Reconstruction of mass balance of glaciers in southern Norway back to 1948
Reconstruction of mass balance of glaciers in southern Norway back to 1948
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DOI：
10.3189/172756407782871242
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发表时间：
2007-10
影响因子：
2.9
通讯作者：
L. A. Rasmussen;L. Andreassen;H. Conway
中科院分区：
文献类型：
--
作者：
L. A. Rasmussen;L. Andreassen;H. Conway
摘要 使用美国国家环境预测中心和美国国家大气研究中心 (NCEP/NCAR) 再分析数据库中的高空气象变量的模型，将挪威南部七个冰川的净平衡值延长至 1948 年。另一个冰川 Storbreen 的观测记录始于 1948 年。在七个冰川的观测记录中，Storbreen 的相关性对其中四个冰川的估计比高空模型更准确，而对三个冰川的估计则不太准确。然而，在所有七种情况下，模型和 Storbreen 相关性的平均值比单独使用其中任何一个都更准确，因此在未观察到的情况下，多年来均使用平均值来重建 b n 。对于 Storbreen 以外的七个冰川，一个组合系列是根据其记录期间的观测和 1948 年之前的重建值形成的。所有八个 b n 系列中有三个不同的部分：1989 年之前；1989 年之前；1989 年之前；1989 年之前；1989 年之前；1989 年之前； 1989-1995年，北大西洋涛动指数呈强正值； 1995 年以后。1989-95 年平均 b n 异常为正，因为消融减少，尤其是积累增加。由于消融增加，自 1995 年以来的平均 b n 一直异常为负，而累积量几乎与 1948-88 年相同。 1949-2005 年八个系列的第一个主成分解释了总方差的 78%，第二个主成分解释了 12%。 1949-88 年期间，1948 年之后开始观测的七个冰川的 b n 或冬季平衡 b w 或夏季平衡 b s 都没有发生重大变化，Storbreen 记录中也没有发生重大变化。 1948 年至 2005 年间质量增加的三座冰川和质量减少的五座冰川之间存在区别。获胜的 3 个，其海拔范围最低十分之一的积聚面积比 AAR ≥ 0.64，且 < 其面积 δS 的 0.7%，而失败的 5 个，AAR ≤ 0.46，1.9 ≤ δS ≤ 4.4%。由于这些高度测量，失去质量的五个冰川现在有一个特别大的消融区域。
Abstract A model using upper-air meteorological variables in the US National Centers for Environmental Prediction and US National Center for Atmospheric Research (NCEP/NCAR) re-analysis database is used to extend net balance b n back to 1948 for seven glaciers in southern Norway. The observational record of another glacier, Storbreen, began in 1948. Over the observational record of each of the seven glaciers, correlation with Storbreen estimates b n more accurately than the upper-air model does for four of them and less accurately for three. In all seven cases, however, an average of the model and the Storbreen correlation is more accurate than either alone, so the average is used to reconstruct b n for years when it was not observed. For the seven glaciers other than Storbreen, a combined series is formed from observations during their period of record and from reconstructed values prior to then back to 1948. There are three distinct sections in all eight b n series: prior to 1989; 1989–1995, when the North Atlantic Oscillation index was strongly positive; and after 1995. The 1989–95 mean b n was anomalously positive because of both decreased ablation and especially increased accumulation. The mean b n since 1995 has been anomalously negative because of increased ablation, whilst accumulation has been nearly the same as over 1948–88. The first principal component of the eight 1949–2005 b n series explains 78% of the total variance, and the second explains 12%. Over 1949–88 there were no substantial shifts in b n or in either winter balance b w or summer balance b s at any of the seven glaciers where observations began after 1948, nor were there in the Storbreen record. There is a distinction between the three glaciers that gained mass over 1948–2005 and the five that lost mass. Each of the three that gained had accumulation-area ratio AAR ≥ 0.64 and <0.7% of its area δS in the lowest tenth of its altitude range, while the five that lost had AAR ≤ 0.46 and 1.9 ≤ δS ≤ 4.4%. Because of these hypsometries, the five glaciers that lost mass now have an especially large ablation area.