scholarly journals Small-scale sea ice deformation during N-ICE2015: From compact pack ice to marginal ice zone

2017 ◽  
Vol 122 (6) ◽  
pp. 5105-5120 ◽  
Author(s):  
Annu Oikkonen ◽  
Jari Haapala ◽  
Mikko Lensu ◽  
Juha Karvonen ◽  
Polona Itkin
Keyword(s):  
Sea Ice ◽  
Small Scale ◽  
Pack Ice ◽  
Marginal Ice Zone

scholarly journals Mapping and assessing variability in the Antarctic marginal ice zone, pack ice and coastal polynyas in two sea ice algorithms with implications on breeding success of snow petrels

2016 ◽  
Vol 10 (4) ◽  
pp. 1823-1843 ◽  
Author(s):  
Julienne C. Stroeve ◽  
Stephanie Jenouvrier ◽  
G. Garrett Campbell ◽  
Christophe Barbraud ◽  
Karine Delord
Keyword(s):  
Sea Ice ◽  
Breeding Success ◽  
Ice Cover ◽  
Passive Microwave ◽  
Phytoplankton Productivity ◽  
Pack Ice ◽  
Coastal Polynya ◽  
Marginal Ice Zone ◽  
Bootstrap Algorithm ◽  
The Antarctic

Abstract. Sea ice variability within the marginal ice zone (MIZ) and polynyas plays an important role for phytoplankton productivity and krill abundance. Therefore, mapping their spatial extent as well as seasonal and interannual variability is essential for understanding how current and future changes in these biologically active regions may impact the Antarctic marine ecosystem. Knowledge of the distribution of MIZ, consolidated pack ice and coastal polynyas in the total Antarctic sea ice cover may also help to shed light on the factors contributing towards recent expansion of the Antarctic ice cover in some regions and contraction in others. The long-term passive microwave satellite data record provides the longest and most consistent record for assessing the proportion of the sea ice cover that is covered by each of these ice categories. However, estimates of the amount of MIZ, consolidated pack ice and polynyas depend strongly on which sea ice algorithm is used. This study uses two popular passive microwave sea ice algorithms, the NASA Team and Bootstrap, and applies the same thresholds to the sea ice concentrations to evaluate the distribution and variability in the MIZ, the consolidated pack ice and coastal polynyas. Results reveal that the seasonal cycle in the MIZ and pack ice is generally similar between both algorithms, yet the NASA Team algorithm has on average twice the MIZ and half the consolidated pack ice area as the Bootstrap algorithm. Trends also differ, with the Bootstrap algorithm suggesting statistically significant trends towards increased pack ice area and no statistically significant trends in the MIZ. The NASA Team algorithm on the other hand indicates statistically significant positive trends in the MIZ during spring. Potential coastal polynya area and amount of broken ice within the consolidated ice pack are also larger in the NASA Team algorithm. The timing of maximum polynya area may differ by as much as 5 months between algorithms. These differences lead to different relationships between sea ice characteristics and biological processes, as illustrated here with the breeding success of an Antarctic seabird.

scholarly journals Differential Sea-Ice Drift. I. Spatial and Temporal Variations in Sea-Ice Deformation

1974 ◽  
Vol 13 (69) ◽  
pp. 437-455 ◽  
Author(s):  
W. D. Hibler ◽  
W. F. Weeks ◽  
A. Kovacs ◽  
S. F. Ackley
Keyword(s):  
Sea Ice ◽  
Strain Rate ◽  
Low Frequency ◽  
Temporal Variations ◽  
Small Scale ◽  
Strain Rate Tensor ◽  
Pack Ice ◽  
Average Strain Rate ◽  
Average Residual ◽  
Sea Ice Drift

Measurements of mesoscale sea-ice deformation over a region approximately 20 km in diameter were carried out over a five-week period in the spring of 1972 at the main AIDJEX camp in the Beaufort Sea. They have been analyzed to determine non-linearities in the ice velocity field (due to the discrete small-scale nature of the ice pack), as well as a continuum mode of deformation represented by a least-squares strain-rate tensor and vorticity. The deformation-rate time series between Julian day 88 and 112 exhibited net areal changes as large as 3% and deformation rates up to 0.16% per hour. In the principal axis co-ordinate system, the strain-rate typically exhibited a much larger compression (or extension) along one axis than along the other. Persistent cycles at ≈ 12 h wavelengths were observed in the divergence rate.A comparison of the average residual error with the average strain-rate magnitude indicated that strains measured on a scale of 10 km or greater can serve as a valid measure of the continuum motion of the sea ice. This conclusion is also substantiated by a comparison between the mesoscale deformation, and macroscale deformation measured over a ≈ 100 km diameter region.Regarding pack-ice rotation, vorticity calculations indicate that at low temporal frequencies (0.02 h−1), the whole mesoscale array rotates essentially as an entity and consequently the low-frequency vorticity can be estimated accurately from the rotation of a single floe.

scholarly journals The Use of Erts Photographs to Measure the Movement and Deformation of Sea Ice

1975 ◽  
Vol 15 (73) ◽  
pp. 429-436
Author(s):  
J. F. Nye
Keyword(s):  
Sea Ice ◽  
Continuum Model ◽  
Large Scale ◽  
Small Scale ◽  
Strain Rates ◽  
Pack Ice ◽  
Ice Velocity ◽  
Movement And Deformation ◽  
Preliminary Study ◽  
Displacement Measurements

AbstractIs it justified to adopt a two-dimensional continuum model for the movement and large-scale deformation of pack ice? A preliminary study oi’ ERTS-1 photography shows that the details of the ice movement are readily measurable; the problem is not in the accuracy of the remote sensing but in the inherent graininess of the sea ice. There is a spatial variation of ice velocity on a scale of several hundreds of kilometres; smaller-scale variations are superimposed on this, but their amplitude is not enough to obscure the large-scale trend. A continuum model is applicable, but, because of the small-scale variations in the velocity of the sea ice itself, it is not meaningful to specify continuum strain-rates on a scale of, say, 100 km to more than a certain accuracy, If ERTS pictures are available during the AIDJEX main experiment they could provide the necessary strain and displacement measurements for comparison with the predictions of the AIDJEX model.

scholarly journals Mapping and Assessing Variability in the Antarctic Marginal Ice Zone, the Pack Ice and Coastal Polynyas

2016 ◽  
Author(s):  
Julienne C. Stroeve ◽  
Stephanie Jenouvrier ◽  
G. Garrett Campbell ◽  
Christophe Barbraud ◽  
Karine Delord
Keyword(s):  
Sea Ice ◽  
Marine Ecosystem ◽  
Active Regions ◽  
Ice Cover ◽  
Passive Microwave ◽  
Phytoplankton Productivity ◽  
Pack Ice ◽  
Marginal Ice Zone ◽  
Data Record ◽  
The Antarctic

Abstract. Sea ice variability within the marginal ice zone (MIZ) and polynyas plays an important role for phytoplankton productivity and krill abundance. Therefore mapping their spatial extent, seasonal and interannual variability is essential for understanding how current and future changes in these biological active regions may impact the Antarctic marine ecosystem. Knowledge of the distribution of different ice types to the total Antarctic sea ice cover may also help to shed light on the factors contributing towards recent expansion of the Antarctic ice cover in some regions and contraction in others. The long-term passive microwave satellite data record provides the longest and most consistent data record for assessing different ice types. However, estimates of the amount of MIZ, consolidated pack ice and polynyas depends strongly on what sea ice algorithm is used. This study uses two popular passive microwave sea ice algorithms, the NASA Team and Bootstrap to evaluate the distribution and variability in the MIZ, the consolidated pack ice and coastal polynyas. Results reveal the NASA Team algorithm has on average twice the MIZ and half the consolidated pack ice area as the Bootstrap algorithm. Polynya area is also larger in the NASA Team algorithm, and the timing of maximum polynya area may differ by as much as 5 months between algorithms. These differences lead to different relationships between sea ice characteristics and biological processes, as illustrated here with the breeding success of an Antarctic seabird.

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 The Use of Erts Photographs to Measure the Movement and Deformation of Sea Ice

1975 ◽  
Vol 15 (73) ◽  
pp. 429-436 ◽  
Author(s):  
J. F. Nye
Keyword(s):  
Sea Ice ◽  
Continuum Model ◽  
Large Scale ◽  
Small Scale ◽  
Strain Rates ◽  
Pack Ice ◽  
Ice Velocity ◽  
Movement And Deformation ◽  
Preliminary Study ◽  
Displacement Measurements

Abstract Is it justified to adopt a two-dimensional continuum model for the movement and large-scale deformation of pack ice? A preliminary study oi’ ERTS-1 photography shows that the details of the ice movement are readily measurable; the problem is not in the accuracy of the remote sensing but in the inherent graininess of the sea ice. There is a spatial variation of ice velocity on a scale of several hundreds of kilometres; smaller-scale variations are superimposed on this, but their amplitude is not enough to obscure the large-scale trend. A continuum model is applicable, but, because of the small-scale variations in the velocity of the sea ice itself, it is not meaningful to specify continuum strain-rates on a scale of, say, 100 km to more than a certain accuracy, If ERTS pictures are available during the AIDJEX main experiment they could provide the necessary strain and displacement measurements for comparison with the predictions of the AIDJEX model.

scholarly journals Differential Sea-Ice Drift. I. Spatial and Temporal Variations in Sea-Ice Deformation

1974 ◽  
Vol 13 (69) ◽  
pp. 437-455 ◽  
Author(s):  
W. D. Hibler ◽  
W. F. Weeks ◽  
A. Kovacs ◽  
S. F. Ackley
Keyword(s):  
Sea Ice ◽  
Strain Rate ◽  
Low Frequency ◽  
Temporal Variations ◽  
Small Scale ◽  
Strain Rate Tensor ◽  
Pack Ice ◽  
Average Strain Rate ◽  
Average Residual ◽  
Sea Ice Drift

Measurements of mesoscale sea-ice deformation over a region approximately 20 km in diameter were carried out over a five-week period in the spring of 1972 at the main AIDJEX camp in the Beaufort Sea. They have been analyzed to determine non-linearities in the ice velocity field (due to the discrete small-scale nature of the ice pack), as well as a continuum mode of deformation represented by a least-squares strain-rate tensor and vorticity. The deformation-rate time series between Julian day 88 and 112 exhibited net areal changes as large as 3% and deformation rates up to 0.16% per hour. In the principal axis co-ordinate system, the strain-rate typically exhibited a much larger compression (or extension) along one axis than along the other. Persistent cycles at ≈ 12 h wavelengths were observed in the divergence rate.A comparison of the average residual error with the average strain-rate magnitude indicated that strains measured on a scale of 10 km or greater can serve as a valid measure of the continuum motion of the sea ice. This conclusion is also substantiated by a comparison between the mesoscale deformation, and macroscale deformation measured over a ≈ 100 km diameter region.Regarding pack-ice rotation, vorticity calculations indicate that at low temporal frequencies (0.02 h−1), the whole mesoscale array rotates essentially as an entity and consequently the low-frequency vorticity can be estimated accurately from the rotation of a single floe.

scholarly journals Meso- and microscale sea-ice motion in the East Siberian Sea as determined from ERS-1 SAR Data

1999 ◽  
Vol 45 (150) ◽  
pp. 370-383 ◽  
Author(s):  
Kim Morris ◽  
Shusun Li ◽  
Martin Jeffries
Keyword(s):  
Time Series ◽  
Sea Ice ◽  
Large Scale ◽  
Vector Fields ◽  
Lateral Displacement ◽  
Motion Vector ◽  
Sar Interferometry ◽  
East Siberian Sea ◽  
Pack Ice ◽  
Sar Data

Abstract Synthetic aperture radar- (SAR-)derived ice-motion vectors and SAR interferometry were used to study the sea-ice conditions in the region between the coast and 75° N (~ 560 km) in the East Siberian Sea in the vicinity of the Kolyma River. ERS-1 SAR data were acquired between 24 December 1993 and 30 March 1994 during the 3 day repeat Ice Phase of the satellite. The time series of the ice-motion vector fields revealed rapid (3 day) changes in the direction and displacement of the pack ice. Longer-term (≥ 1 month) trends also emerged which were related to changes in large-scale atmospheric circulation. On the basis of this time series, three sea-ice zones were identified: the near-shore, stationary-ice zone; a transitional-ice zone;and the pack-ice zone. Three 3 day interval and one 9 day interval interferometric sets (amplitude, correlation and phase diagrams) were generated for the end of December, the begining of February and mid-March. They revealed that the stationary-ice zone adjacent to the coast is in constant motion, primarily by lateral displacement, bending, tilting and rotation induced by atmospheric/oceanic forcing. The interferogram patterns change through time as the sea ice becomes thicker and a network of cracks becomes established in the ice cover. It was found that the major features in the interferograms were spatially correlated with sea-ice deformation features (cracks and ridges) and major discontinuities in ice thickness.

Pixel-scale evaluation of SSM/I sea-ice algorithms in the marginal ice zone during early fall freeze-up

2006 ◽  
Vol 20 (9) ◽  
pp. 1909-1927 ◽  
Author(s):  
Byong Jun Hwang ◽  
David G. Barber
Keyword(s):  
Sea Ice ◽  
Scale Evaluation ◽  
Marginal Ice Zone ◽  
Early Fall ◽  
Pixel Scale
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