Airborne radio-echo sounding (RES) surveys are widely used to measure ice-sheet bed topography. Measuring bed topography as accurately and widely as possible is of critical importance to modelling ice dynamics and hence to constraining better future ice response to climate change. Measurement accuracy of RES surveys is influenced both by the geometry of bed topography and the survey design. Here we develop a novel approach for simulating RES surveys over glaciated terrain, to quantify the sensitivity of derived bed elevation to topographic geometry. Furthermore, we investigate how measurement errors influence the quantification of glacial valley geometry. We find a negative bias across RES measurements, where off-nadir return measurement error is typically −1.8 ± 11.6 m. Topographic highlands are under-measured an order of magnitude more than lowlands. Consequently, valley depth and cross-sectional area are largely under-estimated. While overall estimates of ice thickness are likely too high, we find large glacier valley cross-sectional area to be under-estimated by −2.8 ± 18.1%. Therefore, estimates of ice flux through large outlet glaciers are likely too low when this effect is not taken into account. Additionally, bed mismeasurements potentially impact our appreciation of outlet-glacier stability.

中文翻译：

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机载透冰雷达测量的地理空间模拟揭示了冰盖床地形的高程测量偏差

机载无线电回波探测 (RES) 调查广泛用于测量冰盖床地形。尽可能准确和广泛地测量海床地形对于模拟冰动力学至关重要，从而限制未来冰对气候变化的更好响应。RES 调查的测量精度受到床地形几何和调查设计的影响。在这里，我们开发了一种模拟冰川地形上的 RES 调查的新方法，以量化衍生的床高对地形几何的敏感性。此外，我们研究了测量误差如何影响冰川谷几何形状的量化。我们发现 RES 测量存在负偏差，其中偏离最低点的返回测量误差通常为 -1.8 ± 11.6 m。地形高地比低地被低估了一个数量级。因此，山谷深度和横截面积在很大程度上被低估了。虽然对冰厚度的总体估计可能太高，但我们发现大冰川谷的横截面面积被低估了 -2.8 ± 18.1%。因此，如果不考虑这种影响，通过大型出口冰川的冰通量估计可能太低。此外，床的错误测量可能会影响我们对出口冰川稳定性的评价。如果不考虑这种影响，通过大型出口冰川的冰通量估计可能太低。此外，床的错误测量可能会影响我们对出口冰川稳定性的评价。如果不考虑这种影响，通过大型出口冰川的冰通量估计可能太低。此外，床的错误测量可能会影响我们对出口冰川稳定性的评价。