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CryoSat-2 interferometric mode calibration and validation: A case study from the Austfonna ice cap, Svalbard
Remote Sensing of Environment ( IF 13.5 ) Pub Date : 2021-11-24 , DOI: 10.1016/j.rse.2021.112805
Ashley Morris 1 , Geir Moholdt 1 , Laurence Gray 2 , Thomas Vikhamar Schuler 3, 4 , Trond Eiken 3
Affiliation  

Satellite radar altimetry is widely used to measure glacier and ice sheet elevation changes, but can suffer from uncertainties related to geolocation and signal penetration. The unique capabilities of ESA's CryoSat-2 allow for accurate geolocation but impacts from signal penetration persist. This study uses surface elevations from Global Navigation Satellite System and airborne laser transects over the Austfonna ice cap, Svalbard, to measure the elevation bias of CryoSat-2 Point-of-closest-approach (POCA) and swath points, and to provide validation for dhdt estimates derived through the application of a least-squares plane-fit algorithm to these data. The mean elevation bias of swath points varies between 1 and 1.5 m of penetration, which is close to observed winter snow depths. Histograms of POCA elevation bias for the applied leading-edge retracker peak near the surface, with a distribution skewed towards the sub-surface. At the onset of surface melt, surface scattering dominates backscatter, and penetration reduces. This results in spurious peaks in derived elevation and mass change time series. In spite of this seasonal variability in elevation bias, the validation dhdt dataset demonstrates that the CryoSat-2 dhdt estimates are robust on multi-year timescales. The transition from volume to surface scattering suggests the potential to estimate yearly snowpack thickness.



中文翻译:

CryoSat-2 干涉模式校准和验证:来自斯瓦尔巴群岛 Austfonna 冰盖的案例研究

卫星雷达测高被广泛用于测量冰川和冰盖海拔变化,但可能会受到与地理定位和信号穿透相关的不确定性的影响。ESA 的 CryoSat-2 的独特功能允许进行准确的地理定位,但信号穿透的影响仍然存在。本研究使用全球导航卫星系统的表面高程和斯瓦尔巴群岛 Austfonna 冰盖上的机载激光横断面来测量 CryoSat-2 最近进近点 (POCA) 和条带点的高程偏差,并为天文数字dt通过对这些数据应用最小二乘平面拟合算法得出的估计值。条带点的平均高程偏差在 1 到 1.5  m 的穿透深度之间变化,这接近于观察到的冬季积雪深度。表面附近应用的前沿再跟踪器峰值的 POCA 高程偏差直方图,分布偏向次表面。在表面熔化开始时,表面散射在反向散射中占主导地位,并且渗透率降低。这会导致派生的海拔和质量变化时间序列中出现虚假峰。尽管海拔偏差存在季节性变化,但验证天文数字dt 数据集表明 CryoSat-2 天文数字dt估计数在多年时间尺度上是稳健的。从体积到表面散射的过渡表明估计每年积雪厚度的潜力。

更新日期:2021-11-25
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