scholarly journals Partial Shape Recognition for Sea Ice Motion Retrieval in the Marginal Ice Zone from Sentinel-1 and Sentinel-2

2021 ◽  
Vol 13 (21) ◽  
pp. 4473
Author(s):  
Mingfeng Wang ◽  
Marcel König ◽  
Natascha Oppelt
Keyword(s):  
Sea Ice ◽  
High Spatial Resolution ◽  
Shape Recognition ◽  
Ice Drift ◽  
Marginal Ice Zone ◽  
Motion Retrieval ◽  
Ice Floes ◽  
Low Sensitivity ◽  
Sequential Images ◽  
Sentinel 2

We present an algorithm for computing ice drift in the marginal ice zone (MIZ), based on partial shape recognition. With the high spatial resolution of Sentinel-1 and Sentinel-2 images, and the low sensitivity to atmospheric influences of Sentinel-1, a considerable quantity of ice floes is identified using a mathematical morphology method. Hausdorff distance is used to measure the similarity of segmented ice floes. It is tolerant to perturbations and deficiencies of floe shapes, which enhances the density of retrieved sea ice motion vectors. The PHD algorithm can be applied to sequential images from different sensors, and was tested on two combined image mosaics consisting of Sentinel-1 and Sentinel-2 data acquired over the Fram Strait; the PHD algorithm successfully produced pairs of matched ice floes. The matching result has been verified using shape and surface texture similarity of the ice floes. Moreover, the present method can naturally be extended to the problem of multi-source sea ice image registration.

scholarly journals Numerical Study on Wave-Ice Interaction in the Marginal Ice Zone

2020 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Tiecheng Wu ◽  
Wanzhen Luo ◽  
Dapeng Jiang ◽  
Rui Deng ◽  
Shuo Huang
Keyword(s):  
Sea Ice ◽  
Numerical Study ◽  
Test Results ◽  
Towing Tank ◽  
Marginal Ice Zone ◽  
Computational Fluid Dynamics Cfd ◽  
Numerical Research ◽  
Ice Floes ◽  
Cfd Method ◽  
Six Degree Of Freedom

The effect of waves on ice sheet is critical in the marginal ice zone (MIZ). Waves break large sea ice into small pieces and cause them to collide with each other. Simultaneously, the interaction between sea ice and waves attenuates these waves. In this study, a numerical research is conducted based on a computational fluid dynamics (CFD) method to investigate the response of single ice floe to wave action. The obtained results demonstrate that the sea ice has a violent six degree of freedom (6DoF) motion in waves. Ice floes with different sizes, thicknesses, and shapes exhibit different 6DoF motions under the action of waves. The heave and surge response amplitude operator (RAO) of the sea ice are related to wavelength. Furthermore, the overwash phenomenon can be observed in the simulation. The obtained results are compared with the model test in the towing tank based on artificial ice, and they agree well with test results.

scholarly journals Brief communication: Pancake ice floe size distribution during the winter expansion of the Antarctic marginal ice zone

2018 ◽  
Author(s):  
Alberto Alberello ◽  
Miguel Onorato ◽  
Luke Bennetts ◽  
Marcello Vichi ◽  
Clare Eayrs ◽  
...  
Keyword(s):  
Sea Ice ◽  
Size Distribution ◽  
Marginal Ice Zone ◽  
Ice Floes ◽  
The Antarctic

Abstract. The size distribution of pancake ice floes is calculated from images acquired during a voyage to the Antarctic marginal ice zone in the winter expansion season. Results show that 50 % of the sea ice area is made up by floes with diameters 2.3–4 m. The floe size distribution shows two distinct slopes on either side of the 2.3–4 m range. It is conjectured that growth of pancakes from frazil forms the distribution of small floes (D  4 m).

Interfacial generation of internal waves and turbulent heat flux due to enhanced inertial motion for deformed sea-ice floe: Preliminary results from MOSAiC expedition

2021 ◽  
Author(s):  
Yusuke Kawaguchi ◽  
Zoe Koenig ◽  
Mario Hoppman ◽  
Daiki Nomura ◽  
Mats Granskog ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Sea Ice ◽  
Internal Waves ◽  
Inertial Motion ◽  
Eddy Heat Flux ◽  
Ice Drift ◽  
Ice Floes ◽  
Ocean Boundary ◽  
Perennial Ice

<p>Sea-ice drift becomes most energetic at last moment in summer when refreezing is about to onset. Perennial ice floes, surviving over all seasons, tend to experience a number of deformation events over yearlong drift, with uneven distribution in thickness. Deformed ice floes protrude tall keels into water of ice-ocean boundary, and then stir it up. Consequently, combination of fast ice drift and deformation-experienced perennial ice could be a primary source of momentum/thermal energy for upper waters through propagation of internal waves. In this study, during MOSAiC expedition, we attempted to perform direct observation of wave generation in ice-ocean boundary layer underneath a drifting ice floe in the central Arctic Ocean. Time series of turbulent signals, represented by Reynolds stress <u'w'> and eddy heat flux <w'T'>, were obtained by an eddy covariance system (ECS), coupling a high-frequency (34 Hz) single-point current meter and a temperature sensor. Vertical/temporal properties of near-inertial waves were obtained by a downward-looking ADCP, collocated with ECS on the same ice floe. At same time, a triangle of high-precision GPS systems tracked ice movement to represent mean drift speed, rotation and deformation about the same floe seamlessly in time. Preliminary analyses of those combined data suggested that pronounced signals of inertial motion occurred in early September of 2020 as sheer ice keels dragged underlying waters, stratified by accumulation of melt water. It then allowed occurrence of near-inertial internal waves that tend to be trapped within the interfacial boundary layer, located within top 20 m. At the conference, we will present latest and quantitative knowledges from the MOSAiC expedition.</p>

Atmospheric drivers of a 4-month drift of an ice buoy in the Antarctic marginal ice zone

2021 ◽  
Author(s):  
Ashleigh Womack ◽  
Marcello Vichi
Keyword(s):  
Sea Ice ◽  
Atmospheric Forcing ◽  
Inertial Oscillations ◽  
Pass Filter ◽  
Atlantic Sector ◽  
Ice Drift ◽  
Marginal Ice Zone ◽  
Drift Conditions ◽  
The Antarctic ◽  
Lower Frequencies

<p>Sea-ice drift in the Antarctic marginal ice zone (MIZ) was investigated by using an ice buoy (buoy U1), deployed during the winter sea-ice expansion in July 2017, and drifted for approximately four months from the South Atlantic sector to the Indian Ocean sector of the Southern Ocean. The analysis of this buoy revealed that it remained within the MIZ even during the winter ice expansion, as the mixed pancake-frazil field was maintained. This allowed for a continued assumption of free drift conditions for buoy U1’s full drift, where it continued to respond linearly to the momentum transfer from surface winds. The analysis of buoy U1 also indicated a strong inertial signature at a period of 13.47 hours however, the wavelet analysis indicated majority of the power remained within the lower frequencies. This strong influence at the lower (multi-day) frequencies has therefore been identified as the primary effect of atmospheric forcing. When these lower frequencies were filtered out using the Butterworth high-pass filter it allowed the inertial oscillations to become more significant within the wavelet power spectrum, where it can be seen that these inertial oscillations were often triggered by the passage of cyclones. The initiation of inertial oscillations of sea ice has therefore been identified as the secondary effect of atmospheric forcing, which dominates ice drift at sub-daily timescales and results in the deviation of ice drift from a straight-line path. This comprehensive analysis suggests that the general concentration-based definition of the MIZ is not enough to describe the sea-ice cover, and that the MIZ, where sea ice is in free drift and under the influence of cyclone induced inertial motion, and presumably waves, extends up to »200 km.</p>

scholarly journals Characterizing sudden changes in Arctic sea ice drift and deformation on synoptic timescales

2016 ◽  
Author(s):  
Jennifer V. Lukovich ◽  
Cathleen A. Geiger ◽  
David G. Barber
Keyword(s):  
Sea Ice ◽  
Oil And Gas ◽  
Beaufort Sea ◽  
Arctic Sea Ice ◽  
Ice Drift ◽  
Shock Response ◽  
Near Shore ◽  
Sea Ice Drift ◽  
Ice Conditions ◽  
Ice Floes

Abstract. In this study, we develop a framework for the assessment of sudden changes in sea ice drift and associated deformation processes in response to atmospheric forcing and ice–coastal interactions, based on analysis of ice buoy triplet centroids and areas. Examined in particular is the spatiotemporal evolution in sea ice floes that are tracked with GPS beacons deployed in triplets in the southern Beaufort Sea at varying distances from the coastline in fall, 2009 – triplets A to D, with A (D) located closest to (furthest from) the coastline. This study illustrates the use of shock-response diagnostics to evaluate eight identified sudden changes or shock events on daily timescales. Results from this analysis show that shock events in the southern Beaufort Sea occur in at least one of two forms: (1) during a reversal in winds, or (2) sustained north/easterly winds, with response mechanisms governed by ice conditions and interactions with the coastline. Demonstrated also is the emergence of a shear-shock event (SSE) that results in reduced ice concentrations for triplets B, C, and D, one, three and five days following the SSE, respectively and loss of synchronicity in ice-atmosphere interactions. The tools developed in this study provide a unique characterization of sea ice dynamical processes in the southern Beaufort Sea, with implications for quantifying "shock-response" systems relevant for ice hazard assessments and forecasting applications required by oil and gas, marine transportation, and indigenous use of near shore Arctic areas.

scholarly journals A Computational Fluid Dynamics Model for the Small-Scale Dynamics of Wave, Ice Floe and Interstitial Grease Ice Interaction

Fluids ◽  
2021 ◽  
Vol 6 (5) ◽  
pp. 176
Author(s):  
Rutger Marquart ◽  
Alfred Bogaers ◽  
Sebastian Skatulla ◽  
Alberto Alberello ◽  
Alessandro Toffoli ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Sea Ice ◽  
Strain Rate ◽  
Large Scale ◽  
Ocean Waves ◽  
Small Scale ◽  
Drag Forces ◽  
Marginal Ice Zone ◽  
Ice Floes

The marginal ice zone is a highly dynamical region where sea ice and ocean waves interact. Large-scale sea ice models only compute domain-averaged responses. As the majority of the marginal ice zone consists of mobile ice floes surrounded by grease ice, finer-scale modelling is needed to resolve variations of its mechanical properties, wave-induced pressure gradients and drag forces acting on the ice floes. A novel computational fluid dynamics approach is presented that considers the heterogeneous sea ice material composition and accounts for the wave-ice interaction dynamics. Results show, after comparing three realistic sea ice layouts with similar concentration and floe diameter, that the discrepancy between the domain-averaged temporal stress and strain rate evolutions increases for decreasing wave period. Furthermore, strain rate and viscosity are mostly affected by the variability of ice floe shape and diameter.

scholarly journals 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

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.

scholarly journals Brief communication: Pancake ice floe size distribution during the winter expansion of the Antarctic marginal ice zone

2019 ◽  
Vol 13 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Alberto Alberello ◽  
Miguel Onorato ◽  
Luke Bennetts ◽  
Marcello Vichi ◽  
Clare Eayrs ◽  
...  
Keyword(s):  
Sea Ice ◽  
Size Distribution ◽  
Power Law ◽  
Marginal Ice Zone ◽  
Ice Floes ◽  
The Antarctic

Abstract. The size distribution of pancake ice floes is calculated from images acquired during a voyage to the Antarctic marginal ice zone in the winter expansion season. Results show that 50 % of the sea ice area is made up of floes with diameters of 2.3–4 m. The floe size distribution shows two distinct slopes on either side of the 2.3–4 m range, neither of which conforms to a power law. Following a relevant recent study, it is conjectured that the growth of pancakes from frazil forms the distribution of small floes (D<2.3 m), and welding of pancakes forms the distribution of large floes (D>4 m).

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