Satellite altimetry has been widely used to determine surface elevation changes in polar ice sheets. The original height measurements are irregularly distributed in space and time. Gridded surface elevation changes are commonly derived by repeat altimetry analysis (RAA) and subsequent spatial interpolation of height change estimates. This article assesses how methodological choices related to those two steps affect the accuracy of surface elevation changes, and how well this accuracy is represented by formal uncertainties. In a simulation environment resembling CryoSat-2 measurements acquired over a region in northeast Greenland between December 2010 and January 2014, different local topography modeling approaches and different cell sizes for RAA, and four interpolation approaches are tested. Among the simulated cases, the choice of either favorable or unfavorable RAA affects the accuracy of results by about a factor of 6, and the different accuracy levels are propagated into the results of interpolation. For RAA, correcting local topography by an external digital elevation model (DEM) is best, if a very precise DEM is available, which is not always the case. Yet the best DEM-independent local topography correction (nine-parameter model within a 3,000 m diameter cell) is comparable to the use of a perfect DEM, which exactly represents the ice sheet topography, on the same cell size. Interpolation by heterogeneous measurement-error-filtered kriging is significantly more accurate (on the order of 50% error reduction) than interpolation methods, which do not account for heterogeneous errors.

中文翻译：

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不同的分析和内插方法如何影响从卫星测高仪推断出的冰面高程变化的准确性

卫星测高仪已被广泛用于确定极地冰盖的表面高度变化。原始的高度测量值在时间和空间上分布不规则。网格化的表面高程变化通常是通过重复测高分析（RAA）和高度变化估计值的后续空间插值得出的。本文评估了与这两个步骤相关的方法选择如何影响表面高程变化的准确性，以及这种准确性如何用形式上的不确定性表示。在2010年12月至2014年1月之间在格陵兰东北部某个地区获得的类似于CryoSat-2测量值的模拟环境中，测试了不同的局部地形建模方法和不同的RAA像元大小，并测试了四种插值方法。在模拟案例中，选择合适的RAA或不利的RAA都会对结果的准确性造成大约6倍的影响，并且不同的准确性级别会传播到插值结果中。对于RAA，如果可以使用非常精确的DEM，则最好使用外部数字高程模型（DEM）校正局部地形，但情况并非总是如此。然而，最佳的独立于DEM的局部地形校正（直径为3000 m的单元中的九参数模型）与在相同单元大小下使用完全代表冰盖地形的完美DEM相当。与不考虑异构误差的内插方法相比，使用异构测量误差滤波的克里格插值进行的内插方法要准确得多（误差减少约50％）。