Decadal geodetic variations in Ny-Alesund (Svalbard): role of past and present ice-mass changes
The geodetic rates for the gravity variation and vertical uplift in polar regions subject to past and present-day ice-mass changes (PDIMCs) provide important insight into the rheological structure of the Earth. We provide an update of the rates observed at Ny-lesund, Svalbard. To do so, we extract a...
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Language: | English |
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Blackwell Publishing Ltd
2014
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Online Access: | https://doi.org/10.1093/gji/ggu134 http://ecite.utas.edu.au/92730 |
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ftunivtasecite:oai:ecite.utas.edu.au:92730 2023-05-15T18:29:38+02:00 Decadal geodetic variations in Ny-Alesund (Svalbard): role of past and present ice-mass changes Memin, A Spada, G Boy, J-P Rogister, Y Hinderer, J 2014 application/pdf https://doi.org/10.1093/gji/ggu134 http://ecite.utas.edu.au/92730 en eng Blackwell Publishing Ltd http://ecite.utas.edu.au/92730/1/285-297 Memin.pdf http://dx.doi.org/10.1093/gji/ggu134 Memin, A and Spada, G and Boy, J-P and Rogister, Y and Hinderer, J, Decadal geodetic variations in Ny-Alesund (Svalbard): role of past and present ice-mass changes, Geophysical Journal International, 198, (1) pp. 285-297. ISSN 0956-540X (2014) [Refereed Article] http://ecite.utas.edu.au/92730 Engineering Geomatic Engineering Geodesy Refereed Article PeerReviewed 2014 ftunivtasecite https://doi.org/10.1093/gji/ggu134 2019-12-13T21:55:39Z The geodetic rates for the gravity variation and vertical uplift in polar regions subject to past and present-day ice-mass changes (PDIMCs) provide important insight into the rheological structure of the Earth. We provide an update of the rates observed at Ny-lesund, Svalbard. To do so, we extract and remove the significant seasonal content from the observations. The rate of gravity variations, derived from absolute and relative gravity measurements, is −1.39 0.11 μGal yr −1 . The rate of vertical displacements is estimated using GPS and tide gauge measurements. We obtain 7.94 0.21 and 8.29 1.60 mm yr −1 , respectively. We compare the extracted signal with that predicted by GLDAS/Noah and ERA-interim hydrology models. We find that the seasonal gravity variations are well-represented by local hydrology changes contained in the ERA-interim model. The phase of seasonal vertical displacements are due to non-local continental hydrology and non-tidal ocean loading. However, a large part of the amplitude of the seasonal vertical displacements remains unexplained. The geodetic rates are used to investigate the asthenosphere viscosity and lithosphere/asthenosphere thicknesses. We first correct the updated geodetic rates for those induced by PDIMCs in Svalbard, using published results, and the sea level change due to the melting of the major ice reservoirs. We show that the latter are at the level of the geodetic rate uncertainties and are responsible for rates of gravity variations and vertical displacements of −0.29 0.03 μGal yr −1 and 1.11 0.10 mm yr −1 , respectively. To account for the late Pleistocene deglaciation, we use the global ice evolution model ICE-3G. The Little Ice Age (LIA) deglaciation in Svalbard is modelled using a disc load model with a simple linear temporal evolution. The geodetic rates at Ny-lesund induced by the past deglaciations depend on the viscosity structure of the Earth. We find that viscous relaxation time due to the LIA deglaciation in Svalbard is more than 60 times shorter than that due to the Pleistocene deglaciation. We also find that the response to past and PDIMCs of an Earth model with asthenosphere viscosities ranging between 1.0 and 5.5 10 18 Pa s and lithosphere (resp. asthenosphere) thicknesses ranging between 50 and 100 km (resp. 120 and 170 km) can explain the rates derived from geodetic observations. Article in Journal/Newspaper Svalbard eCite UTAS (University of Tasmania) Lesund ENVELOPE(8.470,8.470,63.331,63.331) Svalbard Geophysical Journal International 198 1 285 297 |
institution |
Open Polar |
collection |
eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Engineering Geomatic Engineering Geodesy |
spellingShingle |
Engineering Geomatic Engineering Geodesy Memin, A Spada, G Boy, J-P Rogister, Y Hinderer, J Decadal geodetic variations in Ny-Alesund (Svalbard): role of past and present ice-mass changes |
topic_facet |
Engineering Geomatic Engineering Geodesy |
description |
The geodetic rates for the gravity variation and vertical uplift in polar regions subject to past and present-day ice-mass changes (PDIMCs) provide important insight into the rheological structure of the Earth. We provide an update of the rates observed at Ny-lesund, Svalbard. To do so, we extract and remove the significant seasonal content from the observations. The rate of gravity variations, derived from absolute and relative gravity measurements, is −1.39 0.11 μGal yr −1 . The rate of vertical displacements is estimated using GPS and tide gauge measurements. We obtain 7.94 0.21 and 8.29 1.60 mm yr −1 , respectively. We compare the extracted signal with that predicted by GLDAS/Noah and ERA-interim hydrology models. We find that the seasonal gravity variations are well-represented by local hydrology changes contained in the ERA-interim model. The phase of seasonal vertical displacements are due to non-local continental hydrology and non-tidal ocean loading. However, a large part of the amplitude of the seasonal vertical displacements remains unexplained. The geodetic rates are used to investigate the asthenosphere viscosity and lithosphere/asthenosphere thicknesses. We first correct the updated geodetic rates for those induced by PDIMCs in Svalbard, using published results, and the sea level change due to the melting of the major ice reservoirs. We show that the latter are at the level of the geodetic rate uncertainties and are responsible for rates of gravity variations and vertical displacements of −0.29 0.03 μGal yr −1 and 1.11 0.10 mm yr −1 , respectively. To account for the late Pleistocene deglaciation, we use the global ice evolution model ICE-3G. The Little Ice Age (LIA) deglaciation in Svalbard is modelled using a disc load model with a simple linear temporal evolution. The geodetic rates at Ny-lesund induced by the past deglaciations depend on the viscosity structure of the Earth. We find that viscous relaxation time due to the LIA deglaciation in Svalbard is more than 60 times shorter than that due to the Pleistocene deglaciation. We also find that the response to past and PDIMCs of an Earth model with asthenosphere viscosities ranging between 1.0 and 5.5 10 18 Pa s and lithosphere (resp. asthenosphere) thicknesses ranging between 50 and 100 km (resp. 120 and 170 km) can explain the rates derived from geodetic observations. |
format |
Article in Journal/Newspaper |
author |
Memin, A Spada, G Boy, J-P Rogister, Y Hinderer, J |
author_facet |
Memin, A Spada, G Boy, J-P Rogister, Y Hinderer, J |
author_sort |
Memin, A |
title |
Decadal geodetic variations in Ny-Alesund (Svalbard): role of past and present ice-mass changes |
title_short |
Decadal geodetic variations in Ny-Alesund (Svalbard): role of past and present ice-mass changes |
title_full |
Decadal geodetic variations in Ny-Alesund (Svalbard): role of past and present ice-mass changes |
title_fullStr |
Decadal geodetic variations in Ny-Alesund (Svalbard): role of past and present ice-mass changes |
title_full_unstemmed |
Decadal geodetic variations in Ny-Alesund (Svalbard): role of past and present ice-mass changes |
title_sort |
decadal geodetic variations in ny-alesund (svalbard): role of past and present ice-mass changes |
publisher |
Blackwell Publishing Ltd |
publishDate |
2014 |
url |
https://doi.org/10.1093/gji/ggu134 http://ecite.utas.edu.au/92730 |
long_lat |
ENVELOPE(8.470,8.470,63.331,63.331) |
geographic |
Lesund Svalbard |
geographic_facet |
Lesund Svalbard |
genre |
Svalbard |
genre_facet |
Svalbard |
op_relation |
http://ecite.utas.edu.au/92730/1/285-297 Memin.pdf http://dx.doi.org/10.1093/gji/ggu134 Memin, A and Spada, G and Boy, J-P and Rogister, Y and Hinderer, J, Decadal geodetic variations in Ny-Alesund (Svalbard): role of past and present ice-mass changes, Geophysical Journal International, 198, (1) pp. 285-297. ISSN 0956-540X (2014) [Refereed Article] http://ecite.utas.edu.au/92730 |
op_doi |
https://doi.org/10.1093/gji/ggu134 |
container_title |
Geophysical Journal International |
container_volume |
198 |
container_issue |
1 |
container_start_page |
285 |
op_container_end_page |
297 |
_version_ |
1766212832856113152 |