Local to regional‐scale variability of annual net accumulation on the Greenland ice sheet from PARCA cores
Local to regional‐scale variability of annual net accumulation on the Greenland ice sheet from PARCA cores
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DOI：
10.1029/2001jd900067
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发表时间：
2001-12
影响因子：
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通讯作者：
E. Mosley‐Thompson;J. McConnell;R. Bales;Z. Li;P. Lin;K. Steffen;L. Thompson;R. Edwards;D. Bathke
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文献类型：
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作者：
E. Mosley‐Thompson;J. McConnell;R. Bales;Z. Li;P. Lin;K. Steffen;L. Thompson;R. Edwards;D. Bathke
在北极区域气候评估计划（PARCA）下收集的一套空间分布的岩芯提供了前所未有的机会来评估格陵兰冰盖年积累率的局部到区域的变化。 PARCA 核心的独特之处在于其广泛的空间分布和使用多个季节性变化指标对年层进行准确测年的能力。核心数据提供（1）对积累率的空间和时间变化进行更严格的评估，（2）冰盖质量平衡估计的关键输入，（3）卫星观测的地面实况测量和基于气候模型的降水估计，以及（4）对冰芯古气候解释的重要约束。多个紧密间隔的岩心表明，冰盖中保存的高频（年度至可能十年尺度）气候变化信号部分被冰川噪声掩盖。两处 350 年的堆积历史，一处来自格陵兰岛西北部，另一处来自山顶地区，揭示了显着的数十年变化。区域趋势显示出长期（60-90年）的强正相关和同样长的强负相关。自 1940 年以来，趋势已经脱钩。这种空间变化反映了北大西洋大气环流模式的变化对格陵兰降水（及其包含的气候信息）的强烈调节。 PARCA 核心的代理记录表明，必须谨慎解释单个核心的气候重建，并应用适当的滤波器来减少局部噪声，并从局部到区域尺度进行仔细的推断。更丰富、更强大的冰芯数据集应该通过组合多个、间隔更广泛的冰芯来产生区域堆积记录。
A suite of spatially distributed cores collected under the Program for Arctic Regional Climate Assessment (PARCA) provides an unprecedented opportunity to assess local to regional variability of annual accumulation rates over the Greenland ice sheet. PARCA cores are unique in their broad spatial distribution and accurate dating of annual layers using multiple seasonally varying indicators. The core data provide (1) a more rigorous evaluation of spatial and temporal variations in accumulation rates, (2) critical input to ice sheet mass balance estimates, (3) ground truth measurements for satellite observations and climate model-based precipitation estimates, and (4) important constraints on paleoclimatic interpretations from ice cores. Multiple closely spaced cores demonstrate that signals of high-frequency (annual to possibly decadal scale) climate variability preserved in the ice sheet are partially masked by glaciological noise. Two 350-year accumulation histories, one from northwest Greenland and one from the summit area, reveal significant multidecadal variability. The regional trends show long periods (60–90 years) of strong positive correlation and an equally long period of strong negative correlation. Since 1940 the trends have been decoupled. This spatial variability reflects the strong modulation of Greenland precipitation (and the climate information it contains) by changes in North Atlantic atmospheric circulation patterns. Proxy records from the PARCA cores document that climate reconstructions from a single core must be interpreted cautiously, with application of appropriate filters to reduce local noise and careful extrapolations from local to regional scales. Richer, more robust ice core-derived data sets should result from combining multiple, more widely spaced cores to produce regional stacked records.