{"dp_type": "Dataset", "free_text": "Bed Slope"}
[{"awards": "1246353 Anderson, John; 1745043 Simkins, Lauren; 1745055 Stearns, Leigh", "bounds_geometry": ["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"], "date_created": "Wed, 10 Nov 2021 00:00:00 GMT", "description": "The dataset here allows exploration of the causes and significance of Antarctic grounding-line sinuosity by coupling observations of contemporary Antarctic grounding lines and paleo-grounding lines expressed as ice-marginal landforms on the Ross Sea continental shelf. Modern grounding lines are derived from the MEaSUREs Version 2 Differential Satellite Radar Interferometry dataset with spatial resolutions of 25-120 m spanning February 1992 to December 2014 (Rignot et al., 2016; Mouginot et al., 2017). The boundaries of individual grounding lines representative of individual glacial catchments (n=664) were delineated by the inflection points of the shear strain rate, \u03b5xy (c.f Van der Veen et al., 2011). Sinuosity was calculated as the ratio of the true length, orthogonal to ice-flow direction, of the grounding lines and the straight line length between end-points and in units of km/km. Raster data were extracted at 1-km points along each grounding line; the mean was calculated for each grounding line and merged in a table with sinuosity data. A dataset of 6,275 paleo-grounding lines expressed as ice-marginal landforms on the deglaciated western Ross Sea continental shelf are used in this study, originally published by Simkins et al., 2018. The ice-marginal landforms were mapped from multibeam echo sounder data that was collected onboard the RVIB Nathaniel B. Palmer (NBP) 15-02 cruise using a Kongsberg EM122 operating in dual swath mode at 12 kHz frequency with 30-60% swath overlap (Cruise DOI: 10.7284/901477). The resulting bathymetry data was gridded at 20-40 m with decimeter vertical elevation resolution depending on water depth and sea-state. Sinuosity is calculated as a ratio of true (mapped) landform length, measured in the across paleo-ice flow direction at the crest of the landform, to the straight line distance between the mapped landform endpoints and in units of km/km. \r\n\r\nTo compare modern and paleo-grounding lines, we use a consistent length scale by segmenting the grounding lines into 2-km sections for the two datasets (modern, n=12,966; paleo, n=5,832), even though this eliminates grounding lines that are less than 2-km long and thus results in 1 modern and 3,873 paleo-grounding lines removed. The full-length and 2-km segmented groundings lines are provided as shapefiles \"InSAR_groundinglines_full\" and \"InSAR_groundinglines_2km\", the paleo-grounding lines are provided as shapefiles \"RossSea_icemarginal_full\" and \"RossSea_icemarginal_2km\", and points marking modern grounding lines retreat from repeat InSAR surveys are provided as shapefile \"InSAR_retreat_points\", all stored together in a geodatabase named \"Antarctic_groundinglines.gbd\". Additional grounding line metrics, including length, sinuosity, bed roughness, and bed slope for modern and paleo-grounding lines, and height-above-buoyancy gradient, ice-flow velocity, presence of pinning points and ice shelves are provided for modern grounding lines. \r\n\r\nThe published dataset was compiled and analyzed in the article \"Controls on circum-Antarctic grounding-line sinuosity \" by Simkins, L.M., Stearns, L.A., and Riverman, K.L, which will be submitted to a peer-review journal in November 2021.\r\n\r\nReferences\r\nMouginot, J., B. Scheuchl, and E. Rignot. 2017. MEaSUREs Antarctic Boundaries for IPY 2007-2009 from Satellite Radar, Version 2. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. \r\n\r\nRignot, E., J. Mouginot, and B. Scheuchl. 2016. MEaSUREs Antarctic Grounding Line from Differential Satellite Radar Interferometry, Version 2. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. \r\n\r\nSimkins, L. M., Greenwood, S. L., \u0026 Anderson, J. B. (2018). Diagnosing ice sheet grounding line stability from landform morphology. The Cryosphere, 12(8), 2707-2726.\r\n\r\nVan der Veen, C. J., J. C. Plummer, \u0026 L. A. Stearns. (2011). Controls on the recent speed up of Jakobshavn Isbr\u00e6, West Greenland. Journal of Glaciology, 57(204), 770-782", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Antarctica; Bed Roughness; Bed Slope; Elevation; Glaciers/ice Sheet; Glaciers/Ice Sheet; Pinning Points", "locations": "Antarctica; Antarctica", "north": -60.0, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Earth Sciences; Antarctic Earth Sciences", "persons": "Simkins, Lauren; Stearns, Leigh; Riverman, Kiya", "project_titles": "Collaborative Research: Topographic controls on Antarctic Ice Sheet grounding line retreat - integrating models and observations; Evidence for Paleo Ice Stream Collapse in the Western Ross Sea since the Last Glacial Maximum.", "projects": [{"proj_uid": "p0010269", "repository": "USAP-DC", "title": "Collaborative Research: Topographic controls on Antarctic Ice Sheet grounding line retreat - integrating models and observations"}, {"proj_uid": "p0000395", "repository": "USAP-DC", "title": "Evidence for Paleo Ice Stream Collapse in the Western Ross Sea since the Last Glacial Maximum."}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Circum-Antarctic grounding-line sinuosity", "uid": "601484", "west": -180.0}]
X
X
Help on the Results MapX
This window can be dragged by its header, and can be resized from the bottom right corner.
Clicking the Layers button - the blue square in the top left of the Results Map - will display a list of map layers you can add or remove
from the currently displayed map view.
The Results Map and the Results Table
- The Results Map displays the centroids of the geographic bounds of all the results returned by the search.
- Results that are displayed in the current map view will be highlighted in blue and brought to the top of the Results Table.
- As the map is panned or zoomed, the highlighted rows in the table will update.
- If you click on a centroid on the map, it will turn yellow and display a popup with details for that project/dataset - including a link to the landing page. The bounds for the project(s)/dataset(s) selected will be displayed in red. The selected result(s) will be highlighted in red and brought to the top of the table.
- The default table sorting order is: Selected, Visible, Date (descending), but this can be changed by clicking on column headers in the table.
- Selecting Show on Map for an individual row will both display the geographic bounds for that result on a mini map, and also display the bounds and highlight the centroid on the Results Map.
- Clicking the 'Show boundaries' checkbox at the top of the Results Map will display all the bounds for the filtered results.
Defining a search area on the Results Map
- If you click on the Rectangle or Polygon icons in the top right of the Results Map, you can define a search area which will be added to any other search criteria already selected.
- After you have drawn a polygon, you can edit it using the Edit Geometry dropdown in the search form at the top.
- Clicking Clear in the map will clear any drawn polygon.
- Clicking Search in the map, or Search on the form will have the same effect.
- The returned results will be any projects/datasets with bounds that intersect the polygon.
- Use the Exclude project/datasets checkbox to exclude any projects/datasets that cover the whole Antarctic region.
Viewing map layers on the Results Map
To sort the table of search results, click the header of the column you wish to search by. To sort by multiple columns, hold down the shift key whilst selecting the sort columns in order.
| Dataset Title/Abstract/Map | NSF Award(s) | Date Created | PIs / Scientists | Project Links | Abstract | Bounds Geometry | Geometry | Selected | Visible |
|---|---|---|---|---|---|---|---|---|---|
|
Circum-Antarctic grounding-line sinuosity
|
1246353 1745043 1745055 |
2021-11-10 | Simkins, Lauren; Stearns, Leigh; Riverman, Kiya |
Collaborative Research: Topographic controls on Antarctic Ice Sheet grounding line retreat - integrating models and observations Evidence for Paleo Ice Stream Collapse in the Western Ross Sea since the Last Glacial Maximum. |
The dataset here allows exploration of the causes and significance of Antarctic grounding-line sinuosity by coupling observations of contemporary Antarctic grounding lines and paleo-grounding lines expressed as ice-marginal landforms on the Ross Sea continental shelf. Modern grounding lines are derived from the MEaSUREs Version 2 Differential Satellite Radar Interferometry dataset with spatial resolutions of 25-120 m spanning February 1992 to December 2014 (Rignot et al., 2016; Mouginot et al., 2017). The boundaries of individual grounding lines representative of individual glacial catchments (n=664) were delineated by the inflection points of the shear strain rate, εxy (c.f Van der Veen et al., 2011). Sinuosity was calculated as the ratio of the true length, orthogonal to ice-flow direction, of the grounding lines and the straight line length between end-points and in units of km/km. Raster data were extracted at 1-km points along each grounding line; the mean was calculated for each grounding line and merged in a table with sinuosity data. A dataset of 6,275 paleo-grounding lines expressed as ice-marginal landforms on the deglaciated western Ross Sea continental shelf are used in this study, originally published by Simkins et al., 2018. The ice-marginal landforms were mapped from multibeam echo sounder data that was collected onboard the RVIB Nathaniel B. Palmer (NBP) 15-02 cruise using a Kongsberg EM122 operating in dual swath mode at 12 kHz frequency with 30-60% swath overlap (Cruise DOI: 10.7284/901477). The resulting bathymetry data was gridded at 20-40 m with decimeter vertical elevation resolution depending on water depth and sea-state. Sinuosity is calculated as a ratio of true (mapped) landform length, measured in the across paleo-ice flow direction at the crest of the landform, to the straight line distance between the mapped landform endpoints and in units of km/km. To compare modern and paleo-grounding lines, we use a consistent length scale by segmenting the grounding lines into 2-km sections for the two datasets (modern, n=12,966; paleo, n=5,832), even though this eliminates grounding lines that are less than 2-km long and thus results in 1 modern and 3,873 paleo-grounding lines removed. The full-length and 2-km segmented groundings lines are provided as shapefiles "InSAR_groundinglines_full" and "InSAR_groundinglines_2km", the paleo-grounding lines are provided as shapefiles "RossSea_icemarginal_full" and "RossSea_icemarginal_2km", and points marking modern grounding lines retreat from repeat InSAR surveys are provided as shapefile "InSAR_retreat_points", all stored together in a geodatabase named "Antarctic_groundinglines.gbd". Additional grounding line metrics, including length, sinuosity, bed roughness, and bed slope for modern and paleo-grounding lines, and height-above-buoyancy gradient, ice-flow velocity, presence of pinning points and ice shelves are provided for modern grounding lines. The published dataset was compiled and analyzed in the article "Controls on circum-Antarctic grounding-line sinuosity " by Simkins, L.M., Stearns, L.A., and Riverman, K.L, which will be submitted to a peer-review journal in November 2021. References Mouginot, J., B. Scheuchl, and E. Rignot. 2017. MEaSUREs Antarctic Boundaries for IPY 2007-2009 from Satellite Radar, Version 2. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. Rignot, E., J. Mouginot, and B. Scheuchl. 2016. MEaSUREs Antarctic Grounding Line from Differential Satellite Radar Interferometry, Version 2. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. Simkins, L. M., Greenwood, S. L., & Anderson, J. B. (2018). Diagnosing ice sheet grounding line stability from landform morphology. The Cryosphere, 12(8), 2707-2726. Van der Veen, C. J., J. C. Plummer, & L. A. Stearns. (2011). Controls on the recent speed up of Jakobshavn Isbræ, West Greenland. Journal of Glaciology, 57(204), 770-782 | ["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"] | ["POINT(0 -89.999)"] | false | false |
