文章基本信息

标题：Surface mass balance, thinning and iceberg production, Columbia Glacier, Alaska, 1948–2007
本地全文：下载
作者：L.A. Rasmussen ; H. Conway ; R.M. Krimmel 等
期刊名称：Journal of Glaciology
印刷版ISSN：0022-1430
电子版ISSN：1727-5652
出版年度：2011
卷号：57
期号：203
页码：431-440
DOI：10.3189/002214311796905532
出版社：Cambridge University Press
摘要：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 km 3 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 km 3 ice eq. a −1 . During retreat, volume loss of the glacier accounted for 92% of the iceberg production. Calving increased to ∼4.3 km 3 ice eq. a −1 from 1982 to 1995, and after that until 2007 to ∼8.0 km 3 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.