Revision date and time: 2011-10-1711:53:32
Antarctic and Greenland Drainage System Divides
Philosophy used to define the drainage system divides < Link to Mario’s documentation.
Antarctic Drainage System Divides
Drainage system divides for Antarctica were developed by Mario Giovinetto and digitized by Matthew Beckley. They are based on ERS elevations generated using the GSFC Version 4 retracker (Zwally and Brenner, 2001).[1] Vector maps (Figure 2) showing the downslope direction were generated, and drainage system divides were then drawn on these maps by Giovinetto, based primarily on the flow direction, guided by ???. The divides were digitized by Beckley using an Altek Datatab Pro Line Digitizer and (software, other info...), and the results were (confirmed how?). The ice boundary used to delineate the grounded portion of the drainage systems, and the outer ice boundary used to delineate the outer edges of the drainage systems are the MODIS/MOA boundaries available from NSIDC (Haran et al., 2005). The resulting drainage system divides are shown in Figure 3.
Table 1. Characteristics of the Antarctic DEM and vector maps
Projection / Polar-stereographic with standard latitude 71°S, orientation 0°, grid nodes at the centers of the cellsEllipsoid / 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.)
Source / ERS data ....
DEM Resolution / 5 km in each direction (nominal).
Vector map Resolution / 5 km in each direction (nominal)
Scale / cm/km on the maps Mario was working with??
Figure 1. Antarctic DEM used as basis for determining drainage system divides
Figure 2. Example of one of the vector maps used for determining locations of the drainage divides for Antarctica. Colors code the slope. Arrows are all the same length, spaced 5 km apart.
Figure 3. Antarctic drainage systems. Theaxes arelabelled with our 50-km polar- stereographic grid coordinates.The numbers on Antartica are the drainage system id’s.
Download the data <--- JAIRO: this should be a link to the data file.
Greenland Drainage System Divides
Drainage system divides for Greenland were developed by Mario Giovinetto and digitized by Matthew Beckley. They are based on the 1 km DEM of Greenland developed from ICESat/GLAS (Zwally et al., 2002) data by DiMarzio et al. (2007b). The DEM, shown in Figure 4, used data from the first seven GLAS campaigns (Table 2)[2]. Vector maps (Figure 5) showing the down slope direction were generated from this DEM (Table 3), and drainage system divides drawn on these maps by Giovinetto, based primarily on the flow direction, guided by ???. The divides were then digitized by Beckley using an Altek Datatab Pro Line Digitizer and (software, other info...). 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 ( that uses the chain-code algorithm; the boundary was then edited to remove anomalies. The resulting drainage system divides are shown in Figure 6.
Table 1. ICESat/GLAS campaigns used to
generate the Greenland DEM
Campaign / Start Date / End date1 / 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. Characteristics of the Greenland DEM and vector maps
Projection / Polar-stereographic with standard latitude 71°N, orientation 315°E, grid nodes at the centers of the cellsEllipsoid / 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.)
Resolution / 1 km in each direction (nominal)
Scale / cm/km on the maps Mario was working with??
Figure 6. Greenland drainage systems. The axes are labelled with our 50-km polar-stereographic grid coordinates. The numbers on Greenland are the drainage subsystem id's.
Download the data <--- JAIRO: this should be a link to the data file .
For further information contact Jack Saba
References
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. 2011b, Getting 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.
DiMarzio, J., A. Brenner, R. Schutz, C. A. Shuman, and H. J. Zwally, 2007a, GLAS/ICESat 1 km laser altimetry digital elevation model of Greenland, Boulder, Colorado USA: National Snow and Ice Data Center. Digital media,
DiMarzio, J., A. Brenner, R. Schutz, C. A. Shuman, and H. J. Zwally, 2007b, GLAS/ICESat 500 m laser altimetry digital elevation model of Antarctica, Boulder, Colorado USA: National Snow and Ice Data Center. Digital media,
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,
Zwally, H.Jay and Anita C. Brenner, 2001, “Ice Sheet Dynamics and Mass Balance,” 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., 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.
1
[1]We are currently working on updated drainage system divides based on early ICESat data. These should be ready in late 2011. The new drainage systems will incorporate the MODIS coastline (Haran et al., 2005) and the ASAID update to the MODIS grounding line (Bindschadler et al., 2010). In addition, an updated ICESat Antarctic DEM using all ICESat data is expected once the final release of the data is complete, probably later in 2011 or early in 2012, and the drainage systems will probably be updated again based on these.
[2]Updated maps are expected once the final release of the data is complete, probably later in 2011 or early in 2012.