What is GRACE and how does it contribute to GLAS?
The Gravity Recovery and Climate Experiment (GRACE) satellite was launched on 17 March 2002. The mission consists of two satellites in low earth orbit, working together to measure the global gravitational field and document gravity anomalies. The earth's gravity field will be measured more accurately and with higher resolution with GRACE, than from any other previous satellite. Temporal variations inferred from GRACE gravity measurements, combined with GLAS altimetry data, provided a better estimate of changes in ice sheet mass balance for Greenland and Antarctica. Potential error sources in measuring mass balance include uncertainties in postglacial rebound, and under sampling and compaction errors. By combining GLAS and GRACE data, the postglacial rebound error is expected to be reduced (Wahr, Wingham, and Bentley 2000). See Improving GLAS data using GRACE for more information.
Wahr, J., D. Wingham, C. Bentley. 2000. A method of combining ICESat and GRACE satellite data to constrain Antarctic mass balance. Journal of Geophysical Research 105 (B7): 16,279-16,294.