Advances in ice radar studies of a temperate alpine glacier, South Cascade Glacier, Washington, U.S.A.
Advances in ice radar studies of a temperate alpine glacier, South Cascade Glacier, Washington, U.S.A.
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美国华盛顿州南喀斯喀特冰川温带高山冰川的冰雷达研究进展
DOI：
10.3189/s0260305500012350
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发表时间：
1997
影响因子：
2.9
通讯作者：
R. Jacobel
中科院分区：
文献类型：
--
作者：
A. Fountain;R. Jacobel
美国华盛顿南喀斯喀特冰川，是西半球研究最广泛的冰川之一。除了1958年的质量平衡测量外，在过去三十年中还进行了许多水文调查，并使用各种技术反复测定冰厚。在1960年代后期，基底地形最初是通过重力测量方法确定的。20世纪70年代中期，人们首次利用雷达对温带冰层进行了深度测量。根据一系列点雷达测量和钻到冰川底部的钻孔，基础地形很快被重新绘制出来。在1990年代期间，利用连续剖面的数字记录重新绘制了冰厚图，获得了5000多个冰厚测量值。已针对天线辐射图的有限波束宽度和陡峭地形中的反射对剖面图进行了校正，从而大大改善了对基底表面和内部结构的描绘。根据我们最近的雷达剖面绘制的地图证实了先前描绘的基底地形的大尺度特征，并揭示了更多的结构细节。在冰川底部发现了一个明亮的反射体，可以在相邻的剖面中找到。与钻孔水位测量结果的比较表明，反射层是一个冰下管道。
South Cascade Glacier, Washington, U.S.A., is one of the most extensively studied glaciers in the Western Hemisphere. In addition to mass-balance measurements, which date to 1958, numerous hydrological investigations have been carried out during the last three decades, and repeated ice-thickness determinations have been made using a variety of techniques. In the late 1960s, the basal topography was initially determined by gravitimetric methods. In the mid-1970s some of the fist depth measurements using radar on temperate ice were made. The basal topography was remapped soon after from a series of point radar measurements and boreholes drilled to the glacier bottom. During the 1990s, the ice thickness was remapped using digital recording of continuous profiles that obtained over 5000 ice-thickness measurements. Profiles have been corrected for the finite beamwidth of the antenna radiation pattern and reflections in steep terrain, resulting in a significantly improved depiction of the basal surface and internal structures. The map based on our recent radar profiles confirms the large-scale features of the basal topography previously depicted and reveals more structural detail. A bright reflector was detected at the base of the glacier and could be traced in adjacent profiles. Comparison with results from water-level measurements in boreholes drilled to the bed indicates that the reflector is a subglacial conduit.