HR: 16:45h
AN: NS14A-04 INVITED    [Abstracts]
TI: Laboratory and numerical experiments of radar back scattering: towards interpreting the shape of subsurface targets in cryospheric applications
AU: * Matsuoka, K
EM: matsuoka@ess.washington.edu
AF: Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Marshall, H
EM: marshalh@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado at Boulder, Campus Box 450, Boulder, CO 80309, United States
AB: Subsurface radar remote sensing is a powerful tool for examining the top 10⁰-10¹ m of soil and seasonal snow, and 10²-10³ m of glacier ice. High frequency radar has high resolution, but poor penetration, while the opposite is true for low frequency radar. If targets are in lossy media (e.g. temperate ice, wet snow, and wet soil), only low frequency radar is usable but visualization of individual targets is unfeasible. We have tested an idea that echo-intensity variations in terms of radar polarization and frequency can constrain the shape and dimensions of targets. Scattering amplitude and its directional pattern are a function of refraction index of the target, relative to the medium, and dimensions of the target, relative to the wavelength in the medium. By changing the relative wavelength and refraction index, we can perform experiments that are practical in the laboratory, and use the findings to make inferences at larger scales and in different media. We measured microwave (2-18 GHz) radar backscatter of small targets in open-air in the laboratory, giving us accurate control and knowledge of target orientation, size and shape, as well as refractive index. Computer simulations were made with the Discrete Dipole Approximation model. This approximation allows larger target dimensions and higher refraction indecies than other computing methods. In this talk, we first review a range of targets of interest in the cryosphere, and then present several examples of laboratory experiments and computer simulations designed to simulate these conditions.
DE: 0710 Periglacial processes
DE: 0720 Glaciers
DE: 0794 Instruments and techniques
SC: Near-Surface Geophysics [NS]
MN: 2007 Fall Meeting