Two decades of dynamic change and progressive destabilization on the Thwaites Eastern Ice Shelf
Two decades of dynamic change and progressive destabilization on the Thwaites Eastern Ice Shelf
复制标题
DOI：
10.5194/tc-15-5187-2021
复制
发表时间：
2021-11-22
期刊：
影响因子：
5.2
通讯作者：
Dunmire, Devon
中科院分区：
文献类型：
--
作者：
Alley, Karen E.;Wild, Christian T.;Dunmire, Devon
Thwaites东部冰架(Teis)通过与Thwaites冰川向海极限处的一个固定点接触来支撑Thwaites冰川的东部接地部分。冰架的丧失将促进Thwaites冰川的进一步加速。因此，了解Teis的动态控制和结构完整性对于估计Thwaites未来对海平面的贡献非常重要。我们呈现了一个类似于20年来Teis变化的记录，揭示了控制冰架过去行为和正在进行的演变的动态控制。我们分别使用特征跟踪和散斑跟踪从MODIS和Sentinel-1图像数据中提取冰的速度，并将这些记录与来自Landsat-7和Landsat-8的ITS_LIVE和GoLive速度产品相结合。此外，我们使用南极洲参考高程模型(REMA)DEM与ICESat和ICESat-2高度计进行了比较，估计了地表下沉和基本融化速率。在有记录的早期，Teis的流动动态受到邻近的Thwaits-West Ice Lutch(WIT)的强烈控制。在2008年左右TWIT解体后，Teis上的流动模式发生了变化，冰流在其向海极限处的钉点周围形成了新的分流。与此同时，Teis形成了新的裂谷，从冰隆上游的剪切带延伸，并在该剪切带内增加了应变集中。随着这些水平变化的发生，由底部融化驱动的持续变薄减少了冰的厚度，特别是在接地线附近和钉扎点上游的剪切带区域。这一快速减弱的证据表明，Teis很可能在未来几十年内完全不稳定，导致Thwaites冰川进一步加速。
The Thwaites Eastern Ice Shelf (TEIS) buttresses the eastern grounded portion of Thwaites Glacier through contact with a pinning point at its seaward limit. Loss of this ice shelf will promote further acceleration of Thwaites Glacier. Understanding the dynamic controls and structural integrity of the TEIS is therefore important to estimating Thwaites' future sea-level contribution. We present a similar to 20-year record of change on the TEIS that reveals the dynamic controls governing the ice shelf's past behaviour and ongoing evolution. We derived ice velocities from MODIS and Sentinel-1 image data using feature tracking and speckle tracking, respectively, and we combined these records with ITS_LIVE and GOLIVE velocity products from Landsat-7 and Landsat-8. In addition, we estimated surface lowering and basal melt rates using the Reference Elevation Model of Antarctica (REMA) DEM in comparison to ICESat and ICESat-2 altimetry. Early in the record, TEIS flow dynamics were strongly controlled by the neighbouring ThwaitesWestern Ice Tongue (TWIT). Flow patterns on the TEIS changed following the disintegration of the TWIT around 2008, with a new divergence in ice flow developing around the pinning point at its seaward limit. Simultaneously, the TEIS developed new rifting that extends from the shear zone upstream of the ice rise and increased strain concentration within this shear zone. As these horizontal changes occurred, sustained thinning driven by basal melt reduced ice thickness, particularly near the grounding line and in the shear zone area upstream of the pinning point. This evidence of weakening at a rapid pace suggests that the TEIS is likely to fully destabilize in the next few decades, leading to further acceleration of Thwaites Glacier.