Modeling subglacial water routing at Paakitsoq, W Greenland
Modeling subglacial water routing at Paakitsoq, W Greenland
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DOI：
10.1002/jgrf.20093
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发表时间：
2013-09-01
影响因子：
3.9
通讯作者：
Arnold, Neil S.
中科院分区：
文献类型：
--
作者：
Banwell, Alison F.;Willis, Ian C.;Arnold, Neil S.
格陵兰冰盖冰下排水系统的功能及其对冰动态的影响主要是从假设的水文动力学模型和卫星数据分析以及现场全球定位系统测量推断出来的。尽管如此，地表水文如何与冰下排水系统相互作用，影响基底水压力和冰流量，特别是在年度时间尺度上，仍然存在不确定性。为了解决这个问题，我们开发了一个高空间（100米）和时间（1小时）分辨率，分布式，物理为基础的，冰下水文模型，并将其应用到帕基索克地区，格陵兰岛西部。该模型是驱动与冰川臼输入过程线计算的表面路由和湖泊填充/排水模型，被迫最终与分布的每小时径流计算的表面质量平衡模型。该模型的主要输出是空间和时间上变化的冰下水压力和冰前河流历线。在融化季节的早期，由于湖泊排水事件，水压的短峰值持续不到一天。在仲夏，即使在冰下系统被推断为主要有效的时候，也会有持续数天至数周的高水压。在夏季后期，水压出现较大的昼夜波动，峰值经常超过覆冰压力，并逐渐下降。这些现象支持了以前的假设建模工作的结果和从GPS测量得出的推论。
The functioning of the Greenland Ice Sheet's subglacial drainage system and its effect on ice dynamics have been inferred largely from hypothetical hydrology dynamics models and from analysis of satellite data and in situ GPS measurements. Despite this, there is still uncertainty about how the surface hydrology interacts with the subglacial drainage system and affects basal water pressures and ice flow, especially over annual time scales. To address this, we developed a high spatial (100m) and temporal (1h) resolution, distributed, physically based, subglacial hydrological model, and applied it to the Paakitsoq region, western Greenland. The model is driven with moulin input hydrographs calculated by a surface routing and lake filling/draining model, forced ultimately with distributed hourly runoff calculated by a surface mass balance model. Key outputs from the model are spatially and temporally varying subglacial water pressures and proglacial stream hydrographs. Early in the melt season, short spikes in water pressure lasting less than a day occur as a result of lake drainage events. During midsummer, there are sustained periods of high water pressure lasting days to weeks, even at times when the subglacial system is inferred to be predominantly efficient. Later in the summer, large diurnal fluctuations in water pressure occur with peaks regularly exceeding ice overburden pressure superimposed on a gradually declining trend. These phenomena support the results of previous hypothetical modeling efforts and inferences drawn from GPS measurements.