文章基本信息

标题：Error sources in basal yield stress inversions for Jakobshavn Isbræ, Greenland, derived from residual patterns of misfit to observations
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作者：MARIJKE HABERMANN ; MARTIN TRUFFER ; DAVID MAXWELL 等
期刊名称：Journal of Glaciology
印刷版ISSN：0022-1430
电子版ISSN：1727-5652
出版年度：2017
卷号：63
期号：242
页码：999-1011
DOI：10.1017/jog.2017.61
出版社：Cambridge University Press
摘要：ABSTRACT The basal interface of glaciers is generally not directly observable. Geophysical inverse methods are therefore used to infer basal parameters from surface observations. Such methods can also provide information about potential inadequacies of the forward model. Ideally an inverse problem can be regularized so that the differences between modeled and observed surface velocities reflect observational errors. However, deficiencies in the forward model usually result in additional errors. Here we use the spatial pattern of velocity residuals to discuss the main error sources for basal stress inversions for Jakobshavn Isbræ, Greenland. Synthetic tests with prescribed patterns of basal yield stress with varying length scales are then used to investigate different weighting functions for the data-model misfit and for the ability of the inversion to resolve details in basal yield stress. We also test real-data inversions for their sensitivities to prior estimate, forward model parameters, data gaps, and temperature fields. We find that velocity errors are not sufficient to explain the residual patterns of real-data inversions. Conversely, ice-geometry errors and especially simulated errors in model simplifications are capable of reproducing similar error patterns and magnitudes. We suggest that residual patterns can provide useful guidance for forward model improvements.
关键词：glacier modeling;ice; sheet modeling;subglacial processes