Radar reflections reveal a wet bed beneath stagnant Ice Stream C and a frozen bed beneath ridge BC, West Antarctica
Radar reflections reveal a wet bed beneath stagnant Ice Stream C and a frozen bed beneath ridge BC, West Antarctica
复制标题
雷达反射揭示了南极洲西部停滞冰流 C 下方的湿床和 BC 山脊下方的冰床
作者：
C. Bentley;N. Lord;C. Liu
在1987-1988年南极野外考察期间，收集了9个网格区块的数字机载雷达数据，覆盖了冰流B(间距6公里)和冰流C(间距11公里)的下游部分，以及它们之间的一部分海脊BC。自动处理程序用于拾取反射雷达脉冲的起始时间、将旅行时间转换为距离、对缺失数据进行内插、转换压力传感器读数、校正导航漂移、执行交叉分析以及将剩余交叉误差归零。采用最小曲率法进行线段间插补。绘制了冰层厚度(估计精度20米)和基本反射强度(估计精度1分贝)的地图。冰层厚度图确认了以前侦察图的特征，没有显示新的特征。反射强度图显示了冰流和卑诗省海脊之间以及这两个冰流本身之间的明显对比。我们将反射强度解释为C冰流和B冰流的床都是未冻结的，BC脊的床是冻结的，BC脊的冻结层和C冰流的非冻结层之间的边界正好位于冰流以前的切变边缘之下。
Abstract Digital airborne radar data were collected during the 1987-88 Antarctic field season in nine gridded blocks covering the downstream portions of Ice Stream B (6km spacing) and Ice Stream C (11 km spacing), together with a portion of ridge BC between them. An automated processing procedure was used for picking onset times of the reflected radar pulses, converting travel times to distances, interpolating missing data, converting pressure transducer readings, correcting navigational drift, performing crossover analysis, and zeroing rémanent crossover errors. Interpolation between flight-lines was carried out using the minimum curvature method. Maps of ice thickness (estimated accuracy 20 m) and basal-reflection strength (estimated accuracy 1 dB) were produced. The ice-thickness map confirms the characteristics of previous reconnaissance maps and reveals no new features. The reflection-strength map shows pronounced contrasts between the ice streams and ridge BC and between the two ice streams themselves. We interpret the reflection strengths to mean that the bed of Ice Stream C, as well as that of Ice Stream B, is unfrozen, that the bed of ridge BC is frozen and that the boundary between the frozen bed of ridge BC and the unfrozen bed of Ice Stream C lies precisely below the former shear margin of the ice stream.