SPATIAL AND TEMPORAL VARIABILITY OF NET ACCUMULATION FROM SHALLOW CORES FROM VESTFONNA ICE CAP (NORDAUSTLANDET, SVALBARD)
SPATIAL AND TEMPORAL VARIABILITY OF NET ACCUMULATION FROM SHALLOW CORES FROM VESTFONNA ICE CAP (NORDAUSTLANDET, SVALBARD)
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DOI：
10.1111/j.1468-0459.2011.00439.x
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发表时间：
2011-12-01
影响因子：
1.5
通讯作者：
Moore, John C.
中科院分区：
文献类型：
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作者：
Beaudon, Emilie;Arppe, Laura;Moore, John C.
我们分析冰芯从Vestfonna冰帽（Nordustlandet，斯瓦尔巴群岛）。氧同位素测量的三个雪芯（6.0，11.0和15.5米深）从两个最高峰的冰川位于西南偏东和西北偏东的中央山脊。亚年度d18 O周期被保存，可以计算直观的核心的最高部分，但更深的层沉积后平滑的影响。一个明显的d18 O最低被发现附近的三个核心的底部。我们认为这个d18 O信号的候选者是一个有价值的参考地平线，因为它也可以在Nordustlandet的其他地方看到。我们将其归因于同位素耗尽的雪降水，NCEP/NCAR再分析表明，这是不寻常的Vestfonna，来自偏北空气在寒冷的冬季1994/95。找到1994/95年的时间标记，可以为三个岩心建立精确的深度/年龄表。推导出的年累积率间接填补了物质平衡测量的地理空白，从而提供了冰川上的降水的空间和时间变化的核心跨越的时期（1992 - 2009年）的信息。比较这两个地点的记录还发现，过去17年来，韦斯特丰纳最东部的雪网累积量仅为西部的一半。
We analyse ice cores from Vestfonna ice cap (Nordaustlandet, Svalbard). Oxygen isotopic measurements were made on three firn cores (6.0, 11.0 and 15.5 m deep) from the two highest summits of the glacier located on the SWNE and NWSE central ridges. Sub-annual d18O cycles were preserved and could be counted visually in the uppermost parts of the cores, but deeper layers were affected by post-depositional smoothing. A pronounced d18O minimum was found near the bottom of the three cores. We consider candidates for this d18O signal to be a valuable reference horizon since it is also seen elsewhere in Nordaustlandet. We attribute it to isotopically depleted snow precipitation, which NCEP/NCAR reanalysis shows was unusual for Vestfonna, and came from northerly air during the cold winter of 1994/95. Finding the 1994/95 time marker allows establishment of a precise depth/age scale for the three cores. The derived annual accumulation rates indirectly fill a geographical gap in mass balance measurements and thus provide information on spatial and temporal variability of precipitation over the glacier for the period spanned by the cores (19922009). Comparing records at the two locations also reveals that the snow net accumulation at the easternmost part of Vestfonna was only half of that in the western part over the last 17 years.