Impact of bedrock description on modeling ice sheet dynamics
Impact of bedrock description on modeling ice sheet dynamics
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DOI：
10.1029/2011gl048892
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发表时间：
2011-10
影响因子：
5.2
通讯作者：
G. Durand;O. Gagliardini;L. Favier;T. Zwinger;E. L. Meur
中科院分区：
文献类型：
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作者：
G. Durand;O. Gagliardini;L. Favier;T. Zwinger;E. L. Meur
最近的冰川调查显示，从极地冰盖流入海洋的冰量显着增加。与此同时，冰流模型也得到了极大的改进，可以更好地再现当前的变化并预测冰盖的未来行为。对于这些模型，表面地形和基岩高程是关键的输入参数，它们在很大程度上控制着冰盖的动力学和随后的整体质量平衡。由于明显的难以获取的原因，只能获得稀疏且不均匀的基岩高程数据。这些原始数据经过处理后可在常规 5 公里网格上生成数字高程模型 (DEM)。这些 DEM 用于约束所有冰盖模型的基本边界条件。在这里，通过使用全斯托克斯有限元代码，我们检查了冰流模型对基岩描述准确性的敏感性。在短期冰盖预报的背景下，我们表明，在沿海地区，基岩高程的分辨率应为一公里量级。相反，对大陆内部基岩的粗略描述不会影响冰流入海洋的建模。这些发现清楚地表明，在未来的地球物理调查中应优先考虑沿海地区。他们还指出，需要进行范式转变来改变描述冰盖下方基岩的 DEM 的当前设计：它们必须为用户提供将高分辨率基岩高程数据纳入感兴趣区域的机会。
Recent glaciological surveys have revealed a significant increase of ice discharge from polar ice caps into the ocean. In parallel, ice flow models have been greatly improved to better reproduce current changes and forecast the future behavior of ice sheets. For these models, surface topography and bedrock elevation are crucial input parameters that largely control the dynamics and the ensuing overall mass balance of the ice sheet. For obvious reasons of inaccessibility, only sparse and uneven bedrock elevation data is available. This raw data is processed to produce Digital Elevation Models (DEMs) on a regular 5 km grid. These DEMs are used to constrain the basal boundary conditions of all ice sheet models. Here, by using a full‐Stokes finite element code, we examine the sensitivity of an ice flow model to the accuracy of the bedrock description. In the context of short‐term ice sheet forecast, we show that in coastal regions, the bedrock elevation should be known at a resolution of the order of one kilometer. Conversely, a crude description of the bedrock in the interior of the continent does not affect modeling of the ice outflow into the ocean. These findings clearly indicate that coastal regions should be prioritized during future geophysical surveys. They also indicate that a paradigm shift is required to change the current design of DEMs describing the bedrock below the ice sheets: they must give users the opportunity to incorporate high‐resolution bedrock elevation data in regions of interest.