Radio-echo layering in polar ice sheets and past volcanic activity
Radio-echo layering in polar ice sheets and past volcanic activity
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DOI：
10.1038/292441a0
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发表时间：
1981-07
期刊：
影响因子：
64.8
通讯作者：
D. H. M. Millar
中科院分区：
文献类型：
--
作者：
D. H. M. Millar
最近的一项研究表明，格陵兰冰芯沿线的酸度曲线可以揭示北半球在过去10,000年间的大规模火山喷发。有人提出，极地冰盖中的这些酸性冰层也可以通过航空无线电回波探测(RES)技术探测到，即分层回波2-4。火山爆发将大量二氧化硫喷射到平流层5，在那里形成硫酸气溶胶6。对南极雪盖7和格陵兰冰芯2的研究表明，这种物质可以在极地冰盖上大面积沉积。根据对这些弱酸性层的观测进行的计算表明，它们应该会引起与层结回波观测到的类似级别的雷达反射。来自南极的新的RES数据使目前的比较可以在观测到的层功率反射系数(PRCs)与酸性冰层和密度变化的冰层的反射值之间进行。已经确定了一个分层的缺口，这似乎与格陵兰岛在Créte8报道的一个类似的缺口相吻合；PRC层随年龄的变化显示出南极冰盖上许多地点的共同模式。这一PRC/年龄剖面可能提供了过去150,000年来南半球火山爆发活动的记录。
A recent study1has shown how acidity profiles along dated Greenland ice cores can reveal large volcanic eruptions in the Northern Hemisphere during the past 10,000 yr. It has been suggested that these layers of acidic ice in the polar ice sheets may also be detected by airborne radio-echo sounding (RES) techniques as stratification echoes2–4. Explosive volcanic eruptions eject large amounts of SO2into the stratosphere5where it forms an H2SO4aerosol6. Studies of Antarctic snow7and Greenland ice cores2show that this material can be deposited in layers of large areal extent on polar ice sheets. Calculations based on observations of these slightly acidic layers show that they should give rise to radar reflections of similar magnitude to those observed for stratification echoes. New RES data from the Antarctic enables the present comparison to be made between observed layer power reflection coefficients (PRCs), and calculated values for reflections from acidic ice layers and from layers of ice of changed density. A gap in layering has been identified which seems to coincide with a similar gap reported in Greenland at Crête8; profiles of layer PRC against age show a common pattern for many sites on the Antarctic ice sheet. This PRC/age profile may provide a record of explosive volcanic activity for the Southern Hemisphere over the past 150,000 yr.