A Method to Improve High-Resolution Sea Ice Drift Retrievals in the Presence of Deformation Zones
A Method to Improve High-Resolution Sea Ice Drift Retrievals in the Presence of Deformation Zones
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DOI：
10.3390/rs9070718
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发表时间：
2017-07
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影响因子：
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通讯作者：
Jakob Griebel;W. Dierking
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文献类型：
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作者：
Jakob Griebel;W. Dierking
从高空间分辨率的合成孔径雷达(SAR)图像中提取海冰漂移信息，对于了解海冰在不同空间尺度上的运动行为和变形过程具有重要意义。冰的变形会导致SAR图像序列中观测到的模式在时间上发生变化，这使得基于相关和特征识别技术的算法难以提取冰位移量。这里，我们对模式匹配算法提出了两个扩展，目的是提高在几百米空间分辨率下反演的海冰漂移场的可靠性。首先，我们扩展了先前研究中提出的一种可靠性评估方法，该方法基于对合成孔径雷达图像对的纹理和相关参数的分析，旨在排除不可靠的模式匹配。第二步特别适应于变形特征的存在，以避免擦除漂移场中的不连续。我们提出了一种自适应的检测方案，该方案识别漂移向量场中的线性变形特征(LDF)，并在考虑到此类LDF在其邻域中的存在后检测和替换离群点。通过比较自动恢复的漂移数据和人工获取的不同海冰覆盖区域三个场景的参考数据，验证了模式匹配算法的改进。
Retrievals of sea ice drift from synthetic aperture radar (SAR) images at high spatial resolution are valuable for understanding kinematic behavior and deformation processes of the ice at different spatial scales. Ice deformation causes temporal changes in patterns observed in sequences of SAR images; which makes it difficult to retrieve ice displacement with algorithms based on correlation and feature identification techniques. Here, we propose two extensions to a pattern matching algorithm, with the objective to improve the reliability of the retrieved sea ice drift field at spatial resolutions of a few hundred meters. Firstly, we extended a reliability assessment proposed in an earlier study, which is based on analyzing texture and correlation parameters of SAR image pairs, with the aim to reject unreliable pattern matches. The second step is specifically adapted to the presence of deformation features to avoid the erasing of discontinuities in the drift field. We suggest an adapted detection scheme that identifies linear deformation features (LDFs) in the drift vector field, and detects and replaces outliers after considering the presence of such LDFs in their neighborhood. We validate the improvement of our pattern matching algorithm by comparing the automatically retrieved drift to manually derived reference data for three SAR scenes acquired over different sea ice covered regions.