Inferring the variation of climatic and glaciological contributions to West Greenland iceberg discharge in the twentieth century
Inferring the variation of climatic and glaciological contributions to West Greenland iceberg discharge in the twentieth century
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DOI：
10.1016/j.coldregions.2015.08.006
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发表时间：
2016
影响因子：
4.1
通讯作者：
Yifan Zhao;G. Bigg;S. Billings;Edward Hanna;A. Sole;Hua-Liang Wei;V. Kadirkamanathan;D. Wilton
中科院分区：
文献类型：
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作者：
Yifan Zhao;G. Bigg;S. Billings;Edward Hanna;A. Sole;Hua-Liang Wei;V. Kadirkamanathan;D. Wilton
冰山排放是格陵兰冰盖物质平衡的主要组成部分。虽然已经存在对流量随时间变化的整体估计，从对接地线冰速的测量或表面质量平衡计算中遥远地推断出来，但直到最近几年，才有关于个别海洋终端冰川流量本身的详细测量。最近，通过海洋-冰山模拟和非线性系统识别相结合的方法表明，西大西洋冰山数量超过北纬48度的长达一个世纪的记录是至少从格陵兰南部和西部排放的一个很好的一级指标。在这里，我们通过对48oN时间序列的非线性自回归数学模型的敏感性研究，来探索20世纪这些地区冰山排放的冰盖、海洋和气候强迫的相对重要性的变化。我们发现，这种关系主要是非线性的，在本世纪上半叶，GRIS表面质量平衡对冰山排放的贡献可能占主导地位。在这一时期之后的几十年里，海洋温度效应在决定冰山排放的模型变化方面起着最重要的作用。近几十年来，所有物理过程在解释冰山排放方面都发挥了不可忽视的作用，该模型表明，冰川对环境变化的响应时间可能已经缩短。
Iceberg discharge is a major component of the mass balance of the Greenland Ice Sheet (GrIS). While bulk estimates of discharge variation over time exist, inferred remotely from measurements of grounding line ice velocities or surface mass balance calculations, few detailed measurements of discharge itself from individual marine-terminating glaciers existed until recent years. Recently, it has been shown, through a combination of ocean–iceberg modelling and non-linear system identification, that the century-long record of iceberg numbers crossing 48oN in the West Atlantic is a good first-order proxy for discharge from at least south and west Greenland. Here, we explore the varying relative importance of ice sheet, oceanic and climatic forcing of iceberg discharge from these areas over the twentieth century, by carrying out sensitivity studies of a non-linear auto-regressive mathematical model of the 48oN time series. We find that the relationships are mainly non-linear, with the contribution of the GrIS surface mass balance to iceberg discharge likely to be dominant in the first half of the century. This period is followed by several decades where oceanic temperature effects are most important in determining the model variation in iceberg discharge. In recent decades, all physical processes play a non-negligible part in explaining the iceberg discharge and the model suggests that the glacial response time to environmental changes may have decreased.