Monitoring ice flow velocity of Petermann glacier combined with Sentinel-1 and −2 imagery
Synthetic Aperture Radar (SAR) images are commonly used to monitor glacier flow velocity at Greenland Ice Sheet (GrIS). However, offset-tracking with SAR imagery in summer usually show poor quality because the rapid ice surface freezing-melting cycles contaminating the surface backscattering charact...
Published in: | International Journal of Applied Earth Observation and Geoinformation |
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Online Access: | https://doi.org/10.1016/j.jag.2023.103374 https://doaj.org/article/f404353dddd24272a3270892346fe025 |
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ftdoajarticles:oai:doaj.org/article:f404353dddd24272a3270892346fe025 2023-06-18T03:40:43+02:00 Monitoring ice flow velocity of Petermann glacier combined with Sentinel-1 and −2 imagery Gang Li Yanting Mao Xiaoman Feng Zhuoqi Chen Zhibin Yang Xiao Cheng 2023-07-01T00:00:00Z https://doi.org/10.1016/j.jag.2023.103374 https://doaj.org/article/f404353dddd24272a3270892346fe025 EN eng Elsevier http://www.sciencedirect.com/science/article/pii/S156984322300198X https://doaj.org/toc/1569-8432 1569-8432 doi:10.1016/j.jag.2023.103374 https://doaj.org/article/f404353dddd24272a3270892346fe025 International Journal of Applied Earth Observations and Geoinformation, Vol 121, Iss , Pp 103374- (2023) Glacier velocity Sentinel-1 Sentinel-2 Greenland ice sheet Offset-tracking SBAS Physical geography GB3-5030 Environmental sciences GE1-350 article 2023 ftdoajarticles https://doi.org/10.1016/j.jag.2023.103374 2023-06-04T00:33:11Z Synthetic Aperture Radar (SAR) images are commonly used to monitor glacier flow velocity at Greenland Ice Sheet (GrIS). However, offset-tracking with SAR imagery in summer usually show poor quality because the rapid ice surface freezing-melting cycles contaminating the surface backscattering characteristic, while optical images are less sensitive to this phenomenon. In this study, we combine Sentinel-1 and -2 images to create the glacier velocity time series for the Petermann glacier, located in the northern GrIS. Firstly, the offset-tracking technique is employed to acquire the initial deformation fields with SAR and optical sensors separately, each SAR and/or optical acquisition is tracked with its closest next three acquisitions. Next, after removing the bad matchings, the least squares method based on connected components is employed to calculate the time series of glacier velocity for Sentinel-1 and −2, separately. Finally, these two kinds of derived time series are integrated with a weighted least squares method, where weights are evaluated according to the estimated RMSEs in the last step. Error propagation analysis suggests RMSEs of the single pair of Sentinel-1 and −2 images offset-tracking are ∼ 0.22 m and ∼ 2.5 m for Petermann glaciers. Standard deviation of the difference between Sentinel-1 and Sentinel-2 measured velocity are ∼ 0.25 m/day. Compared with 6-day velocity fields product, NSIDC (National Snow and Ice Data Center) −0766, which is only derived with Sentinel-1observations, our results show good agreement and less defects in summer. The differences are ∼ 0.20 m/day in non-melting seasons and ∼ 0.34 m/day in summer. Longitudinal velocity differences growing in 2019 and 2020 at ∼ 20 Km up to the terminus are consistency with the crevasse expansion, indicating another calving event is approaching. This research finds that the fusion of Sentinel-1 and −2 offset-tracking results improves the completeness of the ice movement time series for polar glaciers. Article in Journal/Newspaper glacier Greenland Ice Sheet National Snow and Ice Data Center Petermann glacier Directory of Open Access Journals: DOAJ Articles Greenland International Journal of Applied Earth Observation and Geoinformation 121 103374 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Glacier velocity Sentinel-1 Sentinel-2 Greenland ice sheet Offset-tracking SBAS Physical geography GB3-5030 Environmental sciences GE1-350 |
spellingShingle |
Glacier velocity Sentinel-1 Sentinel-2 Greenland ice sheet Offset-tracking SBAS Physical geography GB3-5030 Environmental sciences GE1-350 Gang Li Yanting Mao Xiaoman Feng Zhuoqi Chen Zhibin Yang Xiao Cheng Monitoring ice flow velocity of Petermann glacier combined with Sentinel-1 and −2 imagery |
topic_facet |
Glacier velocity Sentinel-1 Sentinel-2 Greenland ice sheet Offset-tracking SBAS Physical geography GB3-5030 Environmental sciences GE1-350 |
description |
Synthetic Aperture Radar (SAR) images are commonly used to monitor glacier flow velocity at Greenland Ice Sheet (GrIS). However, offset-tracking with SAR imagery in summer usually show poor quality because the rapid ice surface freezing-melting cycles contaminating the surface backscattering characteristic, while optical images are less sensitive to this phenomenon. In this study, we combine Sentinel-1 and -2 images to create the glacier velocity time series for the Petermann glacier, located in the northern GrIS. Firstly, the offset-tracking technique is employed to acquire the initial deformation fields with SAR and optical sensors separately, each SAR and/or optical acquisition is tracked with its closest next three acquisitions. Next, after removing the bad matchings, the least squares method based on connected components is employed to calculate the time series of glacier velocity for Sentinel-1 and −2, separately. Finally, these two kinds of derived time series are integrated with a weighted least squares method, where weights are evaluated according to the estimated RMSEs in the last step. Error propagation analysis suggests RMSEs of the single pair of Sentinel-1 and −2 images offset-tracking are ∼ 0.22 m and ∼ 2.5 m for Petermann glaciers. Standard deviation of the difference between Sentinel-1 and Sentinel-2 measured velocity are ∼ 0.25 m/day. Compared with 6-day velocity fields product, NSIDC (National Snow and Ice Data Center) −0766, which is only derived with Sentinel-1observations, our results show good agreement and less defects in summer. The differences are ∼ 0.20 m/day in non-melting seasons and ∼ 0.34 m/day in summer. Longitudinal velocity differences growing in 2019 and 2020 at ∼ 20 Km up to the terminus are consistency with the crevasse expansion, indicating another calving event is approaching. This research finds that the fusion of Sentinel-1 and −2 offset-tracking results improves the completeness of the ice movement time series for polar glaciers. |
format |
Article in Journal/Newspaper |
author |
Gang Li Yanting Mao Xiaoman Feng Zhuoqi Chen Zhibin Yang Xiao Cheng |
author_facet |
Gang Li Yanting Mao Xiaoman Feng Zhuoqi Chen Zhibin Yang Xiao Cheng |
author_sort |
Gang Li |
title |
Monitoring ice flow velocity of Petermann glacier combined with Sentinel-1 and −2 imagery |
title_short |
Monitoring ice flow velocity of Petermann glacier combined with Sentinel-1 and −2 imagery |
title_full |
Monitoring ice flow velocity of Petermann glacier combined with Sentinel-1 and −2 imagery |
title_fullStr |
Monitoring ice flow velocity of Petermann glacier combined with Sentinel-1 and −2 imagery |
title_full_unstemmed |
Monitoring ice flow velocity of Petermann glacier combined with Sentinel-1 and −2 imagery |
title_sort |
monitoring ice flow velocity of petermann glacier combined with sentinel-1 and −2 imagery |
publisher |
Elsevier |
publishDate |
2023 |
url |
https://doi.org/10.1016/j.jag.2023.103374 https://doaj.org/article/f404353dddd24272a3270892346fe025 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
glacier Greenland Ice Sheet National Snow and Ice Data Center Petermann glacier |
genre_facet |
glacier Greenland Ice Sheet National Snow and Ice Data Center Petermann glacier |
op_source |
International Journal of Applied Earth Observations and Geoinformation, Vol 121, Iss , Pp 103374- (2023) |
op_relation |
http://www.sciencedirect.com/science/article/pii/S156984322300198X https://doaj.org/toc/1569-8432 1569-8432 doi:10.1016/j.jag.2023.103374 https://doaj.org/article/f404353dddd24272a3270892346fe025 |
op_doi |
https://doi.org/10.1016/j.jag.2023.103374 |
container_title |
International Journal of Applied Earth Observation and Geoinformation |
container_volume |
121 |
container_start_page |
103374 |
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1769005961694937088 |