Modeling of anisotropic electromagnetic reflection from sea ice, Rep
The contribution of brine layers to observed reflective anisotropy of sea ice at 100 MHz is quan-titatively assessed, and a theoretical explanation for observed reflective anisotropy is proposed in terms of anisotropic electric flux penetration into the brine layers. The sea ice is assumed to be a s...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Published: |
1980
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| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.488.3777 http://www.math.utah.edu/~golden/mypapers/Golden_Ackley_JGR_1981.pdf |
| Summary: | The contribution of brine layers to observed reflective anisotropy of sea ice at 100 MHz is quan-titatively assessed, and a theoretical explanation for observed reflective anisotropy is proposed in terms of anisotropic electric flux penetration into the brine layers. The sea ice is assumed to be a stratified dielec-tric consisting of pure ice containing ellipsoidal conducting inclusions (brine layers) uniformly aligned with their long axes perpendicular to the preferred crystallographic axis direction. The asymmetrical geometry of the brine layers is shown to produce an anisotropy in the complex dielectric constant of sea ice. The contribution of these layers to the reflective anisotropy is examined with a numerical method of approximating the reflected power of a radar pulse incident on a slab of sea ice. Mixture dielectric per-mittivities are calculated for both the electric fields parallel and perpendicular to the c axis direction. These permittivities are then used to calculate power reflection coefficients at each interface in the air/sea ice/sea water system. Significant bottom reflection (R = 0.09) occurs when the polarization is parallel to the c axis. However, when the polarization is perpendicular to the c axis, the return is almost completely extinguished (R < 0.003). This extinction is due primarily to absorptive loss associated with the con-ducting inclusions and secondarily to an impedance match at the ice/water interface that results in trans-mission rather than reflection of the wave. |
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