Fusion of Multi-Sensor Surface Elevation Data to Reconstruct Surface Elevation Changes over Zachariæ Isstrøm, Northeast Greenland, 2001-2013

Abstract:

For the past two decades surface elevation data has been gathered over the Greenland Ice Sheet (GrIS) by airborne and satellite laser altimetry. Moreover, surface elevation data and elevation changes have increasingly become available from a variety of stereographic Digital Elevation Models (DEMs), generated, for example from ASTER, SPOT and WorldView imaging sensors. Laser altimeters provide accurate surface elevation measurements, but have relatively low spatial and temporal resolutions over the majority of the GrIS. DEMs, however, have lower vertical accuracy but high spatial resolution. The fusion of these data sets allows for the generation of a detailed and accurate spatio-temporal history of elevation changes.

Recent studies have shown that mass loss in Northeast Greenland, in particular from the outlet glaciers draining the Northeast Greenland Ice Stream (NEGIS), has been increasing. Having an ice plain with a bed situated well below sea level makes Zachariæ Isstrøm, one of the main outlet glaciers of the NEGIS, vulnerable to rapid thinning and retreat.

The fusion of multi-sensor surface elevation data over the Zachariæ Isstrøm during the period of 2001-2013 provides an accurate history of elevation changes and demonstrates that the onset of thinning occurred earlier than previously thought. It also allows for improving the predictions of future mass loss and corresponding sea level rise.