Ice-stream-related patterns of ice flow in the interior of northeast Greenland

Ice flow in the interior of the NE quadrant of the Greenland ice sheet is focused on the large ice stream draining the north side of the summit dome. The rapid ice flow in the stream is apparent in the surface features in the stream and at the margins, in the broad scale topography that drives ice flow, and in satellite-derived ice motion information. The patterns of ice flow in the upper half of the stream are remarkable for their level of organization, simple geometry, and effects on local surface topography. The stream begins less than 100 kin from the ice divide as a current 15 km wide and then broadens symmetrically downstream by the addition of ice from the sides to a width of more than 60 km. Elevation data and visible-band imagery show that the stream has marginal troughs tens of meters deep in its upper reach which are coincident with regions of high shear strain rate. The topography of the margins and undulating surface of the stream is generated by the ice flow; the surface undulations in the stream are fixed in location and shape over the 5 year period from 1994 to 1999. The enhanced flow presents a challenge for researchers trying to understand the history of ice discharge from a significant area in the interior of the ice sheet.