How Different Analysis and Interpolation Methods Affect the Accuracy of Ice Surface Elevation Changes Inferred from Satellite Altimetry

Satellite altimetry has been widely used to determine surface elevation changes in polar ice sheets. The original height measurements are irregularly distributed in space and time. Gridded surface elevation changes are commonly derived by repeat altimetry analysis (RAA) and subsequent spatial interpolation of height change estimates. This article assesses how methodological choices related to those two steps affect the accuracy of surface elevation changes, and how well this accuracy is represented by formal uncertainties. In a simulation environment resembling CryoSat-2 measurements acquired over a region in northeast Greenland between December 2010 and January 2014, different local topography modeling approaches and different cell sizes for RAA, and four interpolation approaches are tested. Among the simulated cases, the choice of either favorable or unfavorable RAA affects the accuracy of results by about a factor of 6, and the different accuracy levels are propagated into the results of interpolation. For RAA, correcting local topography by an external digital elevation model (DEM) is best, if a very precise DEM is available, which is not always the case. Yet the best DEM-independent local topography correction (nine-parameter model within a 3,000 m diameter cell) is comparable to the use of a perfect DEM, which exactly represents the ice sheet topography, on the same cell size. Interpolation by heterogeneous measurement-error-filtered kriging is significantly more accurate (on the order of 50% error reduction) than interpolation methods, which do not account for heterogeneous errors

Trends in Antarctic Ice Sheet Elevation and Mass

Fluctuations in Antarctic Ice Sheet elevation and mass occur over a variety of time scales, owing to changes in snowfall and ice flow. Here we disentangle these signals by combining 25 years of satellite radar altimeter observations and a regional climate model. From these measurements, patterns of change that are strongly associated with glaciological events emerge. While the majority of the ice sheet has remained stable, 24% of West Antarctica is now in a state of dynamical imbalance. Thinning of the Pine Island and Thwaites glacier basins reaches 122 m in places, and their rates of ice loss are now five times greater than at the start of our survey. By partitioning elevation changes into areas of snow and ice variability, we estimate that East and West Antarctica have contributed −1.1 ± 0.4 and +5.7 ± 0.8 mm to global sea level between 1992 and 201

ANTARCTICA VOLUME CHANGE FROM 10 YEARS OF ENVISAT ALTIMETRY

ISI Document Delivery No.: BDG99 Times Cited: 0 Cited Reference Count: 10 Cited References: Arthern RJ, 2001, J GEOPHYS RES-ATMOS, V106, P33471, DOI 10.1029/2001JD000498 Flament T., 2012, J GLACIO IN PRESS Haran T. J., 2005, MODIS MOSAIC ANTARCT Hurkmans R.T.W.L., 2012, CRYOSPHERE, V6, P447 Joughin I., 2003, GEOPHYS RES LETT, V30 Remy F, 2009, REMOTE SENS-BASEL, V1, P1212, DOI 10.3390/rs1041212 Remy F., 2012, ADV SPACE R IN PRESS Remy F, 2006, IEEE T GEOSCI REMOTE, V44, P3289, DOI 10.1109/TGRS.2006.878444 Riva REM, 2009, EARTH PLANET SC LETT, V288, P516, DOI 10.1016/j.epsl.2009.10.013 Scott JBT, 2009, CRYOSPHERE, V3, P125, DOI 10.5194/tc-3-125-2009 Flament, T. Remy, F. IGARSS Proceedings Paper IEEE International Geoscience and Remote Sensing Symposium (IGARSS) JUL 22-27, 2012 Munich, GERMANY IEEE, IEEE Geosci & Remote Sensing Soc (GRSS), DLR, ESA 345 E 47TH ST, NEW YORK, NY 10017 US