Alaska tidewater glacier terminus positions, 1948-2012
Alaska tidewater glacier terminus positions, 1948-2012
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DOI：
10.1002/2013jf002915
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发表时间：
2014-02-01
影响因子：
3.9
通讯作者：
Hock, R.
中科院分区：
文献类型：
--
作者：
McNabb, R. W.;Hock, R.
世界上很大一部分的冰川冰通过冰川出口流出，尽管关于冰川对最近气候变化的反应仍然未知。我们提出了一个64年的记录长度变化的50阿拉斯加冰川。我们使用美国地质调查局的地形图来提供1970年之前冰川的基准长度。使用所有可用的无云Landsat图像，我们手动绘制了1972年至2012年期间每个冰川的崩解锋轮廓，总共产生了10，000多个轮廓。潮汐冰川长度随季节变化，专注于36个冰川终止在tillage在整个研究期间，我们发现一个平均值（标准差）的季节变化为60 - 85米（-1）。我们使用这些振荡来确定冰川长度年际变化的意义。所有36个冰川都经历了至少一个时期（1年）的显著前进或退缩; 28个冰川经历了至少一个时期的显著前进和退缩。在整个1948-2012年期间，这些冰川中有24个退缩了107.950.29公里（不确定性），11个前进了7.71 +/- 0.20公里，一个（Chenega冰川）没有显着变化。退缩和前进在时间上变化很大;几个冰川经历了几年的快速短期退缩。这些撤退发生在夏季海表温度异常的巨大变化之后;需要进一步研究以确定是什么引发了这些撤退。尽管两个次区域表现出与格陵兰岛最近观察到的相似的一致性，但在长度记录中没有明显的区域行为信号。
A significant portion of the world's glacier ice drains through tidewater outlets, though much remains unknown about the response to recent climate change of tidewater glaciers. We present a 64 year record of length change for 50 Alaska tidewater glaciers. We use U.S. Geological Survey topographic maps to provide a base length for glaciers before 1970. Using all available cloud-free Landsat images, we manually digitize calving front outlines for each glacier between 1972 and 2012, resulting in a total of more than 10,000 outlines. Tidewater glacier lengths vary seasonally; focusing on the 36 glaciers terminating in tidewater throughout the study period, we find a mean ( standard deviation) seasonal variation of 60 85m a(-1). We use these oscillations to determine the significance of interannual changes in glacier length. All 36 glaciers underwent at least one period (1 year) of significant advance or retreat; 28 glaciers underwent at least one period of both significant advance and retreat. Over the entire period 1948-2012, 24 of these glaciers retreated a total ( uncertainty) of 107.950.29 km, 11 advanced a total of 7.71 +/- 0.20, and one (Chenega Glacier) did not change significantly. Retreats and advances are highly variable in time; several glaciers underwent rapid, short-term retreats of a few years duration. These retreats occurred after large changes in summer sea surface temperature anomalies; further study is needed to determine what triggered these retreats. No coherent regional behavior signal is apparent in the length record, although two subregions show a coherence similar to recent observations in Greenland.