Mass balance of the northeast sector of the Greenland ice sheet: a remote-sensing perspective

Abstract

ABSTRACT. Synthetic-aperture radar interferometry data and airborne ice-sounding radar (ISR) data are employed to obtain modern estimates of the inland ice production from Nioghalvfjerdsbr× (NB) and Zachariae IsstrÖm (ZI), the two largest glaciers draining the northeast sector of the Greenland ice sheet. Ice fluxes are measured at the grounding line (14.2 AE1km 3 ice a^1 for NB and 10.8 AE1km 3 ice a^1 for ZI) with an ice thickness deduced from ice-shelf hydrostatic equilibrium, and along an ISR profile collected upstream of the grounding line (14.3 AE 0.7 km 3 ice a^1 for NB and 11.6 AE 0.6 km 3 ice a^1 for ZI). Balance fluxes calculated from a map of snow accumulation and model predictions of surface melt are 11.9 AE 2 km 3 ice a^1 for NB and 10.0 AE 2 km 3 ice a^1 for ZI at the grounding line, and 12.2 and 10.3 km 3 ice a^1, respectively, at the ISR line. The two glaciers therefore exhibit a negative mass balance equivalent to 14% of their balance flux, with a AE12% uncertainty. Independently, we detect a retreat of the grounding line of NB between 1992 and 1996 which is larger at the glacier center (920 AE 250 m) than on the sides (240 AE 50 m). The corresponding ice-thinning rates (2 AE1m a^1at the glacier center and 0.6 AE 0.3 m a^1on the sides) are too large to be accommodated by temporal changes in ablation or accumulation, and must be due to dynamic thinning.

Improved estimation of the mass balance of glaciers draining into the Amundsen Sea sector of West Antarctica from the CECS/NASA 2002 campaign

“…On the ice shelf, InSAR velocities were corrected from ocean tides. The correction assumes a purely elastic tidal deformation of ice shelves (Rignot and others, 2000) and employs tidal predictions from the FES99 tidal model (Lefevre and others, 2002).…”

Improved Delineation of Individual Outlet Glacier Drainage Basins From Tandem-X Elevations And Sentinel-1 Velocities

“…For the delineation of individual glacier drainage basins on the ice sheets a combination of ice flow direction from ice velocity measurements and ice flow along the steepest surface slope in the DEM has been shown. [22] and [6] already pro- Table 1. Drainage basin statistics of the largest 3 drainage basins in Northeast Greenland.…”

Glaciological advances made with interferometric synthetic aperture radar

“…Over roughly the same period (200205), the two largest glaciers on Greenland’s east coast, Kangerdlugssuaq Gletscher and Helheimgletscher, also sped up dramatically as their respective termini retreated (Howat and others, 2005;Luckman and others, 2006), with earlier observations from the 1990s on Kangerdlugssuaq indicating some precursor thinning and variation in speed (Thomas and others, 2000). During this period, many of the glaciers in the southeast and northwest also sped up substantially (Rignot and others, 2004b, 2008a;Rignot and Kanagaratnam, 2006; Howat and others, 2008;Joughin and others, 2010a).…”

“…Velocity fields derived from InSAR have also been used in many forward-modelling studies. For instance, on PIG, several authors have used InSAR data to tune models to examine the response to changes in geometry and grounding-line position (Schmeltz and others, 2002a;Payne and others, 2004; Thomas and others, 2004; Joughin and others, 2010b). Interferometrically determined velocities have also been used to determine horizontal advection in studies that modelled englacial temperature and basal melt rates (Vogel and others, 2003; Joughin and others, 2004c, 2009).…”