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Rudiger Gerdes - One of the best experts on this subject based on the ideXlab platform.
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Empirical error functions for monthly mean Arctic sea‐Ice Drift
Journal of Geophysical Research, 2015Co-Authors: Hiroshi Sumata, Rudiger Gerdes, Frank Kauker, Michael KarcherAbstract:Empirical error functions for 6 different low-resolution Arctic sea-Ice Drift products are presented on monthly time-scales. To assess the error statistics of the Eulerian Ice-Drift products, we use high-resolution Lagrangian sea-Ice Drift obtained from synthetic aperture radar (SAR) images. We processed the Lagrangian Drift to Eulerian Drift vectors and used them as a reference for the error assessment. Unlike sea-Ice buoy trajectory data traditionally used for that purpose, SAR offers a much larger number of data, which enables us to do a thorough assessment of the error statistics of the Eulerian products under different Ice conditions. We find that the error statistics differ between the products and between the seasons. For some products the error is dependent on Ice Drift speed, while for others the error is rather dependent on Ice concentration or on both. The summer Ice Drifts have roughly a two times larger error than the winter Drifts, and show significant mean biases. The calculated empirical error functions allow us to derive uncertainty maps for the respective products. These maps can be used for model validation and data assimilation.
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empirical error functions for monthly mean arctic sea Ice Drift
Journal of Geophysical Research, 2015Co-Authors: Hiroshi Sumata, Rudiger Gerdes, Frank Kauker, Michael KarcherAbstract:Empirical error functions for 6 different low-resolution Arctic sea-Ice Drift products are presented on monthly time-scales. To assess the error statistics of the Eulerian Ice-Drift products, we use high-resolution Lagrangian sea-Ice Drift obtained from synthetic aperture radar (SAR) images. We processed the Lagrangian Drift to Eulerian Drift vectors and used them as a reference for the error assessment. Unlike sea-Ice buoy trajectory data traditionally used for that purpose, SAR offers a much larger number of data, which enables us to do a thorough assessment of the error statistics of the Eulerian products under different Ice conditions. We find that the error statistics differ between the products and between the seasons. For some products the error is dependent on Ice Drift speed, while for others the error is rather dependent on Ice concentration or on both. The summer Ice Drifts have roughly a two times larger error than the winter Drifts, and show significant mean biases. The calculated empirical error functions allow us to derive uncertainty maps for the respective products. These maps can be used for model validation and data assimilation.
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uncertainty of arctic summer Ice Drift assessed by high resolution sar data
Journal of Geophysical Research, 2015Co-Authors: Hiroshi Sumata, R Kwok, Rudiger Gerdes, Frank Kauker, Michael KarcherAbstract:Time-space varying uncertainty maps of monthly mean Arctic summer Ice Drift are presented. To assess the error statistics of two low-resolution Eulerian Ice Drift products, we use high-resolution Lagrangian Ice motion derived from synthetic aperture radar (SAR) imagery. The Lagrangian trajectories from the SAR data are converted to an Eulerian format to serve as reference for the error assessment of the Eulerian products. The statistical error associated with the conversion is suppressed to an acceptable level by applying a threshold for averaging. By using the SAR Ice Drift as a reference, we formulate the uncertainty of monthly mean Ice Drift as an empirical function of Drift speed and Ice concentration. The empirical functions are applied to derive uncertainty maps of Arctic Ice Drift fields. The estimated uncertainty maps reasonably capture an increase of uncertainty with the progress of summer melting season. The uncertainties range from 1.0 cm s−1 to 2.0 cm s−1, which indicates that the low-resolution Eulerian products for summer seasons are of practical use for climate studies, model validation and data assimilation, if their uncertainties are appropriately taken into account.
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an intercomparison of arctic Ice Drift products to deduce uncertainty estimates
Journal of Geophysical Research, 2014Co-Authors: Hiroshi Sumata, Frank Kauker, Michael Karcher, Thomas Lavergne, Fanny Girardardhuin, Noriaki Kimura, Mark Tschudi, Rudiger GerdesAbstract:An intercomparison of four low-resolution remotely sensed Ice-Drift products in the Arctic Ocean is presented. The purpose of the study is to examine the uncertainty in space and time of these different Drift products. The comparison is based on monthly mean Ice Drifts from October 2002 to December 2006. The Ice Drifts were also compared with available buoy data. The result shows that the differences of the Drift vectors are not spatially uniform, but are covariant with Ice concentration and thickness. In high (low) Ice-concentration areas, the differences are small (large), and in thick (thin) Ice-thickness areas, the differences are small (large). A comparison with the Drift deduced from buoys reveals that the error of the Drift speed depends on the magnitude of the Drift speed: larger Drift speeds have larger errors. Based on the intercomparison of the products and comparison with buoy data, uncertainties of the monthly mean Drift are estimated. The estimated uncertainty maps reasonably reflect the difference between the products in relation to Ice concentration and the bias from the buoy Drift in relation to Drift speed. Examinations of distinctive features of Arctic sea Ice motion demonstrate that the transpolar Drift speed differs among the products by 13% (0.32 cm s−1) on average, and Ice Drift curl in the Amerasian Basin differs by up to 24% (3.3 × 104 m2 s−1). These uncertainties should be taken into account if these products are used, particularly for model validation and data assimilation within the Arctic.
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validating satellite derived and modelled sea Ice Drift in the laptev sea with in situ measurements from the winter of 2007 2008
Polar Research, 2011Co-Authors: Polona Rozman, Rudiger Gerdes, Jens Holemann, Thomas Krumpen, Cornelia Koberle, Thomas Lavergne, Susanne Adams, Fanny GirardardhuinAbstract:A correct representation of the Ice movement in an Arctic sea-Ice-ocean coupled model is essential for a realistic sea-Ice and ocean simulation. The aim of this study is to validate the observational and simulated sea-Ice Drift for the Laptev Sea Shelf region with in situ measurements from the winter of 2007/08. Several satellite remote-sensing data sets are first compared to mooring measurements and afterwards to the sea-Ice Drift simulated by the coupled sea-Ice-ocean model. The different satellite products have a correlation to the in situ data ranging from 0.56 to 0.86. The correlations of sea-Ice direction or individual Drift vector components between the in situ data and the observations are high, about 0.8. Similar correlations are achieved by the model simulations. The sea-Ice Drift speed derived from the model and from some satellite products have only moderate correlations of about 0.6 to the in situ record. The standard errors for the satellite products and model simulations Drift components are similar to the errors of the satellite products in the central Arctic and are about 0.03 m/s. The fast-Ice parameterization implementation in the model was also successfully tested for its influence on the sea-Ice Drift. In contrast to the satellite products, the model Drift simulations have a full temporal and spatial coverage and results are reliable enough to use as sea-Ice Drift estimates on the Laptev Sea Shelf.
Michael Karcher - One of the best experts on this subject based on the ideXlab platform.
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Empirical error functions for monthly mean Arctic sea‐Ice Drift
Journal of Geophysical Research, 2015Co-Authors: Hiroshi Sumata, Rudiger Gerdes, Frank Kauker, Michael KarcherAbstract:Empirical error functions for 6 different low-resolution Arctic sea-Ice Drift products are presented on monthly time-scales. To assess the error statistics of the Eulerian Ice-Drift products, we use high-resolution Lagrangian sea-Ice Drift obtained from synthetic aperture radar (SAR) images. We processed the Lagrangian Drift to Eulerian Drift vectors and used them as a reference for the error assessment. Unlike sea-Ice buoy trajectory data traditionally used for that purpose, SAR offers a much larger number of data, which enables us to do a thorough assessment of the error statistics of the Eulerian products under different Ice conditions. We find that the error statistics differ between the products and between the seasons. For some products the error is dependent on Ice Drift speed, while for others the error is rather dependent on Ice concentration or on both. The summer Ice Drifts have roughly a two times larger error than the winter Drifts, and show significant mean biases. The calculated empirical error functions allow us to derive uncertainty maps for the respective products. These maps can be used for model validation and data assimilation.
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empirical error functions for monthly mean arctic sea Ice Drift
Journal of Geophysical Research, 2015Co-Authors: Hiroshi Sumata, Rudiger Gerdes, Frank Kauker, Michael KarcherAbstract:Empirical error functions for 6 different low-resolution Arctic sea-Ice Drift products are presented on monthly time-scales. To assess the error statistics of the Eulerian Ice-Drift products, we use high-resolution Lagrangian sea-Ice Drift obtained from synthetic aperture radar (SAR) images. We processed the Lagrangian Drift to Eulerian Drift vectors and used them as a reference for the error assessment. Unlike sea-Ice buoy trajectory data traditionally used for that purpose, SAR offers a much larger number of data, which enables us to do a thorough assessment of the error statistics of the Eulerian products under different Ice conditions. We find that the error statistics differ between the products and between the seasons. For some products the error is dependent on Ice Drift speed, while for others the error is rather dependent on Ice concentration or on both. The summer Ice Drifts have roughly a two times larger error than the winter Drifts, and show significant mean biases. The calculated empirical error functions allow us to derive uncertainty maps for the respective products. These maps can be used for model validation and data assimilation.
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uncertainty of arctic summer Ice Drift assessed by high resolution sar data
Journal of Geophysical Research, 2015Co-Authors: Hiroshi Sumata, R Kwok, Rudiger Gerdes, Frank Kauker, Michael KarcherAbstract:Time-space varying uncertainty maps of monthly mean Arctic summer Ice Drift are presented. To assess the error statistics of two low-resolution Eulerian Ice Drift products, we use high-resolution Lagrangian Ice motion derived from synthetic aperture radar (SAR) imagery. The Lagrangian trajectories from the SAR data are converted to an Eulerian format to serve as reference for the error assessment of the Eulerian products. The statistical error associated with the conversion is suppressed to an acceptable level by applying a threshold for averaging. By using the SAR Ice Drift as a reference, we formulate the uncertainty of monthly mean Ice Drift as an empirical function of Drift speed and Ice concentration. The empirical functions are applied to derive uncertainty maps of Arctic Ice Drift fields. The estimated uncertainty maps reasonably capture an increase of uncertainty with the progress of summer melting season. The uncertainties range from 1.0 cm s−1 to 2.0 cm s−1, which indicates that the low-resolution Eulerian products for summer seasons are of practical use for climate studies, model validation and data assimilation, if their uncertainties are appropriately taken into account.
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an intercomparison of arctic Ice Drift products to deduce uncertainty estimates
Journal of Geophysical Research, 2014Co-Authors: Hiroshi Sumata, Frank Kauker, Michael Karcher, Thomas Lavergne, Fanny Girardardhuin, Noriaki Kimura, Mark Tschudi, Rudiger GerdesAbstract:An intercomparison of four low-resolution remotely sensed Ice-Drift products in the Arctic Ocean is presented. The purpose of the study is to examine the uncertainty in space and time of these different Drift products. The comparison is based on monthly mean Ice Drifts from October 2002 to December 2006. The Ice Drifts were also compared with available buoy data. The result shows that the differences of the Drift vectors are not spatially uniform, but are covariant with Ice concentration and thickness. In high (low) Ice-concentration areas, the differences are small (large), and in thick (thin) Ice-thickness areas, the differences are small (large). A comparison with the Drift deduced from buoys reveals that the error of the Drift speed depends on the magnitude of the Drift speed: larger Drift speeds have larger errors. Based on the intercomparison of the products and comparison with buoy data, uncertainties of the monthly mean Drift are estimated. The estimated uncertainty maps reasonably reflect the difference between the products in relation to Ice concentration and the bias from the buoy Drift in relation to Drift speed. Examinations of distinctive features of Arctic sea Ice motion demonstrate that the transpolar Drift speed differs among the products by 13% (0.32 cm s−1) on average, and Ice Drift curl in the Amerasian Basin differs by up to 24% (3.3 × 104 m2 s−1). These uncertainties should be taken into account if these products are used, particularly for model validation and data assimilation within the Arctic.
R Kwok - One of the best experts on this subject based on the ideXlab platform.
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sea Ice Drift in the southern ocean regional patterns variability and trends
Elementa: Science of the Anthropocene, 2017Co-Authors: R Kwok, Shirley S Pang, Sahra KacimiAbstract:Understanding long-term changes in large-scale sea Ice Drift in the Southern Ocean is of considerable interest given its contribution to Ice extent, to Ice production in open waters, with associated dense water formation and heat flux to the atmosphere, and thus to the climate system. In this paper, we examine the trends and variability of this Ice Drift in a 34-year record (1982–2015) derived from satellite observations. Uncertainties in Drift (~3 to 4 km day –1 ) were assessed with higher resolution observations. In a linear model, Drift speeds were ~1.4% of the geostrophic wind from reanalyzed sea-level pressure, nearly 50% higher than that of the Arctic. This result suggests an Ice cover in the Southern Ocean that is thinner, weaker, and less compact. Geostrophic winds explained all but ~40% of the variance in Ice Drift. Three spatially distinct Drift patterns were shown to be controlled by the location and depth of atmospheric lows centered over the Amundsen, Riiser-Larsen, and Davis seas. Positively correlated changes in sea-level pressures at the three centers (up to 0.64) suggest correlated changes in the wind-driven Drift patterns. Seasonal trends in Ice edge are linked to trends in meridional winds and also to on-Ice/off-Ice trends in zonal winds, due to zonal asymmetry of the Antarctic Ice cover. Sea Ice area export at flux gates that parallel the 1000‐m isobath were extended to cover the 34-year record. Interannual variability in Ice export in the Ross and Weddell seas linked to the depth and location of the Amundsen Sea and Riiser-Larsen Sea lows to their east. Compared to shorter records, where there was a significant positive trend in Ross Sea Ice area flux, the longer 34-year trends of outflow from both seas are now statistically insignificant. Copyright: © 2017 California Institute of Technology. U.S. Government sponsorship acknowledged.
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uncertainty of arctic summer Ice Drift assessed by high resolution sar data
Journal of Geophysical Research, 2015Co-Authors: Hiroshi Sumata, R Kwok, Rudiger Gerdes, Frank Kauker, Michael KarcherAbstract:Time-space varying uncertainty maps of monthly mean Arctic summer Ice Drift are presented. To assess the error statistics of two low-resolution Eulerian Ice Drift products, we use high-resolution Lagrangian Ice motion derived from synthetic aperture radar (SAR) imagery. The Lagrangian trajectories from the SAR data are converted to an Eulerian format to serve as reference for the error assessment of the Eulerian products. The statistical error associated with the conversion is suppressed to an acceptable level by applying a threshold for averaging. By using the SAR Ice Drift as a reference, we formulate the uncertainty of monthly mean Ice Drift as an empirical function of Drift speed and Ice concentration. The empirical functions are applied to derive uncertainty maps of Arctic Ice Drift fields. The estimated uncertainty maps reasonably capture an increase of uncertainty with the progress of summer melting season. The uncertainties range from 1.0 cm s−1 to 2.0 cm s−1, which indicates that the low-resolution Eulerian products for summer seasons are of practical use for climate studies, model validation and data assimilation, if their uncertainties are appropriately taken into account.
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trends in arctic sea Ice Drift and role of wind forcing 1992 2009
Geophysical Research Letters, 2011Co-Authors: Gunnar Spreen, R Kwok, Dimitris MenemenlisAbstract:[1] We examine the spatial trends in Arctic sea Ice Drift speed from satellite data and the role of wind forcing for the winter months of October through May. Between 1992 and 2009, the spatially averaged trend in Drift speed within the Arctic Basin is 10.6% ± 0.9%/decade, and ranges between −4% and 16%/decade depending on the location. The mean trend is dominated by the second half of the period. In fact, for the five years after a clear break point in March 2004, the average trend increased to 46% ± 5%/decade. Over the 1992–2009 period, averaged trends of wind speed from four atmospheric reanalyses are only 1% to 2%/decade. Regionally, positive trends in wind speed (of up to 9%/decade) are seen over a large fraction of the Central Arctic, where the trends in Drift speeds are highest. Spatial correlations between the basin-wide trends in wind and Drift speeds are moderate (between 0.40 and 0.52). Our results suggest that changes in wind speed explain a fraction of the observed increase in Drift speeds in the Central Arctic but not over the entire basin. In other regions thinning of the Ice cover is a more likely cause of the increase in Ice Drift speed.
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baffin bay Ice Drift and export 2002 2007
Geophysical Research Letters, 2007Co-Authors: R KwokAbstract:[1] Multiyear estimates of sea Ice Drift in Baffin Bay and Davis Strait are derived for the first time from the 89 GHz channel of the AMSR-E instrument. Uncertainties in the Drift estimates, assessed with Envisat Ice motion, are ∼2–3 km/day. A persistent atmospheric trough, between the coast of Greenland and Baffin Island, drives the prevailing southward Drift pattern with average daily displacements in excess of 18–20 km during winter. Over the 5-year record, the Ice export ranges between 360 and 675 × 103 km2, with an average of 530 × 103 km2. Sea Ice area inflow from the Nares Strait, Lancaster Sound and Jones Sound potentially contribute up to a third of the net area outflow while Ice production at the North Water Polynya contributes the balance. Rough estimates of annual volume export give ∼500–800 km3. Comparatively, these are ∼70% and ∼30% of the annual area and volume exports at the Fram Strait.
Hiroshi Sumata - One of the best experts on this subject based on the ideXlab platform.
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Empirical error functions for monthly mean Arctic sea‐Ice Drift
Journal of Geophysical Research, 2015Co-Authors: Hiroshi Sumata, Rudiger Gerdes, Frank Kauker, Michael KarcherAbstract:Empirical error functions for 6 different low-resolution Arctic sea-Ice Drift products are presented on monthly time-scales. To assess the error statistics of the Eulerian Ice-Drift products, we use high-resolution Lagrangian sea-Ice Drift obtained from synthetic aperture radar (SAR) images. We processed the Lagrangian Drift to Eulerian Drift vectors and used them as a reference for the error assessment. Unlike sea-Ice buoy trajectory data traditionally used for that purpose, SAR offers a much larger number of data, which enables us to do a thorough assessment of the error statistics of the Eulerian products under different Ice conditions. We find that the error statistics differ between the products and between the seasons. For some products the error is dependent on Ice Drift speed, while for others the error is rather dependent on Ice concentration or on both. The summer Ice Drifts have roughly a two times larger error than the winter Drifts, and show significant mean biases. The calculated empirical error functions allow us to derive uncertainty maps for the respective products. These maps can be used for model validation and data assimilation.
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empirical error functions for monthly mean arctic sea Ice Drift
Journal of Geophysical Research, 2015Co-Authors: Hiroshi Sumata, Rudiger Gerdes, Frank Kauker, Michael KarcherAbstract:Empirical error functions for 6 different low-resolution Arctic sea-Ice Drift products are presented on monthly time-scales. To assess the error statistics of the Eulerian Ice-Drift products, we use high-resolution Lagrangian sea-Ice Drift obtained from synthetic aperture radar (SAR) images. We processed the Lagrangian Drift to Eulerian Drift vectors and used them as a reference for the error assessment. Unlike sea-Ice buoy trajectory data traditionally used for that purpose, SAR offers a much larger number of data, which enables us to do a thorough assessment of the error statistics of the Eulerian products under different Ice conditions. We find that the error statistics differ between the products and between the seasons. For some products the error is dependent on Ice Drift speed, while for others the error is rather dependent on Ice concentration or on both. The summer Ice Drifts have roughly a two times larger error than the winter Drifts, and show significant mean biases. The calculated empirical error functions allow us to derive uncertainty maps for the respective products. These maps can be used for model validation and data assimilation.
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uncertainty of arctic summer Ice Drift assessed by high resolution sar data
Journal of Geophysical Research, 2015Co-Authors: Hiroshi Sumata, R Kwok, Rudiger Gerdes, Frank Kauker, Michael KarcherAbstract:Time-space varying uncertainty maps of monthly mean Arctic summer Ice Drift are presented. To assess the error statistics of two low-resolution Eulerian Ice Drift products, we use high-resolution Lagrangian Ice motion derived from synthetic aperture radar (SAR) imagery. The Lagrangian trajectories from the SAR data are converted to an Eulerian format to serve as reference for the error assessment of the Eulerian products. The statistical error associated with the conversion is suppressed to an acceptable level by applying a threshold for averaging. By using the SAR Ice Drift as a reference, we formulate the uncertainty of monthly mean Ice Drift as an empirical function of Drift speed and Ice concentration. The empirical functions are applied to derive uncertainty maps of Arctic Ice Drift fields. The estimated uncertainty maps reasonably capture an increase of uncertainty with the progress of summer melting season. The uncertainties range from 1.0 cm s−1 to 2.0 cm s−1, which indicates that the low-resolution Eulerian products for summer seasons are of practical use for climate studies, model validation and data assimilation, if their uncertainties are appropriately taken into account.
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an intercomparison of arctic Ice Drift products to deduce uncertainty estimates
Journal of Geophysical Research, 2014Co-Authors: Hiroshi Sumata, Frank Kauker, Michael Karcher, Thomas Lavergne, Fanny Girardardhuin, Noriaki Kimura, Mark Tschudi, Rudiger GerdesAbstract:An intercomparison of four low-resolution remotely sensed Ice-Drift products in the Arctic Ocean is presented. The purpose of the study is to examine the uncertainty in space and time of these different Drift products. The comparison is based on monthly mean Ice Drifts from October 2002 to December 2006. The Ice Drifts were also compared with available buoy data. The result shows that the differences of the Drift vectors are not spatially uniform, but are covariant with Ice concentration and thickness. In high (low) Ice-concentration areas, the differences are small (large), and in thick (thin) Ice-thickness areas, the differences are small (large). A comparison with the Drift deduced from buoys reveals that the error of the Drift speed depends on the magnitude of the Drift speed: larger Drift speeds have larger errors. Based on the intercomparison of the products and comparison with buoy data, uncertainties of the monthly mean Drift are estimated. The estimated uncertainty maps reasonably reflect the difference between the products in relation to Ice concentration and the bias from the buoy Drift in relation to Drift speed. Examinations of distinctive features of Arctic sea Ice motion demonstrate that the transpolar Drift speed differs among the products by 13% (0.32 cm s−1) on average, and Ice Drift curl in the Amerasian Basin differs by up to 24% (3.3 × 104 m2 s−1). These uncertainties should be taken into account if these products are used, particularly for model validation and data assimilation within the Arctic.
Petra Heil - One of the best experts on this subject based on the ideXlab platform.
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tidal forcing on sea Ice Drift and deformation in the western weddell sea in early austral summer 2004
Deep-sea Research Part Ii-topical Studies in Oceanography, 2008Co-Authors: Petra Heil, Jouko Launiainen, Christian Haas, Jennifer K Hutchings, A P Worby, Milla M Johansson, W D HiblerAbstract:Abstract Sea-Ice Drift and deformation in the western Weddell Sea in early austral summer of 2004 are characterised using in situ data from a meso-scale array of 24 Drifting Ice buoys. Horizontal GPS-derived position measurements are available from Drifting buoys deployed as part of the Ice Station POLarstern [ISPOL] experiment for 26 days during late November and December 2004, at various temporal resolutions and spatial accuracies. These data form the basis for sea-Ice velocity and deformation measurements across the meso-scale ISPOL array and at two remote sites. Analysis of the sea-Ice velocities reveals coherence for sea-Ice Drift at separations of less than 70 km; and a correlation length scale of 60 km. Within the limits of the ISPOL array, at larger separations zonal Ice Drift remains correlated, while meridional Ice Drift becomes uncorrelated. This together with the east–west gradient in Ice velocities indicates the influence of bathymetry, via tidal forcing, on local dynamic processes. Atmospheric forcing also contributes to the sea-Ice Drift: about 40% of variability in the sea-Ice velocity is explained by changes in wind velocity, which is significantly less than other studies have found for the region during winter. Sea-Ice deformation has been derived for the overall array and four sub-arrays. There appeared to be no spatial scale dependency of Ice deformation, although considerable spatial variability was observed between sub-arrays. The net divergence of the ISPOL array was in excess of 30%, with the largest contributions to divergence being from the southern section and along the eastern side of the overall ISPOL array. Temporal variability for all deformation parameters is dominated by high-frequency (sub-daily) processes, namely tidal forcing and inertial response. Low-frequency (multiple days) processes, including atmospheric changes, played a secondary role in forcing sea-Ice deformation during ISPOL.
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the pattern and variability of antarctic sea Ice Drift in the indian ocean and western pacific sectors
Journal of Geophysical Research, 1999Co-Authors: Petra Heil, Ian AllisonAbstract:Sea-Ice Drift physically redistributes pack Ice and changes Ice extent, concentration, and, through deformation, the Ice-thickness distribution. In this paper, data are presented from 39 satellite-tracked buoys, deployed during various seasons from 1985 to 1996 in the sea Ice of the Southern Ocean off East Antarctica between 20° and 160°E longitude. The dominant features of the Ice motion in the region are a westward Drift parallel to the bathymetry near the Antarctic continent, a cyclonic circulation cell in Prydz Bay, and eastward Drift of the Ice to the north of the zonal shear zone. The oceanic circulation along the coast is generally barotropic and the Ice Drift is well correlated with bottom topography. Northward outflows, the locations of which are determined by both bottom topography and the seasonally varying position of the zonal shear zone, allow the discharge of sea Ice from the westward Drift in the south into the northerly belt of eastward flow, but with considerable variability in the net northward Ice transport. The Ice translation monitored by the buoys is used to derive the spatial pattern of the Ice-velocity field. The daily average Ice-Drift speed in the westward flow is 0.23 m s−1 (19.8 km d−1), with considerable spatial and temporal variability, and in the eastward flow the average is 0.17 m s−1 (15.1 km d−1). Seasonal and interannual Ice-Drift variabilities are analyzed. The results are compared with satellite data of sea-Ice extent and concentration over the same time, as well as with hydrographic observation of the position of the Antarctic Divergence.
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The pattern and variability of Antarctic sea‐Ice Drift in the Indian Ocean and western Pacific sectors
Journal of Geophysical Research, 1999Co-Authors: Petra Heil, Ian AllisonAbstract:Sea-Ice Drift physically redistributes pack Ice and changes Ice extent, concentration, and, through deformation, the Ice-thickness distribution. In this paper, data are presented from 39 satellite-tracked buoys, deployed during various seasons from 1985 to 1996 in the sea Ice of the Southern Ocean off East Antarctica between 20° and 160°E longitude. The dominant features of the Ice motion in the region are a westward Drift parallel to the bathymetry near the Antarctic continent, a cyclonic circulation cell in Prydz Bay, and eastward Drift of the Ice to the north of the zonal shear zone. The oceanic circulation along the coast is generally barotropic and the Ice Drift is well correlated with bottom topography. Northward outflows, the locations of which are determined by both bottom topography and the seasonally varying position of the zonal shear zone, allow the discharge of sea Ice from the westward Drift in the south into the northerly belt of eastward flow, but with considerable variability in the net northward Ice transport. The Ice translation monitored by the buoys is used to derive the spatial pattern of the Ice-velocity field. The daily average Ice-Drift speed in the westward flow is 0.23 m s−1 (19.8 km d−1), with considerable spatial and temporal variability, and in the eastward flow the average is 0.17 m s−1 (15.1 km d−1). Seasonal and interannual Ice-Drift variabilities are analyzed. The results are compared with satellite data of sea-Ice extent and concentration over the same time, as well as with hydrographic observation of the position of the Antarctic Divergence.
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The pattern and variability of Antarctic sea-Ice Drift in the Indian Ocean and western Pacific sectors
Journal of Geophysical Research, 1999Co-Authors: Petra Heil, Ian AllisonAbstract:Sea - Ice Drift physically redistributes pack Ice and changes Ice extent, concentration, and, through deformation, the Ice -thickness distribution. In this paper, data are presented from 39 satellite-tracked buoys, deployed during various seasons from 1985 to 1996 in the sea ...
