Inferred basal friction and surface mass balance of the Northeast Greenland Ice Stream using data assimilation of ICESat (Ice Cloud and land Elevation Satellite) surface altimetry and ISSM (Ice Sheet System Model)
Inferred basal friction and surface mass balance of the Northeast Greenland Ice Stream using data assimilation of ICESat (Ice Cloud and land Elevation Satellite) surface altimetry and ISSM (Ice Sheet System Model)
复制标题
利用ICESat（冰云和陆地高程卫星）表面测高和ISSM（冰盖系统模型）的数据同化推断格陵兰岛东北部冰流的基底摩擦力和表面质量平衡
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
A. Khazendar
中科院分区：
文献类型：
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作者：
E. Larour;J. Utke;B. Csathó;A. Schenk;H. Seroussi;Mathieu Morlighem;E. Rignot;N. Schlegel;A. Khazendar
摘要。在冰盖系统模型（ISSM）框架内提出了一种新的数据同化方法，该方法能够将来自ICESat（冰云和陆地高程卫星）等任务的地表高度数据同化到瞬态冰流的重建中。新方法依靠算法微分来计算目标函数相对于模型强迫的梯度。它被应用于格陵兰岛东北冰流，在那里，地表质量平衡和基础摩擦强迫在时间上被反转，从而产生最适合现有测高的调整后的模拟地表高度。这种新方法可以更好地量化基础和地表过程，并更好地理解目前在瞬态冰流模型中缺失的物理过程，从而更好地捕捉地表高度的重要年际变化。它还表明，地表质量平衡和基础摩擦等模式强迫需要很大的时空变异性，这种变异性只能通过包括表面积雪压实和冰盖底部基础水文等更复杂的过程来解释。这种方法确实是朝着吸收EnviSat、ICESat、冰桥行动和CryoSat-2提供的丰富的高空间分辨率测高数据迈出的第一步，这些数据将在不久的将来随着ICESat-2的发射而提供。
Abstract. We present a new data assimilation method within the Ice Sheet System Model (ISSM) framework that is capable of assimilating surface altimetry data from missions such as ICESat (Ice Cloud and land Elevation Satellite) into reconstructions of transient ice flow. The new method relies on algorithmic differentiation to compute gradients of objective functions with respect to model forcings. It is applied to the Northeast Greenland Ice Stream, where surface mass balance and basal friction forcings are temporally inverted, resulting in adjusted modeled surface heights that best fit existing altimetry. This new approach allows for a better quantification of basal and surface processes and a better understanding of the physical processes currently missing in transient ice-flow models to better capture the important intra- and interannual variability in surface altimetry. It also demonstrates that large spatial and temporal variability is required in model forcings such as surface mass balance and basal friction, variability that can only be explained by including more complex processes such as snowpack compaction at the surface and basal hydrology at the bottom of the ice sheet. This approach is indeed a first step towards assimilating the wealth of high spatial resolution altimetry data available from EnviSat, ICESat, Operation IceBridge and CryoSat-2, and that which will be available in the near future with the launch of ICESat-2.
影响因子：
5.2
作者：
A. Shepherd;A. Hubbard;P. Nienow;Matt A. King;M. McMillan;I. Joughin
通讯作者：
A. Shepherd;A. Hubbard;P. Nienow;Matt A. King;M. McMillan;I. Joughin