Impacts of snow data and processing methods on the interpretation of long-term changes in Baffin Bay early spring sea ice thickness
Impacts of snow data and processing methods on the interpretation of long-term changes in Baffin Bay early spring sea ice thickness
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DOI：
10.5194/tc-15-4909-2021
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发表时间：
2021-10
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影响因子：
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通讯作者：
I. Glissenaar;J. Landy;A. Petty;N. Kurtz;J. Stroeve
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文献类型：
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作者：
I. Glissenaar;J. Landy;A. Petty;N. Kurtz;J. Stroeve
抽象。在北极，多年海冰正在迅速被季节性海冰所取代。巴芬湾位于格陵兰岛和加拿大之间，是季节性冰区的一部分。在这项研究中，我们提出了一个长期的多任务评估（2003-2020年）的春季海冰厚度在巴芬湾卫星测高和海冰图。巴芬湾内的海冰厚度是根据Envisat、ICESat、CryoSat-2和ICESat-2的干舷估计值计算的，同时还有一个与测高数据密切匹配的冰图开发阶段的代理。我们研究海冰厚度的敏感性，估计从一系列不同的雪深和雪密度产品和方法重新分配低分辨率的雪数据到沿跟踪测高干舷。雪深产品，应用包括参考估计沃伦气候，被动微波雪深产品，和动态雪计划SnowModel-LG. We发现，应用雪深重新分布，以代表小规模的雪的变化有相当大的影响，冰厚度计算从激光干舷，但雷达干舷是不必要的。决定使用哪种雪荷载产品以及是否应用雪再分布可以导致关于趋势和物理机制的不同结论。例如，对于不同的雪深/密度产品和再分布方法，我们发现3月份平均海冰厚度为13%的不确定性包络。因此，2003年至2020年3月海冰厚度的趋势范围为每十年-23至17厘米，这取决于所采用的雪深/密度产品和再分布方法。从1996年以来的较长时间尺度来看，代理冰厚图产品显示，巴芬湾内的冰厚在统计上显著减少，每十年减少7厘米。我们的研究为巴芬湾海冰厚度自2003年以来的长期不对称趋势提供了进一步的证据（海湾西部每十年变薄-17.6厘米，东部每十年变厚10.8厘米）。这种不对称的变薄对于雪产品和加工方法的所有组合都是一致的，但目前还不清楚是什么导致了这些变化。
Abstract. In the Arctic, multi-year sea ice is being rapidly replaced by seasonal sea ice. Baffin Bay, situated between Greenland and Canada, is part of the seasonal ice zone. In this study, we present a long-term multi-mission assessment (2003–2020) of spring sea ice thickness in Baffin Bay from satellite altimetry and sea ice charts. Sea ice thickness within Baffin Bay is calculated from Envisat, ICESat, CryoSat-2, and ICESat-2 freeboard estimates, alongside a proxy from the ice chart stage of development that closely matches the altimetry data. We study the sensitivity of sea ice thickness results estimated from an array of different snow depth and snow density products and methods for redistributing low-resolution snow data onto along-track altimetry freeboards. The snow depth products that are applied include a reference estimated from the Warren climatology, a passive microwave snow depth product, and the dynamic snow scheme SnowModel-LG. We find that applying snow depth redistribution to represent small-scale snow variability has a considerable impact on ice thickness calculations from laser freeboards but was unnecessary for radar freeboards. Decisions on which snow loading product to use and whether to apply snow redistribution can lead to different conclusions on trends and physical mechanisms. For instance, we find an uncertainty envelope around the March mean sea ice thickness of 13 % for different snow depth/density products and redistribution methods. Consequently, trends in March sea ice thickness from 2003–2020 range from −23 to 17 cm per decade, depending on which snow depth/density product and redistribution method is applied. Over a longer timescale, since 1996, the proxy ice chart thickness product has demonstrated statistically significant thinning within Baffin Bay of 7 cm per decade. Our study provides further evidence for long-term asymmetrical trends in Baffin Bay sea ice thickness (with −17.6 cm per decade thinning in the west and 10.8 cm per decade thickening in the east of the bay) since 2003. This asymmetrical thinning is consistent for all combinations of snow product and processing method, but it is unclear what may have driven these changes.