Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
The Cryosphere, 8, 345-357, 2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
03 Mar 2014
A range correction for ICESat and its potential impact on ice-sheet mass balance studies
A. A. Borsa1, G. Moholdt1, H. A. Fricker1, and K. M. Brunt2,3 1Scripps Institution of Oceanography, San Diego, California, USA
2Morgan State University, Baltimore, Maryland, USA
3GESTAR, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
Abstract. We report on a previously undocumented range error in NASA's Ice, Cloud and land Elevation Satellite (ICESat) that degrades elevation precision and introduces a small but significant elevation trend over the ICESat mission period. This range error (the Gaussian-Centroid or "G-C" offset) varies on a shot-to-shot basis and exhibits increasing scatter when laser transmit energies fall below 20 mJ. Although the G-C offset is uncorrelated over periods ≤ 1 day, it evolves over the life of each of ICESat's three lasers in a series of ramps and jumps that give rise to spurious elevation trends of −0.92 to −1.90 cm yr−1, depending on the time period considered. Using ICESat data over the Ross and Filchner–Ronne ice shelves we show that (1) the G-C offset introduces significant biases in ice-shelf mass balance estimates, and (2) the mass balance bias can vary between regions because of different temporal samplings of ICESat. We can reproduce the effect of the G-C offset over these two ice shelves by fitting trends to sample-weighted mean G-C offsets for each campaign, suggesting that it may not be necessary to fully repeat earlier ICESat studies to determine the impact of the G-C offset on ice-sheet mass balance estimates.

Citation: Borsa, A. A., Moholdt, G., Fricker, H. A., and Brunt, K. M.: A range correction for ICESat and its potential impact on ice-sheet mass balance studies, The Cryosphere, 8, 345-357,, 2014.
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