NASA - National Aeronautics and Space Administration

Mission: North Central Gap 01 IS-2
Priority: High
 
This mission, along with the North Central Gap 02 and 03 missions, are primarily designed to fill a gap in altimetry and radar coverage of the north-central portion of the ice sheet. The flight was modified for 2015, where we removed the centerlines of Zachariæ Isstrøm and Storstrømmen Glaciers (covered in other flights), and added reflights of four 2010 grid lines on the upper Zachariæ/79N catchment, extended upstream centerlines of both glaciers, and a flowline passing through the TUNU core site. For 2019 we modify the east-west crossings to target low-latency IS-2 crossover latitudes, we replace the 2010 grid lines with low-latency ICESat-2 ground tracks, and we also fly parallel extensions of previous lines on the upper NEGIS. These extension lines are new.
 
Satellite imagery brought us again to our highest priority mission remaining in northeast Greenland. We proceeded along the southernmost low-latency ICESat-2 crossovers, both expecting and encountering low clouds that we passed above until about ~200 km in to the line. One of our ICESat-2 tracks in the grid above Zachariæ Isstrøm was low-latency (see below). Unfortunately, ATM T6 wide scan experienced a scanner motor failure and that motor will need to be replaced. About a third of the way through the survey, during the upstream grid, we decided to operate T6 in profiling mode after the mirror was adjusted so that the beam would be pointed at nadir. Given available time, we opted to extend our return line up from 79N to EGRIP at 16:22:40 UTC prior to rejoining the line across the ice sheet along a low-latency cross-over parallel in the hope of extending ice and snow layering records from the coast to that site. Clouds again returned as we crossed the central ice divide. ATM T7 narrow scan continues to function well. Headwall SWIR had to be restarted. MCoRDS and snow radar worked well. Due to low ceilings upon our return to Thule AB, we were again unable to perform a ramp pass.
 
ICESat-2 reference ground track (RGT) / targeted ICESat-2 beam / latency (positive/negative = ICESat-2 orbits before/after our flight)
154 / 1L / +8 days
276 / 3L / +5 hours
474 / 3L / -13 days
535 / 1L / -17 days
 
Attached images:

1. Map of today’s mission (John Sonntag / NASA)
2. Stack of 22 CAMBOT images of low clouds in northwestern Greenland, from which green reflections from ATM T-7 are visible (Jeremy Harbeck / NASA)
3. CAMBOT mosaic of EGRIP camp (Jeremy Harbeck / NASA)
4. Snow drifts associated that appear to be associated with upwind crevasses snake their way across a small, frozen supraglacial lake on Zachariæ Isstrøm (Joe MacGregor / NASA)
5. Alexey Chibisov inspecting ATM T6 below the cabin in-flight (Jeremy Harbeck / NASA)
6. Snow drifts on a frozen periglacial lake between Zachariæ Isstrøm and 79N glaciers (Jeremy Harbeck / NASA)