Holocene accumulation and ice sheet dynamics in central West Antarctica
Holocene accumulation and ice sheet dynamics in central West Antarctica
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南极洲西部中部全新世堆积和冰盖动态
DOI：
10.1029/2007jf000764
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发表时间：
2008
影响因子：
--
通讯作者：
Morse, D. L.
中科院分区：
文献类型：
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作者：
Neumann, T. A.;Conway, H.;Price, S. F.;Waddington, E. D.;Catania, G. A.;Morse, D. L.
我们通过跟踪雷达探测到的伯德冰芯层和裂口附近105米的冰芯，得出了罗斯海和阿蒙森海之间冰鸿沟的深度-年龄关系。深度-年龄关系和冰流模型用于建立过去8000年的积累历史和冰盖动力学。结果表明，在5000至3000年前，积累量比今天高出约30%。今天的南极气候变率主要受环极涡旋强度的周期性波动所支配，这提出了涡旋在高积累期间系统地变弱的可能性。如今，财富积累几乎呈线性递减。这种模式不太可能在全新世发生改变。雷达探测的地层学显示，没有证据表明在一个稳定的被冻结到床上的分水岭下存在拱形层，这意味着该分水岭也在迁移和/或基底冰在全新世一直在滑动。我们不能排除滑动的可能性，因为基底冰已接近其压力熔点。其他证据表明分化迁移是可能的。罗斯海区域现在接近稳定状态，但在200年前Kamb冰流活跃时，罗斯海区域存在强烈的负不平衡。相比之下，最近松岛冰川和思韦茨冰川的加速可能导致阿蒙森海区域的物质平衡变为负值。今天，这条分界线很可能向罗斯海移动。
We derive depth‐age relationships across the ice divide between the Ross and Amundsen Seas by tracking radar‐detected layers from the Byrd ice core and a dated 105‐m core near the divide. The depth‐age relationships and an ice‐flow model are used to establish histories of accumulation and ice sheet dynamics over the past 8000 years. Results show that accumulation was approximately 30% higher than today from 5000 to 3000 years ago. Antarctic climate variability today is dominated by periodic fluctuations in strength of the circumpolar vortex, which raises the possibility that the vortex was systematically weaker during the period of high accumulation. Accumulation today decreases almost linearly across the divide. It is unlikely that this pattern has changed through the Holocene. The radar‐detected stratigraphy shows no evidence of the arched layers that are expected beneath a stable divide that is frozen to its bed, implying that the divide has also been migrating and/or the basal ice has been sliding through the Holocene. We cannot rule out the possibility of sliding because the basal ice is near its pressure melting point. Other evidence indicates that divide migration is likely. The Ross Sea sector is now near steady state, but it had a strong negative imbalance 200 years ago when Kamb Ice Stream was active. In contrast, recent speedups of Pine Island and Thwaites Glaciers have likely caused the mass balance of the Amundsen Sea sector to become negative. The divide is likely migrating toward the Ross Sea today.