Assessing the Current Evolution of the Greenland I

Authors: A Groh H Ewert M Fritsche A Rülke R Rosenau M Scheinert R Dietrich

Publish Date: 2014/03/20

Volume: 35, Issue: 6, Pages: 1459-1480

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Abstract

The present study utilises different satellite and groundbased geodetic observations in order to assess the current evolution of the Greenland Ice Sheet GIS Satellite gravimetry data acquired by the Gravity Recovery and Climate Experiment are used to derive icemass changes for the period from 2003 to 2012 The inferred time series are investigated regarding longterm seasonal and interannual variations Laser altimetry data acquired by the Ice Cloud and land Elevation Satellite ICESat are utilised to solve for linear and seasonal changes in the icesurface height and to infer independent masschange estimates for the entire GIS and its major drainage basins We demonstrate that common signals can be identified in the results of both sensors Moreover the analysis of a Global Positioning System GPS campaign network in West Greenland for the period 1995–2007 allows us to derive crustal deformation caused by glacial isostatic adjustment GIA and by presentday icemass changes ICESatderived elastic crustal deformations are evaluated comparing them with GPSobserved uplift rates which were corrected for the GIA effect inferred by model predictions Existing differences can be related to the limited resolution of ICESat Such differences are mostly evident in dynamical regions such as the Disko Bay region including the rapidly changing Jakobshavn Isbræ which is investigated in more detail Glacier flow velocities are inferred from satellite imagery yielding an accelerated flow from 1999 to 2012 Since our GPS observations cover a period of more than a decade changes in the vertical uplift rates can also be investigated It turns out that the increased mass loss of the glacier is also reflected by an accelerated vertical upliftThis work was supported by the German Research Foundation DFG within the Priority Programme SPP1257 “Mass Transport and Mass Distribution in the Earth System” Our spherical harmonic analyses were performed using the freely available software archive SHTOOLS shtoolsipgpfr The GIA model predictions were calculated using the software package SELEN Spada and Stocchi 2007 All figures were generated by means of the freely available Generic Mapping Tools Wessel and Smith 1998 We gratefully acknowledge the comments by two anonymous reviewers which helped to improve the original manuscript

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