SAR-derived flow velocity and its link to glacier surface elevation change and mass balance
SAR-derived flow velocity and its link to glacier surface elevation change and mass balance
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DOI：
10.1016/j.rse.2021.112343
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发表时间：
2021-06
影响因子：
13.5
通讯作者：
S. Samsonov;K. Tiampo;R. Cassotto
中科院分区：
文献类型：
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作者：
S. Samsonov;K. Tiampo;R. Cassotto
现代遥感技术，如合成孔径雷达（SAR），可以测量冰川流动的方向和强度。然而，问题仍然是这些测量结果揭示了冰川对气候变暖的调整。在这里，我们提出了一种技术，解决这个问题，通过连接SAR派生的速度测量与冰川海拔变化和特定的质量平衡（即每单位面积的质量平衡）。该技术计算斑点偏移跟踪结果从北，东和垂直流位移时间序列，垂直分量进一步分裂成表面平行流（SPF）平流分量，由于运动沿着冰川表面斜坡和非表面平行流（nSPF）。后者将冰川表面高程变化与特定的物质平衡和应变率联系起来。我们将这种技术应用于Sentinel-1数据的上升和下降，以获得2016-2019年阿拉斯加东南部冰川的四维流动位移时间序列。时间序列提取的几个特征区域表现出显着的时间变化的流速。在nSPF分量中观察到的季节性信号使用正度数日模型进行建模。该方法可用于计算物质平衡或冰川表面高程变化，如果这两个参数之一是已知的外部观测。
Modern remote sensing techniques, such as Synthetic Aperture Radar (SAR), can measure the direction and intensity of glacier flow. Yet the question remains as to what these measurements reveal about glaciers' adjustment to the warming climate. Here, we present a technique that addresses this question by linking the SAR-derived velocity measurements with the glacier elevation change and the specific mass balance (i.e. mass balance per unit area). The technique computes the speckle offset tracking results from the north, east and vertical flow displacement time series, with the vertical component further split into a Surface Parallel Flow (SPF) advection component due to the motion along a glacier surface slope and a non-Surface Parallel Flow (nSPF). The latter links the glacier surface elevation change with the specific mass balance and strain rates. We apply this technique to ascending and descending Sentinel-1 data to derive the four-dimensional flow displacement time series for glaciers in southeast Alaska during 2016–2019. Time series extracted for a few characteristic regions demonstrate remarkable temporal variability in flow velocities. The seasonal signal observed in the nSPF component is modeled using the Positive Degree Day model. This method can be used for computing either mass balance or glacier surface elevation change if one of these two parameters is known from external observations.