A range correction for ICESat and its potential impact on ice-sheet mass balance studies

被引:81
作者
Borsa, A. A. [1 ]
Moholdt, G. [1 ]
Fricker, H. A. [1 ]
Brunt, K. M. [2 ,3 ]
机构
[1] Scripps Inst Oceanog, San Diego, CA USA
[2] Morgan State Univ, Baltimore, MD 21239 USA
[3] NASA, Goddard Space Flight Ctr, GESTAR, Greenbelt, MD 20771 USA
关键词
RECONCILED ESTIMATE; ALTIMETRY DATA; PRECISION; GREENLAND; ACCURACY; BOLIVIA; UYUNI; SALAR; RADAR;
D O I
10.5194/tc-8-345-2014
中图分类号
P9 [自然地理学];
学科分类号
0705 ; 070501 ;
摘要
We report on a previously undocumented range error in NASA's Ice, Cloud and land Elevation Satellite (ICE-Sat) 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.
引用
收藏
页码:345 / 357
页数:13
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