Proper orthogonal decomposition of ice velocity identifies drivers of flow variability at Sermeq Kujalleq (Jakobshavn Isbræ)

The increasing volume and spatio-temporal resolution of satellite-derived ice velocity data have created new exploratory opportunities for the quantitative analysis of glacier dynamics. One potential technique, proper orthogonal decomposition (POD), also known as empirical orthogonal functions, has...

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Published in:The Cryosphere
Main Authors: D. W. Ashmore, D. W. F. Mair, J. E. Higham, S. Brough, J. M. Lea, I. J. Nias
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2022
Subjects:
Online Access:https://doi.org/10.5194/tc-16-219-2022
https://doaj.org/article/e86012e134bc440f9ae0bdd90f0c235e
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spelling ftdoajarticles:oai:doaj.org/article:e86012e134bc440f9ae0bdd90f0c235e 2023-05-15T16:21:26+02:00 Proper orthogonal decomposition of ice velocity identifies drivers of flow variability at Sermeq Kujalleq (Jakobshavn Isbræ) D. W. Ashmore D. W. F. Mair J. E. Higham S. Brough J. M. Lea I. J. Nias 2022-01-01T00:00:00Z https://doi.org/10.5194/tc-16-219-2022 https://doaj.org/article/e86012e134bc440f9ae0bdd90f0c235e EN eng Copernicus Publications https://tc.copernicus.org/articles/16/219/2022/tc-16-219-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-219-2022 1994-0416 1994-0424 https://doaj.org/article/e86012e134bc440f9ae0bdd90f0c235e The Cryosphere, Vol 16, Pp 219-236 (2022) Environmental sciences GE1-350 Geology QE1-996.5 article 2022 ftdoajarticles https://doi.org/10.5194/tc-16-219-2022 2022-12-30T20:15:49Z The increasing volume and spatio-temporal resolution of satellite-derived ice velocity data have created new exploratory opportunities for the quantitative analysis of glacier dynamics. One potential technique, proper orthogonal decomposition (POD), also known as empirical orthogonal functions, has proven to be a powerful and flexible technique for revealing coherent structures in a wide variety of environmental flows. In this study we investigate the applicability of POD to an openly available TanDEM-X/TerraSAR-X-derived ice velocity dataset from Sermeq Kujalleq (Jakobshavn Isbræ), Greenland. We find three dominant modes with annual periodicity that we argue are explained by glaciological processes. The primary dominant mode is interpreted as relating to the stress reconfiguration at the glacier terminus, known to be an important control on the glacier's dynamics. The second and third largest modes together relate to the development of the spatially heterogenous glacier hydrological system and are primarily driven by the pressurisation and efficiency of the subglacial hydrological system. During the melt season, variations in the velocity shown in these two subsidiary modes are explained by the drainage of nearby supraglacial melt ponds, as identified with a Google Earth Engine Moderate Resolution Imaging Spectroradiometer (MODIS) dynamic thresholding technique. By isolating statistical structures within velocity datasets and through their comparison to glaciological theory and complementary datasets, POD indicates which glaciological processes are responsible for the changing bulk velocity signal, as observed from space. With the proliferation of optical- and radar-derived velocity products (e.g. MEaSUREs, ESA CCI, PROMICE), we suggest POD, and potentially other modal decomposition techniques, will become increasingly useful in future studies of ice dynamics. Article in Journal/Newspaper glacier Greenland Jakobshavn Jakobshavn isbræ Kujalleq Sermeq Kujalleq The Cryosphere Directory of Open Access Journals: DOAJ Articles Greenland Jakobshavn Isbræ ENVELOPE(-49.917,-49.917,69.167,69.167) Kujalleq ENVELOPE(-46.037,-46.037,60.719,60.719) The Cryosphere 16 1 219 236
institution Open Polar
collection Directory of Open Access Journals: DOAJ Articles
op_collection_id ftdoajarticles
language English
topic Environmental sciences
GE1-350
Geology
QE1-996.5
spellingShingle Environmental sciences
GE1-350
Geology
QE1-996.5
D. W. Ashmore
D. W. F. Mair
J. E. Higham
S. Brough
J. M. Lea
I. J. Nias
Proper orthogonal decomposition of ice velocity identifies drivers of flow variability at Sermeq Kujalleq (Jakobshavn Isbræ)
topic_facet Environmental sciences
GE1-350
Geology
QE1-996.5
description The increasing volume and spatio-temporal resolution of satellite-derived ice velocity data have created new exploratory opportunities for the quantitative analysis of glacier dynamics. One potential technique, proper orthogonal decomposition (POD), also known as empirical orthogonal functions, has proven to be a powerful and flexible technique for revealing coherent structures in a wide variety of environmental flows. In this study we investigate the applicability of POD to an openly available TanDEM-X/TerraSAR-X-derived ice velocity dataset from Sermeq Kujalleq (Jakobshavn Isbræ), Greenland. We find three dominant modes with annual periodicity that we argue are explained by glaciological processes. The primary dominant mode is interpreted as relating to the stress reconfiguration at the glacier terminus, known to be an important control on the glacier's dynamics. The second and third largest modes together relate to the development of the spatially heterogenous glacier hydrological system and are primarily driven by the pressurisation and efficiency of the subglacial hydrological system. During the melt season, variations in the velocity shown in these two subsidiary modes are explained by the drainage of nearby supraglacial melt ponds, as identified with a Google Earth Engine Moderate Resolution Imaging Spectroradiometer (MODIS) dynamic thresholding technique. By isolating statistical structures within velocity datasets and through their comparison to glaciological theory and complementary datasets, POD indicates which glaciological processes are responsible for the changing bulk velocity signal, as observed from space. With the proliferation of optical- and radar-derived velocity products (e.g. MEaSUREs, ESA CCI, PROMICE), we suggest POD, and potentially other modal decomposition techniques, will become increasingly useful in future studies of ice dynamics.
format Article in Journal/Newspaper
author D. W. Ashmore
D. W. F. Mair
J. E. Higham
S. Brough
J. M. Lea
I. J. Nias
author_facet D. W. Ashmore
D. W. F. Mair
J. E. Higham
S. Brough
J. M. Lea
I. J. Nias
author_sort D. W. Ashmore
title Proper orthogonal decomposition of ice velocity identifies drivers of flow variability at Sermeq Kujalleq (Jakobshavn Isbræ)
title_short Proper orthogonal decomposition of ice velocity identifies drivers of flow variability at Sermeq Kujalleq (Jakobshavn Isbræ)
title_full Proper orthogonal decomposition of ice velocity identifies drivers of flow variability at Sermeq Kujalleq (Jakobshavn Isbræ)
title_fullStr Proper orthogonal decomposition of ice velocity identifies drivers of flow variability at Sermeq Kujalleq (Jakobshavn Isbræ)
title_full_unstemmed Proper orthogonal decomposition of ice velocity identifies drivers of flow variability at Sermeq Kujalleq (Jakobshavn Isbræ)
title_sort proper orthogonal decomposition of ice velocity identifies drivers of flow variability at sermeq kujalleq (jakobshavn isbræ)
publisher Copernicus Publications
publishDate 2022
url https://doi.org/10.5194/tc-16-219-2022
https://doaj.org/article/e86012e134bc440f9ae0bdd90f0c235e
long_lat ENVELOPE(-49.917,-49.917,69.167,69.167)
ENVELOPE(-46.037,-46.037,60.719,60.719)
geographic Greenland
Jakobshavn Isbræ
Kujalleq
geographic_facet Greenland
Jakobshavn Isbræ
Kujalleq
genre glacier
Greenland
Jakobshavn
Jakobshavn isbræ
Kujalleq
Sermeq Kujalleq
The Cryosphere
genre_facet glacier
Greenland
Jakobshavn
Jakobshavn isbræ
Kujalleq
Sermeq Kujalleq
The Cryosphere
op_source The Cryosphere, Vol 16, Pp 219-236 (2022)
op_relation https://tc.copernicus.org/articles/16/219/2022/tc-16-219-2022.pdf
https://doaj.org/toc/1994-0416
https://doaj.org/toc/1994-0424
doi:10.5194/tc-16-219-2022
1994-0416
1994-0424
https://doaj.org/article/e86012e134bc440f9ae0bdd90f0c235e
op_doi https://doi.org/10.5194/tc-16-219-2022
container_title The Cryosphere
container_volume 16
container_issue 1
container_start_page 219
op_container_end_page 236
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