Weekly Mapping of Sea Ice Freeboard in the Ross Sea from ICESat-2
Weekly Mapping of Sea Ice Freeboard in the Ross Sea from ICESat-2
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DOI：
10.3390/rs13163277
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
YoungHyun Koo;H. Xie;N. Kurtz;S. Ackley;Alberto M. Mestas-Nuñez
中科院分区：
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作者：
YoungHyun Koo;H. Xie;N. Kurtz;S. Ackley;Alberto M. Mestas-Nuñez
自2018年10月以来，NASA的ICESat-2一直在提供极地地区的海冰干舷测量。尽管ICESat-2具有出色的空间分辨率和精度，但数据的空间稀疏性可能是海冰监测的一个关键问题。本研究采用了地质统计方法（即，普通克里金法）来表征ICESat-2干舷测量值（ATL 10）的空间自相关性，以估计整个罗斯海地区2019年的每周干舷变化，包括ICESat-2轨道无法直接获得的地方。在这项研究中，三个变异函数模型（指数，高斯和球形）进行了比较。根据交叉验证结果，克里金法估算的干舷与实际ATL 10干舷测量值的相关系数为0.56-0.57，均方根误差（RMSE）为~0.12 m，平均绝对误差（MAE）为~0.07 m。此外，克里金插值的估计误差在秋季低，冬春季高，罗斯海南部低，北方高。变异函数的有效范围为5-10 km，三种变异函数模型的结果没有显示出显著差异。罗斯海的西南（SW）部分全年表现出低而一致的干舷，因为在该部分经常开放宽冰间湖地区产生新的冰。然而，东南（SE）部门显示干舷的变化很大，这表明了从阿蒙森海到罗斯海的厚多年冰平流。因此，ICESat-2干舷的这种基于克里金法的内插可以在未来通过结合其他遥感数据来准确估计罗斯海的海冰产量。
NASA’s ICESat-2 has been providing sea ice freeboard measurements across the polar regions since October 2018. In spite of the outstanding spatial resolution and precision of ICESat-2, the spatial sparsity of the data can be a critical issue for sea ice monitoring. This study employs a geostatistical approach (i.e., ordinary kriging) to characterize the spatial autocorrelation of the ICESat-2 freeboard measurements (ATL10) to estimate weekly freeboard variations in 2019 for the entire Ross Sea area, including where ICESat-2 tracks are not directly available. Three variogram models (exponential, Gaussian, and spherical) are compared in this study. According to the cross-validation results, the kriging-estimated freeboards show correlation coefficients of 0.56–0.57, root mean square error (RMSE) of ~0.12 m, and mean absolute error (MAE) of ~0.07 m with the actual ATL10 freeboard measurements. In addition, the estimated errors of the kriging interpolation are low in autumn and high in winter to spring, and low in southern regions and high in northern regions of the Ross Sea. The effective ranges of the variograms are 5–10 km and the results from the three variogram models do not show significant differences with each other. The southwest (SW) sector of the Ross Sea shows low and consistent freeboard over the entire year because of the frequent opening of wide polynya areas generating new ice in this sector. However, the southeast (SE) sector shows large variations in freeboard, which demonstrates the advection of thick multiyear ice from the Amundsen Sea into the Ross Sea. Thus, this kriging-based interpolation of ICESat-2 freeboard can be used in the future to estimate accurate sea ice production over the Ross Sea by incorporating other remote sensing data.