How old is the ice beneath Dome A, Antarctica?
How old is the ice beneath Dome A, Antarctica?
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DOI：
10.5194/tc-8-1121-2014
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
Bo Sun;J. Moore;T. Zwinger;Liyun Zhao;D. Steinhage;Xueyuan Tang;Dong Zhang;X. Cui;C. Martín-C.-Mart
中科院分区：
文献类型：
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作者：
Bo Sun;J. Moore;T. Zwinger;Liyun Zhao;D. Steinhage;Xueyuan Tang;Dong Zhang;X. Cui;C. Martín-C.-Mart
不久的将来，中国科学家将在冰穹A附近的昆仑站开始钻探深冰芯。最近的工作预测，Dome A是一个可以发现年龄超过100万年的冰的位置。我们采用三维热力耦合全Stokes模型对昆仑站周围70 dm 2 70 km 2区域的流动、温度和冰的年龄进行了模拟。使用各向同性非线性流变学和不同的规定的各向异性冰组构，所述冰组构从各向同性变化到1/3或2/4处的单一最大值。3个深度。在确定垂直平流时，组构的变化与地热通量的不确定性一样重要，垂直平流随后控制着基底温度和年龄剖面。我们发现，由于冰的厚度变化很大，整个区域的基底年龄变化很大，任何基底融化都会有效地去除冰下山谷最深处的非常古老的冰。与冰盖上部三分之一的测年雷达等时线进行比较，不能充分确定深层冰的年龄，其基底年龄的不确定性高达50万年。我们还评估了基底年龄和热状态对地热通量和地表条件的敏感性。尽管预期在冰穹A的冰川周期中表面高度会发生适度变化，但即使表面条件演变中的微小变化也会导致基底条件发生较大变化，这与雷达调查中看到的基底吸积特征一致。
Chinese scientists will start to drill a deep ice core at Kunlun station near Dome A in the near future. Re- cent work has predicted that Dome A is a location where ice older than 1 million years can be found. We model flow, temperature and the age of the ice by applying a three-dimensional, thermomechanically coupled full-Stokes model to a 70◊ 70 km 2 domain around Kunlun station, us- ing isotropic non-linear rheology and different prescribed anisotropic ice fabrics that vary the evolution from isotropic to single maximum at 1/3 or 2/3 depths. The variation in fabric is about as important as the uncertainties in geothermal heat flux in determining the vertical advection which in con- sequence controls both the basal temperature and the age pro- file. We find strongly variable basal ages across the domain since the ice varies greatly in thickness, and any basal melt- ing effectively removes very old ice in the deepest parts of the subglacial valleys. Comparison with dated radar isochrones in the upper one third of the ice sheet cannot sufficiently con- strain the age of the deeper ice, with uncertainties as large as 500 000 years in the basal age. We also assess basal age and thermal state sensitivities to geothermal heat flux and sur- face conditions. Despite expectations of modest changes in surface height over a glacial cycle at Dome A, even small variations in the evolution of surface conditions cause large variation in basal conditions, which is consistent with basal accretion features seen in radar surveys.