NASA - National Aeronautics and Space Administration

Mission: North Bed Gap 01
Priority: High
 
This new mission for 2019 addresses gaps in bed measurements identified by Mathieu Morlighem on the northern and northeastern flank of the ice sheet. We also fly two short flowlines in the vicinity of Steensby and Ryder Glaciers at the request of MacGregor et al, with the purpose of recovering thickness, and possibly layering, in an area with the best surface exposure of pre-Holocene ice in all of Greenland. This data would enable future modeling there to support a possible “horizontal ice core” effort. Finally, we fly a line across the margin of the Hiawatha ice lobe and across a river channel in its proglacial area, at the request of Larry Smith.
 
A mixed forecast today across the region led us to head northeast today and cover some new ground. To our mild surprise, this mission turned out to be  a near-perfect match for the conditions we encountered. Clouds west of the divide dissipated as we descended to begin the survey of bed gaps in north and northeast Greenland. The bed gap lines proceeded uneventfully in MCoRDS swath mode and then we proceeded to fly two flowlines, terminating in Warming Land, in MCoRDS nadir profiling mode to offer the best opportunity to detecting internal layering. Due to thin snow cover there, we were also able to observe the dusty layering associated with Last Glacial Period ice at the ice margin. We then transited over Steensby and Petermann Glaciers to perform a short survey perpendicular to the ice margin in Inglefield Land west of Hiawatha Glacier in support of Larry Smith’s hydrology project. During this transit, clouds returned and we climbed above them near Petermann Glacier. They cleared in time for us to spot the Keybird wreck again, but returned over Humboldt Glacier and dissipated again just in time for the Inglefield Land transect. Headwall continues to have minor freezing issues and the same Applanix IMU malfunctioned later on than yesterday, but ATM has a good lead on a resolution. Otherwise, all instruments performed well and ATM reports 99% laser altimetry collection. Due to low ceilings at Thule, we did not perform a ramp pass.
 
Attached images:

1. Map of today’s mission (John Sonntag / NASA)
2. The bed gaps filled by today’s mission (white line) through highs in bed elevation uncertainty, where red saturates at 500 meters uncertainty (Joe MacGregor / NASA)
3. Snow-filled crevasse field upstream of Ryder Glacier (Jeremy Harbeck / NASA)
4. Margin of the Greenland Ice Sheet abutting Warming Land (Jeremy Harbeck / NASA)
5. Contrast-stretched view of the margin of the Greenland Ice Sheet abutting Warming Land, just east of Steensby Glacier. Brown layers signify dusty ice from colder intervals (stadials) during the Last Glacial Period, and this outcrop represents a location with potentially some of the oldest ice exposed at the surface in Greenland. While the colors in this image are adjusted, these layers were visible to the naked eye. (Joe MacGregor / NASA)