica Sastrugi |
geographic_facet |
Antarctic East Antarctica Sastrugi |
genre |
Adelie Land Antarc* Antarctic Antarctica East Antarctica |
genre_facet |
Adelie Land Antarc* Antarctic Antarctica East Antarctica |
op_source |
ISSN: 0006-8314 EISSN: 1573-1472 Boundary-Layer Meteorology https://hal.archives-ouvertes.fr/hal-01985034 Boundary-Layer Meteorology, Springer Verlag, 2017, 164 (1), pp.107-133 |
op_relation |
hal-01985034 https://hal.archives-ouvertes.fr/hal-01985034 |
_version_ |
1766358452565704704 |