A four decade record of elevation change of the Amery Ice Shelf, East Antarctica
A four decade record of elevation change of the Amery Ice Shelf, East Antarctica
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DOI：
10.1029/2008jf001094
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发表时间：
2009-03
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影响因子：
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通讯作者：
M. King;R. Coleman;H. Fricker;B. Galton-Fenzi;B. Legrésy;L. Padman;R. Warner
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文献类型：
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作者：
M. King;R. Coleman;H. Fricker;B. Galton-Fenzi;B. Legrésy;L. Padman;R. Warner
[1] 我们通过比较 4 个十年（1968-2007）的海拔记录来报告中部阿默里冰架（AIS）的长期表面海拔变化。我们使用通过以下方法获得的高程记录：光学水准测量（1968-1969）； ERS雷达测高（1992-2003）；全球定位系统（1995-2006）；冰、云和陆地高程卫星（ICESat）激光测高（2003-2007）。我们计算水准路线与每个 GPS 和 ICESat 轨道之间交叉处的多年代际高程趋势 (dh/dt) 值，以及 ERS-ERS、GPS-GPS 和 ICESat-ICESat 交叉处的较短周期 dh/dt。在 GPS 调平交叉处，平均长期 dh/dt 为 −0.003 m a−1，在 ICESat 调平交叉处，平均 dh/dt 为 +0.013 m a−1；这两种趋势都与零没有显着不同。然而，数据确实表现出不同的趋势：1991 年至 1996 年中期变化接近于零，然后增厚至 ∼2003 年，随后在 ∼2003-2007 年变薄，5 年 dh/dt 平均值超过∼±0.1 m a−1。 1996 年中期和 2003 年 dh/dt 模式的变化以意想不到的速度发生。冰架表现出与周围接地冰不同的 dh/dt 模式，这表明表面质量平衡变化或冰致密化过程的长期变化不太可能是主要原因。我们的结论是，这些观察到的多年海拔变化必定是由于目前无法解释或目前量化不佳的涉及地表或基底过程和/或冰动力学的现象造成的。随着 AIS 的数十年稳定性的建立，我们观察到的短期波动表明，对于其他冰架，在短时间内观察到的强 dh/dt 信号并不一定表明冰架不稳定。
[1] We report on long-term surface elevation changes of the central Amery Ice Shelf (AIS) by comparing elevation records spanning 4 decades (1968–2007). We use elevation records acquired with the following methods: optical leveling (1968–1969); ERS radar altimetry (1992–2003); GPS (1995–2006); and Ice, Cloud, and land Elevation Satellite (ICESat) laser altimetry (2003–2007). We compute multidecadal elevation trend (dh/dt) values at crossovers between the leveling route and each of the GPS and ICESat tracks as well as shorter-period dh/dt at ERS-ERS, GPS-GPS, and ICESat-ICESat crossovers. At GPS-leveling crossovers the mean long-term dh/dt is −0.003 m a−1, and at ICESat-leveling crossovers the mean dh/dt is +0.013 m a−1; neither trend is significantly different from zero. The data do, however, exhibit variable trends: near-zero change between 1991 and mid-1996, then thickening to ∼2003, followed by thinning ∼2003–2007, with 5 year dh/dt averages exceeding ∼±0.1 m a−1. The changes in dh/dt pattern in mid-1996 and again in 2003 occur with unexpected speed. The ice shelf exhibits different dh/dt patterns than does the surrounding grounded ice, suggesting that surface mass balance variations or longer-term variations in firn densification processes are unlikely to be major causes. We conclude that these observed multiyear elevation changes must be due to currently unexplained or presently poorly quantified phenomena involving surface or basal processes and/or ice dynamics. With the multidecadal stability of the AIS established, the short-term fluctuations that we observe suggests that for other ice shelves, observed strong dh/dt signals over short time periods do not necessarily indicate ice shelf instability.