Surface mass balance, thinning and iceberg production, Columbia Glacier, Alaska, 1948–2007
Surface mass balance, thinning and iceberg production, Columbia Glacier, Alaska, 1948–2007
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DOI：
10.3189/002214311796905532
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发表时间：
2011-08
影响因子：
3.4
通讯作者：
L. A. Rasmussen;H. Conway;R. Krimmel;R. Hock
中科院分区：
文献类型：
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作者：
L. A. Rasmussen;H. Conway;R. Krimmel;R. Hock
以高空气象资料为输入的物质平衡模式是以1977-78年在阿拉斯加哥伦比亚冰川上135-2645ma.s.l之间的67个测点的地面物质平衡为主要测量数据进行校准的。模型与实测值的均方根误差为1.0mW.E.A−1，r2=0.88。分析的一个显著结果是，降雨量和用于估算地表烧蚀的正度日模型中的因子都随海拔变化而恒定。该模型被应用于重建1948-2007年间冰川范围内的地表物质平衡分量。表面烧蚀，4千米冰当量。−1(冰当量)，在整个时期几乎没有变化。从1948年到1981年左右开始急剧退缩，表面物质平衡为正，但冰川几何形状的变化很小，因此正平衡被崩解所抵消，∼为0.9km~3冰当量。A−1。在退缩过程中，冰川体积损失占冰山产量的92%。产奶量增加到∼4.3km3冰当量。从1982年到1995年的−1，并在此之后的2007年到∼8.0千米冰当量。−1，大约是表面消融损失的两倍，而在撤退之前，它只有大约四分之一的损失。冰川崩解是指整个冰川表面质量平衡与大地测量确定的体积变化之间的差值。
Abstract A mass-balance model using upper-air meteorological data for input was calibrated with surface mass balance measured mainly during 1977–78 at 67 sites on Columbia Glacier, Alaska, between 135 and 2645 m a.s.l. Root-mean-square error, model vs measured, is 1.0 m w.e. a−1, with r 2 = 0.88. A remarkable result of the analysis was that both precipitation and the factor in the positive degree-day model used to estimate surface ablation were constant with altitude. The model was applied to reconstruct glacier-wide components of surface mass balance over 1948–2007. Surface ablation, 4 km3 ice eq. a−1 (ice equivalent), has changed little throughout the period. From 1948 until about 1981, when drastic retreat began, the surface mass balance was positive but changes in glacier geometry were small, so the positive balance was offset by calving, ∼0.9 km3 ice eq. a−1 . During retreat, volume loss of the glacier accounted for 92% of the iceberg production. Calving increased to ∼4.3 km3 ice eq. a−1 from 1982 to 1995, and after that until 2007 to ∼8.0 km3 ice eq. a−1, which was about twice the loss by surface ablation, whereas prior to retreat it was only about a quarter as much. Calving is calculated as the difference between glacier-wide surface mass balance and geodetically determined volume change.