The Hydrologic Outlets of the Greenland Ice Sheet data set contains GIS point shapefiles that include 891 observed and potential hydrologic outlets of the Greenland Ice Sheet, as identified by Lewis and Smith (2009), using satellite imagery. There are 460 observed hydrologic outlets that include proglacial streams and rivers emerging from the ice sheet (length scale >1 km), proglacial lakes touching the ice edge or clearly connected to it via streams or rivers (length scale >3 km), and sediment-rich plumes exiting tidewater glaciers into fjords. Also, there are 431 potential hydrologic outlets that include point locations with release of meltwater from fjords without obvious sediment discharge, as well as locations where the ice sheet directly connects to the ocean that cannot be proven to release meltwater.
Meltwater features along the entire edge of the ice sheet were mapped via photo interpretation of GoogleEarth and Landsat ETM+ 15 m panchromatic data. The exact acquisition dates of the imagery are not available; however, owing to the light and relatively snow-free conditions seen in the GoogleEarth and Landsat images, it is presumed that they were taken during the summer season. Neither Landsat or GoogleEarth images were available for a section of ice sheet within the northern Tunu region; therefore, that region was excluded from the study. This excluded area represents approximately 0.9 percent of the ice sheet perimeter. Data are available via FTP, and can be read in any GIS software. The following journal article provides documentation for this data set: Lewis, Sarah and Laurence Smith. 2009. Hydrologic Drainage of the Greenland Ice Sheet. Hydrological Processes doi: 10.1002/hyp.7343. This journal article can be accessed from the Documentation link at the top of this Web page.