Antarctic and Greenland Drainage Systems

 

Antarctic Drainage System Boundaries and Masks

Figure 1 shows the Antarctic drainage divides developed by the Goddard Ice Altimetry Group from ICESat data. Our definitions of the West Antarctic ice sheet (systems 18-23 and 1), the East Antarctic ice sheet (systems 2-17), and the Antarctic Peninsula (systems 24-27) allocate the drainage systems according to ice provenance with separation of East and West Antarctica approximately along the Transantarctic Mountains. The parts of the Ronne and Filchner ice shelves in systems 2 and 3, and the western part of the Ross Ice Shelf in system 17, are implicitly allocated to East Antarctica. The drainage systems include all basins and sub-basins in each, and due to sporadic ice shelf advance and break-back, are drawn to prominent points on the coastline (e.g., between systems 8 and 9), not to specific junction points of coastline, ice front, or grounding line; users should make adjustments to the area and other statistics that would be affected if different junction points are selected.

Figure 1. Antarctic drainage systems. The numbers on Antarctica are the drainage system IDs. The portions of the drainage systems within the grounding line are filled with solid color. The portions between the grounding line and the coastline are hatched.

 

From the Antarctic drainage system boundaries, we generated two 1-km polar-stereographic grids: a grid giving the drainage system for each cell, and a grid giving the surface type (continental, floating, or island/ice rise). By continental, we mean the region inside the MODIS grounding line; within this region we have no way to distinguish between ice-covered surfaces and other surfaces. Islands and ice rises are defined by the MODIS island polygons; the surfaces may or may not be ice-covered. Floating ice is the rest of the area between the MODIS grounding line and our modified MODIS coastline; it includes both glacier tongues and ice shelves. The final grids give the surface specification (continent, ice shelf, or island/ice rise), and the drainage system (1-27) for each 1 km grid cell. Figure 2 is a map of the surface types (the 1 km point-by-point drainage system map is indistinguishable from Figure 1).

 

Figure 2. Surface type map. Cyan: water/sea ice, Blue: continent. Green: island/ice rise. Orange: ice shelf

For Antarctica, we also have images of the drainage divides overlaid on Mosaic of Antarctica maps (Haran et al., 2005) and on an ice velocity map (Rignot et al., 2011) available for download.

The following links access files available for download:

  • Full Antarctic drainage divides (including floating ice) [download data]
  • Grounded portions of the Antarctic drainage divides [download data]
  • Antarctic surface specification and drainage system grids [download data]
  • Images of the Antarctic drainage divides on MOA maps [download data]
  • Images of the Antarctic drainage divides on Rignot velocity maps [download data]

 

Greenland Drainage System Boundaries

Figure 3 shows the Greenland drainage divides developed by the Goddard Ice Altimetry Group from ICESat data. We do not provide a Greenland surface type mask because it is available at source (Ekholm, 1996).

 

Figure 3. Greenland drainage divides. The axes are labeled with our 50-km polar-stereographic grid coordinates. The numbers on Greenland are the drainage subsystem IDs.

File available for download:

Citation

Use the following reference for this page or the data accessed from this page:

Zwally, H. Jay, Mario B. Giovinetto, Matthew A. Beckley, and Jack L. Saba, 2012, Antarctic and Greenland Drainage Systems, GSFC Cryospheric Sciences Laboratory, at
http://icesat4.gsfc.nasa.gov/cryo_data/ant_grn_drainage_systems.php.

 

Drainage Systems and Divides

Ice sheet drainage systems were delineated to identify regions broadly homogeneous regarding surface slope orientation relative to atmospheric advection, and additionally in the case of Antarctica, denoting the ice sheet areas feeding large ice shelves. Systems and sub-systems include one or more primary basins, each identifiable with a particular outlet glacier or ice stream that drains the interior of an ice sheet, plus secondary basins that complete the periphery of an ice sheet and are normally ignored in net mass budget estimates based on input-minus-output methods. The drainage system schemes for Antarctica and Greenland cover the entire area within the coterminous coastline.

 

Antarctic Drainage System Divides

Drainage system divides developed by the Ice Altimetry Group at Goddard Space Flight Center for Antarctica in 2001 were based on ERS altimetry denoting ice provenance from either East Antarctica or West Antarctica (Zwally, et al., 2002). See Figure 4 for a comparison of the ICESat-based drainage divides to the ERS-based drainage divides. The divides shown in Figure 1 are based on the 500 m DEM of Antarctica (Figure 5) developed from ICESat/GLAS first seven GLAS campaigns (Table 1) (Zwally et al., 2002; DiMarzio et al., 2007a), supplemented by topographic information in the area south of 86° S from several sources (e.g., Liu et al., 2001; Jezek et al., 2002).

Figure 4. Old vs new drainage divides. The colored blocks show the new drainage systems. The lines show the old (ERS-based) drainage systems.

 

Figure 5. Antarctic DEM

Vector maps (Figure 6) showing the downslope maximum-gradient direction were generated from the DEM, and drainage system divides were then drawn on these maps, primary divides along major ridges, and secondary divides starting at points of interest on the coastline (e.g., between systems 6 and 7) or grounding zone (e.g., between systems 18 and 19), drawn upslope until meeting a primary divide or another secondary divide. The divides were continued on the ice shelves based on a combination of surface elevation, shear crevasses, rumples and dolines orientation, as well as ice-front lobe splits. A number of other sources, such as the Landsat Image Mosaic of Antarctica (Bindschadler et al., 2008, 2011a,b) and the MODIS Mosaic of Antarctica (Haran et al., 2005), were used to help refine the drainage divides on some of the ice shelves.

 

Figure 6. This vector map is representative of the plots that were used to determine the drainage divides. The arrows point in the downslope direction. Color codes the slope. The orange lines are the drainage divides from the earlier (ERS-based) GSFC drainage divides. The black lines are the new drainage divides. The gray lines at a slight angle to the axes are lines of latitude and longitude. The gray lines parallel to the axes are the edges of our 50 km grid cells.

 

Drainage divides were digitized using ArcGIS v 9.3. For the majority of the divides, the digitization was done from paper maps of the slope vectors (Figure 6) via an Altek Datatab Pro Line puck digitizer. However, in regions where the slope vectors did not yield useful information, imagery from the RADARSAT Antarctic Mapping Project (RAMP; Jezek et al., 2002), Modis Mosaic of Antarctica (MOA; Haran et al., 2005), and the Landsat Image Mosaic of Antarctica (LIMA; Bindschadler et al., 2008, 2011a, b), was used as a guide. These images were viewed in ArcGIS with the divides and other relevant layers such as contours, rock outcrops, etc. Divides were then edited on screen using all available data as a guide. This method was used in parts of the Antarctic Peninsula, and the Filchner/Ronne and Ross ice shelves.

Divides were drawn to the MOA coastline (Haran et al., 2005). This coastline was edited to remove minor errors such as dangling nodes, improper loops, etc. This was done so that the divides could be converted to polygons, which requires the points to be ordered consecutively. Once this was done, polygons extended to the coast were created via a third party GIS application called Xtools. The grounded versions of the polygons were generated by masking the coastline polygons with the MOA grounding line (Haran et al., 2005), using the clipping function in ArcGIS. The resulting drainage system divides are shown in Figure 1.

Table 3 gives some statistics related to the divide boundaries.

 

Antarctic Issues

We modified the MODIS coastline developed by Haran et al., 2005 as described above. Thus the coastline used here is not identical to that of Haran et al., 2005.

The MODIS grounding line is not the latest or the best available grounding line for Antarctica. It would be better to use the ASAID grounding line (Bindschadler et al., 2008, 2011a, b), but there are too many inconsistencies between that line and the MODIS coastline.

Some islands are not include in the MODIS island polygons. In particular, we note that Sherman Island in the Abbot Ice Shelf is not present.

The ICESat DEM used to determine the locations of the drainage divides was made with only the first 2 years of ICESat data, and an early release of the data was used.

The drainage system outlines used here are defined in WGS84 coordinates. This was ignored in this work, and the coordinates were treated as if they were Topex coordinates. The maximum difference between Topex and WGS84 latitude occurs at a latitude of 45°, and is approximately 1.37 cm, so treating the WGS84 coordinates as if they were Topex coordinates should not have a detectable effect on the results.

 

Greenland Drainage System Divides

Greenland drainage system divides developed in 2001 were based on ERS altimetry (Zwally and Giovinetto, 2001; Zwally et al., 2005) and drawn on surface vector maps showing the down-slope maximum gradient direction at 5-km resolution derived from the ERS-1 database  (Zwally and Brenner, 2001) and slightly modified based on ERS-1 and -2 databases (Zwally et al., 2005). The drainage divides presented here are based on ICESat altimetry (Zwally et al., 2011) drawn on surface vector maps derived from the 1-km DEM of Greenland developed from ICESat/GLAS data (Zwally et al., 2002; DiMarzio et al., 2007b). See Figure 7 for a comparison of the new drainage systems to the drainage divides from the ERS-based drainage systems.

 

Figure 7. Old vs new drainage divides. The colored blocks show the new drainage systems. The lines show the old (ERS-based) drainage systems.

 

Figure 8. Greenland DEM

 

The DEM, shown in Figure 8, used data from the first seven GLAS campaigns (Table 1). Vector maps (Figure 6) showing the downslope maximum-gradient direction were generated from this DEM (Table 2). Drainage system divides were drawn on these maps, primary divides along major ridges, and secondary divides starting at points of interest either on the coastline or along the ice terminus, drawn upslope until meeting a primary divide or another secondary divide. The drainage systems and sub-systems include all basins and sub-basins in each; users should make adjustments to the size of the area and other statistics that would be affected if different starting points are selected to meet the need of particular projects.

Drainage divides were digitized using ArcGIS v 9.3. The digitization was done from paper maps of the slope vectors (Figure 6) via an Altek Datatab Pro Line puck digitizer. The ice sheet boundary included in the drainage system divides was defined based on Ekholm's (1996) surface type map with an IDL™ routine (find_boundary.pro) developed by David Fanning (http://www.idlcoyote.com) that uses the chain-code algorithm; the boundary was then edited to remove anomalies. The polygons extended to the line were generated via a third party GIS application called Xtools. The resulting drainage system divides are shown in Figure 3. Table 4 gives some statistics related to the divide boundaries.

Greenland Issues

The ICESat DEM used to determine the locations of the drainage divides was made with only the first 2 years of ICESat data, and an early release of the data was used.

When more and/or different data are processed, it might be possible to draw a divide in the western and northern area of sub-system 2.1 to isolate a well known ice stream basin, and a divide separating a smaller eastern region from the rest in system 5.

The drainage system outlines used here are defined in WGS84 coordinates. This was ignored in this work, and the coordinates were treated as if they were TOPEX coordinates. The maximum difference between TOPEX and WGS84 latitude occurs at a latitude of 45°, and is approximately 1.37 cm, so treating the WGS84 coordinates as if they were TOPEX coordinates should not have a detectable effect on the results.


 

Table 1. ICESat/GLAS campaigns used to generate the Greenland DEM

Campaign

Start Date

End Date

1

2003 Feb 2

2003 Mar 29

2a

2003 Sep 25

2003 Nov 19

2b

2004 Feb 17

2004 Mar 21

2c

2004 May 18

2004 Jun 21

3a

2004 Oct 3

2004 Nov 8

3b

2005 Feb 17

2005 Mar 24

3c

2005 May 20

2005 Jun 23

 

Table 2. Projection and vector map information

Projection Polar-stereographic, grid nodes at the centers of the cells
Ellipsoid Topex/Poseidon (REq=6378.136300 km, Eccentricity=0.08181922146) (The elevation grids available at NSIDC have elevations relative to the WGS-84 ellipsoid and EGM96 geoid although the node locations are still based on the Topex/Poseidon polar-stereographic grid. We used our original version, with elevations based on the T/P ellipsoid.)
 

Greenland

Antarctica

Standard Latitude 70° N 70° S
Orientation Line from North Pole along 315°E runs vertically down in the grid Line from the South Pole along 0° runs vertically upward in the grid
DEM resolution 1 km in each direction (nominal) 500 m in each direction (nominal)
Vector map resolution 1 km in each direction (nominal) 1 km in each direction (nominal)
Vector map scale 16.9 cm = 50 km 14.5 cm = 50 km

 

Table 3. Antarctic drainage divide boundary statistics

 

Full drainage system

Grounded part

Drainage System Number of points in boundary Average spacing (m) Total length (km) Area (km2) Number of points in boundary Average spacing (m) Total length (km) Area (km2) Length of grounding line (km)
1 35575 119 4257 783290 81595 92 7519 501448 4521
2 28269 195 5538 933754 43096 129 5600 830000 1343
3 51028 114 5848 1615608 72275 90 6566 1565727 1303
4 36498 106 3893 329331 42405 101 4293 247879 2548
5 23554 123 2908 238176 26716 112 3016 190978 1334
6 53860 108 5853 693328 57276 101 5812 610797 3199
7 54620 110 6024 501239 66599 98 6554 493593 3604
8 36631 80 2958 159742 36631 80 2958 159742 1545
9 15901 137 2185 166335 23734 115 2731 146029 1401
10 43149 128 5533 943263 42782 105 4521 919041 154
11 22862 126 2901 273145 28905 109 3178 257286 957
12 43804 128 5649 773999 61527 87 5369 722224 3065
13 45889 133 6106 1126542 66193 106 7074 1109771 3302
14 42391 135 5734 726359 52075 123 6443 710953 3688
15 24420 137 3357 133755 43282 100 4330 125183 3533
16 28133 152 4282 271666 31160 136 4267 265243 16278
17 51845 157 8155 2100069 71753 146 1052 1852382 3852
18 23722 174 4145 411835 29904 132 3962 269776 1350
19 22882 159 3654 481061 44109 104 4600 382018 1826
20 42212 114 4821 255065 57274 96 5517 201853 3937
21 22394 127 2847 228632 35270 91 3223 217404 1237
22 26262 112 2960 220317 33304 99 3324 214497 769
23 26205 118 3106 129689 39470 87 3450 91266 2423
24 35486 133 4721 213415 21965 132 2908 160848 1445
25 31728 156 4970 35398 42919 119 5110 34621 3549
26 20081 171 3448 102575 46024 112 5191 43085 3824
27 11921 146 1745 69444 40758 75 3080 54146 2300

 

Table 4. Greenland drainage divide boundary statistics

Drainage Subsystem Number of points in boundary Average spacing (m) Total length (km) Area (km2) Length of grounding line (km)
1.1 17114 134 2296 131115 776
1.2 10757 210 2264 63773 1137
1.3 9397 219 2062 46152 1128
1.4 8313 133 1105 17536 357
2.1 27970 111 3104 274220 1037
2.2 19343 87 1684 51196 437
3.1 18771 237 4441 148090 3183
3.2 6553 455 2985 35619 2661
3.3 16102 115 1854 73232 876
4.1 16540 122 2019 64669 1016
4.2 11326 108 1226 46802 451
4.3 8426 196 1651 33326 1077
5.0 7246 320 2322 49738 1832
6.1 7575 184 1396 49909 743
6.2 18012 142 2552 136902 1209
7.1 19210 76 1452 95213 54
7.2 18349 112 2059 130027 786
8.1 23381 120 2803 241556 1126
8.2 8580 292 2504 33497 1907

 


References

Bindschadler, R., Patricia Vornberger, Andrew Fleming, Adrian Fox, Jerry Mullins, Douglas Binnie, Sara Jean Paulsen, Brian Granneman, and David Gorodetzky, 2008, The Landsat Image Mosaic of Antarctica, Remote Sensing of Environment 112 (2008) 42144226. Accessed at http://lima.usgs.gov/access.php

Bindschadler, R., H. Choi, and ASAID Collaborators, 2011a, High-resolution Image-derived Grounding and Hydrostatic Lines for the Antarctic Ice Sheet. Boulder, Colorado, USA: National Snow and Ice Data Center. Digital media, accessed 2011 Sep 27.

Bindschadler, R., H. Choi, A. Wichlacz, R. Bingham, J. Bohlander, K. Brunt, H. Corr, R. Drews, H. Fricker, M. Hall, R. Hindmarsh, J. Kohler, L. Padman, W. Rack, G. Rotschky, S. Urbini, P. Vornberger, and N. Young. 2011bGetting around Antarctica: New High-Resolution Mappings of the Grounded and Freely-Floating Boundaries of the Antarctic Ice Sheet Created for the International Polar Year. The Cryosphere Discussions, 5, 183-227. doi:10.5194/tcd-5-183-2011, accessed 2011 Oct 20.

DiMarzio, J., A. Brenner, R. Schutz, C. A. Shuman, and H. J. Zwally, 2007aGLAS/ICESat 500 m laser altimetry digital elevation model of Antarctica, Boulder, Colorado USA: National Snow and Ice Data Center. Digital media.

DiMarzio, J., A. Brenner, R. Schutz, C. A. Shuman, and H. J. Zwally, 2007bGLAS/ICESat 1 km laser altimetry digital elevation model of Greenland, Boulder, Colorado USA: National Snow and Ice Data Center. Digital media.

Ekholm, Simon, 1996, “A full coverage, high-resolution, topographic model of Greenland computed from a variety of digital elevation data, ”Journal of Geophysical Research, 101 (B10), 21961-21972, 1996 Oct 10, doi:10.1029/96JB01912.

Haran, T., J. Bohlander, T. Scambos, T. Painter, and M. Fahnestock compilers, 2005, updated 2006. MODIS Mosaic of Antarctica (MOA) Image Map, Boulder, Colorado USA: National Snow and Ice Data Center. Digital media, accessed 2011 Sept 27

Jezek, K., and RAMP Product Team, 2002. RAMP AMM-1 SAR Image Mosaic of Antarctica. Fairbanks, AK: Alaska SAR Facility, in association with the National Snow and Ice Data Center, Boulder, CO. Digital media.

Liu, H., K. Jezek, B. Li, and Z. Zhao. 2001. Radarsat Antarctic Mapping Project digital elevation model version 2. Boulder, CO: National Snow and Ice Data Center. Digital media.

Rignot, E., J. Mouginot, and B. Scheuchl. 2011. MEaSUREs InSAR-Based Antarctica Velocity Map [list dates of data used]. Boulder, Colorado USA: NASA EOSDIS DAAC at NSIDC, accessed 2012 Feb.

Zwally, H. J. and Anita C. Brenner, 2001, “Ice Sheet Dynamics and Mass Balance,” in L.L. Fu and A. Cazenave (eds.), Satellite Altimetry and Earth Sciences, Academic Press, pp 351-369, doi:10.1016/S0074-6142(01)80154-6.

Zwally, H. J. and Mario B. Giovinetto, 2001, Balance mass flux and ice velocity across the equilibrium line in drainage systems of Greenland, Journal of Geophysical Research,, Vol. 106, No. D24, 33,717-33,728, 2001. doi:10.1029/2001JD900120.

Zwally, H. J., M. A. Beckley, A. C. Brenner, and M. B. Giovinetto, 2002, Motion of major ice-shelf fronts in Antarctica from slant- range analysis of radar altimeter data, 1978-98, Annals of Glaciology 34 (1), 255-262.

Zwally, H. J. , B. Schutz, W. Abdalati, J. Abshire, C. Bentley, A. Brenner, J. Bufton, J. Dezio, D. Hancock, D. Harding, T. Herring, B. Minster, K. Quinn, S. Palm, J. Spinhirne, and R. Thomas, 2002, ICESat’s laser measurements of polar ice, atmosphere, ocean, and land, Journal of Geodynamics, 34(3-4), 405-445, doi:10.1016/S0264-3707(02)00042-X.

Zwally, H. J., M. B. Giovinetto, J. Li, H. G. Cornejo, M. A. Beckley, A. C. Brenner, J. L. Saba, and D. Yi., 2005, “Mass Changes of the Greenland and Antarctic Ice Sheets and shelves and Contributions to Sea-Level Rise: 1992-2002,” Journal of Glaciology, Vol. 51, No. 175, pp 509-527, 2005.

Zwally, H. J., Jun LI, Anita C. Brenner, Matthew Beckley, Helen G. Cornejo, John DiMarzio, Mario B. Giovinetto, Thomas A. Neumann, John Robbins, Jack L. Saba, Donghui Yi, Weili Wang, 2011, “Greenland ice sheet mass balance: distribution of increased mass loss with climate warming; 200307 versus 19922002,” Journal of Glaciology, Vol. 57, No. 201, pp 88-102, 2011.