Impact of Sea Ice Drift Retrieval Errors, Discretization and Grid Type on Calculations of Ice Deformation
Impact of Sea Ice Drift Retrieval Errors, Discretization and Grid Type on Calculations of Ice Deformation
复制标题
海冰漂移反演误差、离散化和网格类型对冰变形计算的影响
DOI：
10.3390/rs10030393
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
W. Dierking
中科院分区：
文献类型：
--
作者：
Jakob Griebel;W. Dierking
研究了海冰变形特征参数计算中需要考虑的两个问题：自动反演海冰漂移场中不确定性的影响以及漂移矢量网格类型的影响。海冰变形改变了局部冰质量平衡以及大气、冰和海洋之间的相互作用，并对海上交通和作业构成危害。由于数值效应，变形反演的结果可能会预测现实中不存在的冰盖的打开和闭合。我们特别关注从合成孔径雷达 (SAR) 图像获得的冰漂移场，并分析传播漂移检索误差 (PDRE) 和边界定义误差 (BDE)。根据误差传播理论，可以估计计算出的变形参数的 PDRE。为了量化 BDE，我们设计了五种不同的网格类型，并假设三种情况比较不同变形参数的理论期望和数值结果：纯散度、纯剪切以及两者的混合。我们对这两个误差源的发现有助于建立最佳的变形检索方案，并且对于使用矢量场和由此导出的标量参数的其他应用程序也很有用。
We studied two issues to be considered in the calculation of parameters characterizing sea ice deformation: the effect of uncertainties in an automatically retrieved sea ice drift field, and the influence of the type of drift vector grid. Sea ice deformation changes the local ice mass balance and the interaction between atmosphere, ice, and ocean, and constitutes a hazard to marine traffic and operations. Due to numerical effects, the results of deformation retrievals may predict, e.g., openings and closings of the ice cover that do not exist in reality. We focus specifically on fields of ice drift obtained from synthetic aperture radar (SAR) imagery and analyze the Propagated Drift Retrieval Error (PDRE) and the Boundary Definition Error (BDE). From the theory of error propagation, the PDRE for the calculated deformation parameters can be estimated. To quantify the BDE, we devise five different grid types and compare theoretical expectation and numerical results for different deformation parameters assuming three scenarios: pure divergence, pure shear, and a mixture of both. Our findings for both sources of error help to set up optimal deformation retrieval schemes and are also useful for other applications working with vector fields and scalar parameters derived therefrom.