Identification and tracking of individual sea ice floes from ENVISAT wide swath SAR images: a case study from Fram Strait

AbstractThe results are presented of the first winter ice navigation demonstration, using synthetic aperture radar (SAR) images from the Canadian satellite RADARSAT, onboard the nuclear icebreaker Sovetskiy Soyuz in the Kara Sea region in April–May 1998. While ERS SAR data only could cover part of the sea ice in this large area, the demonstration showed that RADARSAT ScanSAR images with 100 m pixel size could be used to map all relevant ice areas with a few 500 × 500 km scenes. SAR images transferred onboard icebreakers in near real time offer an excellent possibility to select optimal sailing routes in difficult ice conditions such as those that were encountered by this expedition. SAR images were also used for planning of operations prior to the expedition. This study compares sub-satellite sea-ice observations with RADARSAT SAR as well as Okean side-looking radar (SLR) signatures of the major ice types and features found in the Kara Sea during winter. Wide-swath SAR images will become available from several new satellites in the near future, such as Envisat, scheduled in 2001, and RADARSAT-2, in 2002. Satellite SAR images will therefore play an increasingly important role in operational ice monitoring both in the Northern Sea Route and in other ice areas.

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Use of L- and C-Band SAR Satellites for Sea Ice and Iceberg Monitoring (LC-ICE)

10.5194/egusphere-egu21-3916 ◽

2021 ◽

Author(s):

Wolfgang Dierking ◽

Malcolm Davidson

Keyword(s):

Sea Ice ◽

Advisory Group ◽

Automated Classification ◽

Sar Images ◽

Mutual Cooperation ◽

Current State ◽

L Band ◽

Sar Imagery ◽

Using Data ◽

Wide Swath

<p>In support of ESA's&#160;Mission Advisory Group for ROSE-L (Radar Observing System for Europe at L-band), a project team consisting of members of operational ice services and&#160;the International Ice Charting Working Group,&#160; the International Ice Patrol, and&#160;groups from universities and research institutes is investigating the benefits of using data from&#160;L-band SAR&#160;in addition to C-band SAR imagery for separating different sea ice classes and detecting icebergs. The tasks are: (1)&#160;a critical assessment of the current state-of-the-art&#160;in sea ice monitoring and iceberg detection, (2)&#160;matching C- and L-band SAR images acquired with temporal&#160;gaps of several hours, (3)&#160;tests and assessments of the&#160;practical use of L-band images in the operational mapping services, and (4)&#160;comparison of classification accuracies that can be achieved at C-band, L-band, and a combination of both, based on the results&#160;of automated&#160;segmentation and classification algorithms. Based on the suggestions of operational ice centers, data have been collected since April 2019&#160;over&#160;six test sites&#160;for the Northern Hemisphere: Fram Strait,&#160;Belgica&#160;Bank, northern and southern parts of Greenland, Baffin Bay and&#160;Labrador Sea. The SAR images are acquired by Sentinel-1 at&#160;Extra Wide and Interferomeric Wide Swath modes, by RADARSAT-2 at ScanSAR mode,&#160;and by&#160;ALOS-2 PALSAR-2 at&#160;Wide Beam and Fine Beam modes. The PALSAR-2 data are provided through the 2019 to 2022 mutual cooperation project between ESA and JAXA on using SAR data in earth sciences and applications. The presentation - with contributions from project partners - will focus on the conclusions from the literature review, assessments&#160;of&#160;operational ice services regarding the gain they find in using L-band SAR images supplementary to routinely analyzed C-band imagery, and preliminary results of automated classification.&#160;</p>

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Validation of remote-sensing products of sea-ice motion: a case study in the western Arctic Ocean

Journal of Glaciology ◽

10.1017/jog.2020.49 ◽

2020 ◽

Vol 66 (259) ◽

pp. 807-821

Author(s):

Dawei Gui ◽

Ruibo Lei ◽

Xiaoping Pang ◽

Jennifer K. Hutchings ◽

Guangyu Zuo ◽

...

Keyword(s):

Remote Sensing ◽

Sea Ice ◽

Arctic Ocean ◽

Sea Ice Concentration ◽

Western Arctic Ocean ◽

Ice Concentration ◽

Western Arctic ◽

Ice Floes ◽

Relative Errors

AbstractThe accuracy of sea-ice motion products provided by the National Snow and Ice Data Center (NSIDC) and the Ocean and Sea Ice Satellite Application Facility (OSI-SAF) was validated with data collected by ice drifters that were deployed in the western Arctic Ocean in 2014 and 2016. Data from both NSIDC and OSI-SAF products exhibited statistically significant (p < 0.001) correlation with drifter data. The OSI-SAF product tended to overestimate ice speed, while underestimation was demonstrated for the NSIDC product, especially for the melt season and the marginal ice zone. Monthly Lagrangian trajectories of ice floes were reconstructed using the products. Larger spatial variability in the deviation between NSIDC and drifter trajectories was observed than that of OSI-SAF, and seasonal variability in the deviation for NSIDC was observed. Furthermore, trajectories reconstructed using the NSIDC product were sensitive to variations in sea-ice concentration. The feasibility of using remote-sensing products to characterize sea-ice deformation was assessed by evaluating the distance between two arbitrary positions as estimated by the products. Compared with the OSI-SAF product, relative errors are lower (<11.6%), and spatial-temporal resolutions are higher in the NSIDC product, which makes it more suitable for estimating sea-ice deformation.

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Sea ice drift and arch evolution in the Robeson Channel using the daily coverage of Sentinel-1 SAR data for the 2016–2017 freezing season

The Cryosphere ◽

10.5194/tc-14-3611-2020 ◽

2020 ◽

Vol 14 (11) ◽

pp. 3611-3627

Author(s):

Mohammed E. Shokr ◽

Zihan Wang ◽

Tingting Liu

Keyword(s):

Sea Ice ◽

Sea Water ◽

Linear Trend ◽

Ice Cover ◽

The Arctic ◽

Sar Images ◽

Ice Drift ◽

Sea Ice Drift ◽

Ice Floes

Abstract. The Robeson Channel is a narrow sea water passage between Greenland and Ellesmere Island in the Arctic. It is a pathway of sea ice from the central Arctic and out to Baffin Bay. In this study, we used a set of daily synthetic aperture radar (SAR) images from the Sentinel-1A/1B satellites, acquired between September 2016 and April 2017, to study the kinematics of individual ice floes as they approach and then drift through the Robeson Channel. The tracking of 39 selected ice floes was visually performed in the image sequence, and their speed was calculated and linked to the reanalysis 10 m wind from ERA5. The results show that the drift of ice floes is very slow in the compact ice regime upstream of the Robeson Channel, unless the ice floe is surrounded by water or thin ice. In this case, the wind has more influence on the drift. On the other hand, the ice floe drift is found to be about 4–5 times faster in the open-drift regime within the Robeson Channel and is clearly influenced by wind. A linear trend is found between the change in wind and the change in ice drift speed components, along the length of the channel. Case studies are presented to reveal the role of wind in ice floe drift. This paper also addresses the development of the ice arch at the entry of the Robeson Channel, which started development on 24 January and matured on 1 February 2017. Details of the development, obtained using the sequential SAR images, are presented. It is found that the arch's shape continued to adjust by rupturing ice pieces at the locations of cracks under the influence of the southward wind (and hence the contour kept displacing northward). The findings of this study highlight the advantage of using the high-resolution daily SAR coverage in monitoring aspects of sea ice cover in narrow water passages where the ice cover is highly dynamic. The information will be particularly interesting for the possible applications of SAR constellation systems.

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Influence of synoptic atmospheric conditions on movement of individual sea-ice floes in Fram Strait, late summer 2010

Annals of Glaciology ◽

10.3189/2015aog69a655 ◽

2015 ◽

Vol 56 (69) ◽

pp. 445-450

Author(s):

Jennifer A. King ◽

Grant R. Bigg ◽

Richard Hall

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Late Summer ◽

The Arctic ◽

Boreal Summer ◽

Fram Strait ◽

Atmospheric Conditions ◽

Ice Dynamics ◽

The Arctic Ocean ◽

Ice Floes

AbstractIn this paper we investigate the effect on sea-ice movement of changes in the synoptic atmospheric conditions in late boreal summer 2010. Our study area is the western Fram Strait, a crucial passage for the transport of ice out of the Arctic basin. Ice dynamics here affect the movement of ice in the East Greenland Current, the transpolar drift and ice extent in the Arctic Ocean. In contrast to other times of the year, when the Fram Strait wind field is characterized by strong, persistent northerlies, we show that the weaker, more variable winds typical during late summer for the Fram Strait can slow movement of ice floes out of the area, thus slowing the export of ice from the Arctic Ocean at the end of summer, a time crucial for ice export. The Arctic Ocean could lose even more of the ice that survives the summer if this was not the case. This would leave the Arctic Ocean in an even more vulnerable position with regard to the amount of multi-year ice remaining the following summer.

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Sea Ice Drift and Arch Formation in the Robeson Channel Using Daily Coverage of Sentinel-1 SAR Data During the 2016–2017 Freezing Season

10.5194/tc-2020-44 ◽

2020 ◽

Author(s):

Mohammed E. Shokr ◽

Zihan Wang ◽

Tingting Liu

Keyword(s):

Sea Ice ◽

Sea Water ◽

Linear Trend ◽

Ice Cover ◽

The Arctic ◽

Sar Images ◽

Northerly Wind ◽

Ice Drift ◽

Sea Ice Drift ◽

Ice Floes

Abstract. Robeson Channel (RC) is a narrow sea water passage between Greenland and Ellesmere Island in the Arctic. It is a pathway of sea ice from the central Arctic and out to the Baffin Bay. This paper uses a set of daily Synthetic Aperture Radar (SAR) images from Sentinel-1A/1B, acquired between September 2016 and April 2017, to study kinematics of individual ice floes as they approach then drift through the RC. Tracking of 39 selected floes was visually performed in the image sequence and their speed was calculated and linked to the reanalysis 10 m wind from ERA5. Results show that drift of ice floes is remarkably slow while in the compact ice regime upstream of the RC unless the floe is surrounded by water or thin ice. In this case the wind has more influence on the drift. On the other hand, ice floe drift is found to be about 4–5 times faster in the open drift regime within the RC and clearly influenced by wind. A linear trend is found between change in wind and change in ice drift speed components, both along the length of the channel. Case studies are presented to reveal the role of wind on ice floe drift in details. The study also addresses the development of the ice arch at the entry of the channel. It started development on 24 January and matured on 1 February 2017. Details of the formation process, using the sequential SAR images, are presented. The arch’s shape continued to adjust by rupturing ice pieces at locations of cracks under the influence of northerly wind (hence the contour keeps displacing northward). The study highlights the advantage of using the high-resolution daily SAR coverage in monitoring aspects of sea ice cover in narrow water passages where the ice cover is highly dynamic. The information will be particularly interesting for possible applications of SAR constellation systems.

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Eddies in the Marginal Ice Zone of Fram Strait and Svalbard from Spaceborne SAR Observations in Winter

Remote Sensing ◽

10.3390/rs14010134 ◽

2021 ◽

Vol 14 (1) ◽

pp. 134

Author(s):

Igor E. Kozlov ◽

Oksana A. Atadzhanova

Keyword(s):

Sea Ice ◽

Fram Strait ◽

Sar Images ◽

Mean Values ◽

Envisat Asar ◽

Ice Melt ◽

Ice Concentration ◽

Marginal Ice Zone ◽

Eddy Generation ◽

Ice Edge

Here we investigate the intensity of eddy generation and their properties in the marginal ice zone (MIZ) regions of Fram Strait and around Svalbard using spaceborne synthetic aperture radar (SAR) data from Envisat ASAR and Sentinel-1 in winter 2007 and 2018. Analysis of 2039 SAR images allowed identifying 4619 eddy signatures. The number of eddies detected per image per kilometer of MIZ length is similar for both years. Submesoscale and small mesoscale eddies dominate with cyclones detected twice more frequently than anticyclones. Eddy diameters range from 1 to 68 km with mean values of 6 km and 12 km over shallow and deep water, respectively. Mean eddy size grows with increasing ice concentration in the MIZ, yet most eddies are detected at the ice edge and where the ice concentration is below 20%. The fraction of sea ice trapped in cyclones (53%) is slightly higher than that in anticyclones (48%). The amount of sea ice trapped by a single ‘mean’ eddy is about 40 km2, while the average horizontal retreat of the ice edge due to eddy-induced ice melt is about 0.2–0.5 km·d–1 ± 0.02 km·d–1. Relation of eddy occurrence to background currents and winds is also discussed.

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