Assimilating the ICE‐6G_C Reconstruction of the Latest Quaternary Ice Age Cycle Into Numerical Simulations of the Laurentide and Fennoscandian Ice Sheets
Assimilating the ICE‐6G_C Reconstruction of the Latest Quaternary Ice Age Cycle Into Numerical Simulations of the Laurentide and Fennoscandian Ice Sheets
复制标题
将最新第四纪冰期循环的 ICE-6G_C 重建同化到劳伦泰德和芬诺斯坎迪亚冰盖的数值模拟中
DOI：
10.1002/2017jf004359
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
andW. R. Peltier
中科院分区：
文献类型：
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作者：
G. Stuhne;andW. R. Peltier
我们分析了 Laurentide 和 Fennoscandian 冰盖的 100 kyr 数值模拟对基于冰川均衡调整（基于 GIA）的 ICE-6G_C 重建最近冰河时代周期的影响。从 PISM 冰盖模型的冰物理近似和 SeaRISE 模拟协议开始，我们通过冰质量守恒方程中的反常质量平衡项，在特征时间尺度 τf 上加入微推。正如预期的那样，当微推非常强时（北美 τf=20 年），这些质量平衡表现出由纯基于 GIA 的重建几何产生的物理上不切实际的细节，而微弱微推（τf=1,000 年）解决方案与 ICE‐6G_C 的偏差足以降低其观测拟合质量。对于合理的中间时间尺度（τf = 100年和200年），我们扰动地分析微动冰动力学作为“前阶平滑”的叠加，以物理和观测一致的方式扩散ICE-6G_C，以及例如由地表气候边界条件的时间依赖性偏差引起的“高阶”偏差。基于各个微调模拟之间的相对偏差，其中这些偏差遵循冰芯的表面温度和海洋沉积物核心的海平面上升，我们计算“冰芯气候调整”，建议如何将当地古气候观测应用于 ICE-6G_C 的系统细化。我们的结果与越来越多的证据相一致，表明融水脉冲 1B (MWP1b) 的地理起源可能主要位于北美，而不是南极洲（如 ICE-6G_C 中重建的）。
We analyze the effects of nudging 100 kyr numerical simulations of the Laurentide and Fennoscandian ice sheets toward the glacial isostatic adjustment‐based (GIA‐based) ICE‐6G_C reconstruction of the most recent ice age cycle. Starting with the ice physics approximations of the PISM ice sheet model and the SeaRISE simulation protocols, we incorporate nudging at characteristic time scales, τf, through anomalous mass balance terms in the ice mass conservation equation. As should be expected, these mass balances exhibit physically unrealistic details arising from pure GIA‐based reconstruction geometry when nudging is very strong (τf=20 years for North America), while weakly nudged (τf=1,000 years) solutions deviate from ICE‐6G_C sufficiently to degrade its observational fit quality. For reasonable intermediate time scales (τf=100 years and 200 years), we perturbatively analyze nudged ice dynamics as a superposition of “leading‐order smoothing” that diffuses ICE‐6G_C in a physically and observationally consistent manner and “higher‐order” deviations arising, for instance, from biases in the time dependence of surface climate boundary conditions. Based upon the relative deviations between respective nudged simulations in which these biases follow surface temperature from ice cores and eustatic sea level from marine sediment cores, we compute “ice core climate adjustments” that suggest how local paleoclimate observations may be applied to the systematic refinement of ICE‐6G_C. Our results are consistent with a growing body of evidence suggesting that the geographical origins of Meltwater Pulse 1B (MWP1b) may lie primarily in North America as opposed to Antarctica (as reconstructed in ICE‐6G_C).
基础水文学在劳伦泰德冰盖涌动中的作用
DOI：
10.5194/cp-2016-17
发表时间：
2016
期刊：
--
影响因子：
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作者：
Roberts W
通讯作者：
Roberts W