Ng, Felix S L (2015): Planimetric ice-flow convergence and flow-orthonormal strain rate across the Antarctic Ice Sheet, with links to model result files [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.841137, Supplement to: Ng, FSL (2015): Spatial complexity of ice flow across the Antarctic Ice Sheet. Nature Geoscience, 8(10), https://doi.org/10.1038/ngeo2532
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Abstract:
Fast-flowing ice streams discharge most of the ice from the interior of the Antarctic Ice Sheet coastward. Understanding how their tributary organisation is governed and evolves is essential for developing reliable models of the ice sheet's response to climate change. Despite much research on ice-stream mechanics, this problem is unsolved, because the complexity of flow within and across the tributary networks has hardly been interrogated. Here I present the first map of planimetric flow convergence across the ice sheet, calculated from satellite measurements of ice surface velocity, and use it to explore this complexity. The convergence map of Antarctica elucidates how ice-stream tributaries draw ice from the interior. It also reveals curvilinear zones of convergence along lateral shear margins of streaming, and abundant convergence ripples associated with nonlinear ice rheology and changes in bed topography and friction. Flow convergence on ice-stream tributaries and their feeding zones is markedly uneven, and interspersed with divergence at distances of the order of kilometres. For individual drainage basins as well as the ice sheet as a whole, the range of convergence and divergence decreases systematically with flow speed, implying that fast flow cannot converge or diverge as much as slow flow. I therefore deduce that flow in ice-stream networks is subject to mechanical regulation that limits flow-orthonormal strain rates. These properties and the gridded data of convergence and flow-orthonormal strain rate in this archive provide targets for ice- sheet simulations and motivate more research into the origin and dynamics of tributarization.
Further details:
Coverage:
Latitude: -90.000000 * Longitude: 0.000000
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | File content | Content | Ng, Felix S L | |||
| 2 | File name | File name | Ng, Felix S L | |||
| 3 | File format | File format | Ng, Felix S L | |||
| 4 | Uniform resource locator/link to model result file | URL model | Ng, Felix S L | |||
| 5 | File size | File size | kByte | Ng, Felix S L |
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
40 data points
Data
| 1 Content | 2 File name | 3 File format | 4 URL model | 5 File size [kByte] |
|---|---|---|---|---|
| kriged estimates of ice-flow convergence, C (per km) | ascii_CK0 | ArcGIS ASCII Raster format | ascii_CK0.zip | 195338 |
| kriging standard deviation sigma_c of errors in the ice-flow convergence estimates (per km) | ascii_CS | ArcGIS ASCII Raster format | ascii_CS.zip | 108520 |
| flow-orthonormal strain rate (per yr) | ascii_SR | ArcGIS ASCII Raster format | ascii_SR.zip | 205154 |
| kriged estimates of ice-flow direction, theta_K (radian) | ascii_thetaK | ArcGIS ASCII Raster format | ascii_thetaK.zip | 155882 |
| kriging standard deviation sigma_theta of errors in the ice-flow direction estimates (radian) | ascii_thetaS | ArcGIS ASCII Raster format | ascii_thetaS.zip | 146167 |
| binary mask identifying where ice flow speed U exceeds 20 m/yr | ascii_Ugrt20 | ArcGIS ASCII Raster format | ascii_Ugrt20.zip | 3163 |
| browse image of the flow convergence map | image_convergenceC_450m3_with_key | TIFF | image_convergenceC_450m3_with_key.zip | 49970 |
| browse image of the map of flow orthonormal strain rate | image_strainrateSR_450m2_with_key | TIFF | image_strainrateSR_450m2_with_key.zip | 46264 |