Ground-penetrating radar assisted ice core research : The challenge of Alpine glaciers and dielectric ice properties
Ground-penetrating radar assisted ice core research : The challenge of Alpine glaciers and dielectric ice properties
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探地雷达辅助冰芯研究：高山冰川和介电冰特性的挑战
DOI：
10.11588/heidok.00012800
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发表时间：
2011
影响因子：
5
通讯作者：
P. Bohleber
中科院分区：
文献类型：
--
作者：
P. Bohleber
阿尔卑斯山钻探现场的冰芯可能会提供长期的气候记录。然而，它们比极地的同行更难解释。本文研究了探地雷达对高山冰芯研究的辅助作用。首先，根据Colle Gnifetti(蒙特罗萨，4450米ASL)的多芯阵列，评估了稳定的水同位素记录重建大气信号的潜力。在这里，一个常见的大气信号是通过时间序列分析揭示的，尽管仍然需要对年龄-深度分布的足够知识才能正确解释。绘制同步的探地雷达反射图可以将冰芯的年代学始终如一地连接到现在之前的80年。通过简单的2.5维流动模型，这一时间延长到了120年，覆盖了整个钻探区域。根据冰芯的物理性质来解释探地雷达反射，关键依赖于复介电常数。为了专门研究这种材料特性，以前只受稀疏数据限制的无线电频率，一条适用于冰川的同轴传输线被改装。在-20°C下对1 MHz至1.5 GHz的纯冰、人造冰和天然冰的测量表明，各向同性冰的介电常数的实部为3.16+/-0.03。仅有的弥散迹象出现在10兆赫以下，这可能与德拜弥散的高频尾部有关。
Ice cores from Alpine drilling sites may provide long-term climate records. They are more complicated to interpret than their polar counterparts, however. The present thesis investigates the assistance for Alpine ice core research via ground-penetrating radar (GPR). First, the potential for reconstructing atmospheric signals is assessed for stable water isotope records based on a multi-core array at Colle Gnifetti (Monte Rosa, 4450 m asl). Here, a common atmospheric signal is revealed by time series analysis though adequate knowledge of the age-depth distribution is still needed for proper interpretation. Mapping isochronous GPR-reflections allows to consistently link the ice core chronologies up to 80 years before present. This is extended up to 120 years and over the whole drilling area by simple 2.5-dimensional flow modelling. Interpreting GPR-reflections in terms of physical ice core properties crucially relies on the complex dielectric permittivity. Aimed at investigating this material property specifically at radio-frequencies, previously constrained by sparse data only, a coaxial transmission line is adapted for glacier ice. Measurements of pure, artificial and natural ice samples between 1 MHz and 1.5 GHz at –20°C reveal for the permittivity of isotropic ice a real part of 3.16 +/- 0.03. The only signs of dispersion are found below 10 MHz, potentially associated with the high frequency tail of the Debye-dispersion.
DOI：
10.5194/tc-4-269-2010
发表时间：
2009-11
期刊：
The Cryosphere
影响因子：
--
作者：
U. Wollschläger;H. Gerhards;Qihao Yu;K. Roth
通讯作者：
U. Wollschläger;H. Gerhards;Qihao Yu;K. Roth