Ice discharge uncertainties in Northeast Greenland from boundary conditions and climate forcing of an ice flow model
Ice discharge uncertainties in Northeast Greenland from boundary conditions and climate forcing of an ice flow model
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冰流模型的边界条件和气候强迫导致格陵兰岛东北部的冰流量不确定性
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
J. Box
中科院分区：
文献类型：
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作者：
N. Schlegel;E. Larour;H. Seroussi;Mathieu Morlighem;J. Box
为了了解冰盖对气候变化的响应，检查与冰流模型边界条件和强迫有关的误差是至关重要的。了解这些误差如何通过数值冰盖模式传播并导致模式输出的不确定性也很重要。利用在冰盖系统模式(ISSM)中建立的不确定性量化方法，研究了东北格陵兰冰流(NEGIS)内冰流对包括冰黏度和基面阻力在内的关键场的敏感性，并将其与模式对气候强迫的敏感性进行了比较。此外，我们还考察了在1989至2010年的NEGIS正向模拟期间，模型输入的误差如何表现为质量通量不确定性。总体而言，我们发现，质量通量在主要出口NioghalvfJerdsbræ和ZachariæIsstróm最不确定，质量通量对基础阻力最敏感，尽管与基础阻力相关的误差约束较差，难以量化。鉴于我们对与冰的热性质有关的误差的了解，我们估计，在消融区，低温水文变暖的影响造成的质量通量不确定度是地热热通量误差的4倍以上。我们发现，由于地热通量的误差，NEGIS的总冰流量与0.7GT/年(2.6%)的不确定度和3.3GT/年(11.6%)的不确定度由于冰冻水文变暖的附加影响有关。相比之下，地表质量平衡误差对NEGIS总流量的不确定度贡献为4.5Gt/年。
In order to understand ice sheet response to climate change, it is critical to examine errors associated with ice flow model boundary conditions and forcing. It is also important to understand how these errors propagate through numerical ice sheet models and contribute to uncertainty in model output. Using established uncertainty quantification methods within the Ice Sheet System Model (ISSM), we investigate the sensitivity of ice flow within the Northeast Greenland Ice Stream (NEGIS) to key fields, including ice viscosity and basal drag, and compare them with model sensitivity to climate forcing. In addition, we examine how errors in model input manifest as mass flux uncertainties during a forward simulation of the NEGIS from 1989 to 2010. Overall, we find that mass flux is most uncertain in the main outlets, Nioghalvfjerdsbræ and Zachariæ Isstrøm, and that mass flux is most sensitive to basal drag, though errors associated with basal drag are poorly constrained and difficult to quantify. Given our knowledge of errors associated with the thermal properties of ice, we estimate that in the ablation area, the effects of cryohydrologic warming contribute over 4 times more mass flux uncertainty that do errors in geothermal heat flux. We find that NEGIS total ice discharge is associated with a 0.7 Gt/yr (2.6%) uncertainty due to errors in geothermal heat flux and a 3.3 Gt/yr (11.6%) uncertainty due to the added effects of cryohydrologic warming. In comparison, errors in surface mass balance contribute 4.5 Gt/yr to NEGIS total discharge uncertainty.
影响因子：
18.3
作者：
Bartholomew, Ian;Nienow, Peter;Sole, Andrew
通讯作者：
Sole, Andrew