Remote sensing of glacier change in West Greenland: accounting for the occurrence of surge-type glaciers
Remote sensing of glacier change in West Greenland: accounting for the occurrence of surge-type glaciers
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DOI：
10.3189/172756410790595813
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发表时间：
2009
影响因子：
2.9
通讯作者：
M. Citterio;F. Paul;A. Ahlstrøm;H. Jepsen;A. Weidick
中科院分区：
文献类型：
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作者：
M. Citterio;F. Paul;A. Ahlstrøm;H. Jepsen;A. Weidick
摘要从多光谱卫星数据的阈值波段比自动绘制冰川图是一种成熟的技术，用于更新大范围和偏远地区的冰川清单。格陵兰当地的冰川和冰盖对这类工作特别感兴趣，因为它们只被绘制了部分地图，主要是在20世纪40年代至60年代，它们对全球海平面上升的潜在贡献可能很大。在这里，我们使用了2001年的三个Landsat ETM+场景，覆盖了西格陵兰岛的迪斯科岛(Qeqertarsuaq)和Nuussuaq半岛和Svartenhuk半岛，以绘制2001年1172个实体的冰川范围图。我们还从500个实体的子样本中手动数字化了清晰可见的修剪线的小冰期(LIA)范围。在这个拥有众多涌浪类型冰川的地区，相关的面积变化计算是具有挑战性的，我们考虑了有和没有已知涌动冰川的不同样本。剔除已知涌浪型冰川后，这三个地区的平均面积变化分别为-28%、-20%和-23%。靠近冰盖边缘的较小岛屿和半岛上的冰川平均面积变化较小，为-15%。此外，使用不同的升标假设计算了整个区域在LIA和2001年之间的总体面积变化的下限(-16%)和上限(-21%)。对于波浪型冰川，自LIA以来的累积长度变化被发现略低。
Abstract Automated glacier mapping from thresholded band ratios of multispectral satellite data is a well-established technique to update glacier inventories over large and remote regions. The local glaciers and ice caps on Greenland are of particular interest for such efforts, as they have been only partly mapped, mainly during the 1940s–60s, and their potential contribution to global sea-level rise could be large. Here we use three Landsat ETM+ scenes from 2001 covering Disko Island (Qeqertarsuaq) and the Nuussuaq and Svartenhuk peninsulas, West Greenland, to map the glacier extent in 2001 of 1172 entities. We also manually digitize Little Ice Age (LIA) extents from clearly visible trimlines for a subsample of 500 entities. In this region with numerous surge-type glaciers, the related area-change calculation is challenging and we consider different samples with and without known surging glaciers. For the three regions the mean area changes are –28%, –20% and –23%, respectively, when known surge-type glaciers are excluded. The glaciers on smaller islands and peninsulas closer to the margin of the ice sheet show a lower mean area change of –15%. Moreover, lower (–16%) and upper (–21%) bounds are calculated for the overall area changes in the entire region between the LIA and 2001 using different upscaling assumptions. Cumulative length changes since the LIA are found to be slightly lower for surge-type glaciers.