Fig nbsp xA A Binary locations

Fig. 4. Rate of elevation change [m/yr] of the GrIS above the ELA derived from 2003 to 09 ICESat (a) and Envisat (b) data, respectively. (c) The difference between the rate of elevation change seen from ICESat and Envisat (Eq. (2)). The areas Z1–Z4 indicate zones of interest for the interpretation of the results. All data sets have been smoothed by DHEA Gaussian filter with a radius of 25 km to suppress short wavelengths.Figure optionsDownload full-size imageDownload high-quality image (522 K)Download as PowerPoint slide
In terms of rate of elevation change above the ELA, ICESat shows a thinning of the southeastern and northwestern margins of the GrIS and a slight thickening in the interior (Fig. 4a). The thickening is trichomes most pronounced in Northeast GrIS and also northwest of the South Dome. A similar pattern is found in the Envisat results, however here a band of thinning is observed across the GrIS from the catchment area of Jakobshavn Isbræ in the west to the catchment area of the Kangerdlussuaq glacier in the east. Fig. 4c shows the difference between the rate of elevation change based on Envisat and ICESat data above the ELA, given byequation(2)dHdtΔ=dHdtICESat−dHdtEnvisat.