Basal mass budget of Ross and Filchner-Ronne ice shelves, Antarctica, derived from Lagrangian analysis of ICESat altimetry
Basal mass budget of Ross and Filchner-Ronne ice shelves, Antarctica, derived from Lagrangian analysis of ICESat altimetry
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DOI：
10.1002/2014jf003171
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发表时间：
2014-11-01
影响因子：
3.9
通讯作者：
Fricker, Helen Amanda
中科院分区：
文献类型：
--
作者：
Moholdt, Geir;Padman, Laurie;Fricker, Helen Amanda
从卫星测高得出南极冰架高程随时间变化的传统方法使用固定的（欧拉）参考框架，其中测量的变化包括测量时期之间冰厚度梯度的平流。我们提出了一种新的方法，通过使用一个独立的速度场比较海拔移动（拉格朗日）参考系，消除平流的影响。应用该技术ICESat激光测高2003-2009年期间在两个最大的南极冰架，罗斯和Filchner-Ronne，我们表明，拉格朗日方法减少了约50%的欧拉方法相比，推导出的海拔变化的变异性，并揭示了更清晰的空间格局的海拔变化。该方法简化了估计基础质量预算的过程中，从剩余的所有其他过程，有助于冰架高程的变化。我们使用现场数据和ICESat测量冰上升和接地冰盖占表面积累和积雪空气含量的变化，并删除冰流发散的影响，使用表面速度和冰厚度数据。结果表明，在主要冰流的深接地线附近，基底融化速率最高（> 5 m a（-1）），但较小的融化速率（
Traditional methods of deriving temporal variability of Antarctic ice-shelf elevation from satellite altimetry use a fixed (Eulerian) reference frame, where the measured changes include advection of ice thickness gradients between measurement epochs. We present a new method which removes advection effects by using an independent velocity field to compare elevations in a moving (Lagrangian) reference frame. Applying the technique to ICESat laser altimetry for the period 2003-2009 over the two largest Antarctic ice shelves, Ross and Filchner-Ronne, we show that the Lagrangian approach reduces the variability of derived elevation changes by about 50% compared to the Eulerian approach and reveals clearer spatial patterns of elevation change. The method simplifies the process of estimating basal mass budget from the residual of all other processes that contribute to ice-shelf elevation changes. We use field data and ICESat measurements over ice rises and the grounded ice sheet to account for surface accumulation and changes in firn air content, and remove the effect of ice-flow divergence using surface velocity and ice thickness data. The results show highest basal melt rates (>5m a(-1)) near the deep grounding lines of major ice streams, but smaller melt rates (