The Study of the COF Feature in the Antarctic Ice Sheet Based on 3‐D Anisotropy FDTD Method
The Study of the COF Feature in the Antarctic Ice Sheet Based on 3‐D Anisotropy FDTD Method
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DOI：
10.1002/cjg2.1361
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发表时间：
2009-03
期刊：
影响因子：
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通讯作者：
Bangbing Wang;G. Tian;Bo Sun;X. Cui
中科院分区：
文献类型：
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作者：
Bangbing Wang;G. Tian;Bo Sun;X. Cui
RES技术的应用是研究南极冰盖内部结构最重要的方法。近年来发展起来的多极化雷达方法可以根据反射功率在不同方向上的变化推断出冰盖中COF的特征和变化规律，进而确定冰盖内的应力和形变历史。了解冰盖的流动机制和动力过程，解释冰盖过去、现在和未来的变化规律具有重要意义。本文从麦克斯韦方程出发，推导出适用于介电常数各向异性介质的三维时域有限差分方程。然后模拟了响应和时空分布特征。仿真结果表明，雷达波在各向异性介质中传播时，波前为椭球体，其长轴位于最小介电常数轴上。在横向各向异性介质中传播的反射波振幅在水平面上具有180°周期。从各向异性层底部开始，不同天线类型之间的时延和周期幅度变化，时延和周期幅度变化与各向异性层之间和相邻层之间的介电常数差有关。然后讨论了介电常数各向异性引起延时和周期性振幅变化的原因。研究结果和结论有助于指导南极RES勘探资料的处理和解释。
The application of RES technology is the most important method for the study of inner structure on the Antarctic ice sheet. The multi-polarization radar method developed in recent years can deduce the feature and changing rule of COF in the ice sheet according to the variation of the reflecting power in different orientations, and determine the history of stain and stress in the ice sheet further. It is important to understand the flow mechanism and dynamic process and explain the changing law of the ice sheet in the past, present and future. In this paper we deduced the 3-D FDTD equations which were derived from Maxwell equation and adapted to permittivity anisotropy medium. Then we simulate the response and spatial-temporal distributing features. The simulating results show that the wave front is ellipsoid and its long axis lies on the axis of minimum permittivity while the radar wave propagating in the anisotropy medium. The amplitude of the reflecting wave propagating in the traverse anisotropy medium has an 180° period in the horizon plane. We find the delay and periodical amplitude variations from the bottom of anisotropy layer between different antenna types, and the delay and periodical amplitude variation is related to the permittivity difference between the different directions of anisotropy layers and between the adjacent layers. Then we discuss the reason for the delay and periodical amplitude variation because of permittivity anisotropy. The results and conclusions can help to instruct the data processing and interpretation from the Antarctic RES exploration.