Polarimetric ice sounding at P-band: First results

Abstract

For polar ice sheets valuable stress and strain information can be deduced from the crystal orientation fabric (COF) and its prevailing c-axis alignment. Polarimetric radio echo sounding is a promising technique to measure the anisotropic electromagnetic propagation and reflection properties associated with the COF. In this paper, dualpolarized P-band data acquired with the airborne POLARIS system near the ice divide of the Greenland ice sheet are analyzed. The internal layers in the uppermost few hundred meters of the ice sheet look the same at HH and VV polarizations, whereas the layering differs further down. Accordingly, the magnitude of the complex HH-VV correlation coefficient decreases with depth and, interestingly, the phase gives evidence of polarization dependent reflection and birefringence effects.

Ice sheet anisotropy measured with polarimetric ice sounding radar

“…The magnitude of this coherence is a measure of the similarity of the HH and VV data. At the southern test site the HHVV coherence magnitude is almost unity down to some 200 m, under which it drops to about 0.3 [7]. Figure 2 shows the HHVV coherence phase for a shallow sounding at the southern test site.…”

“…First results from the PoC campaign have already been presented [7], and in this paper these date are interpreted in terms of a simple electromagnetic model accounting for both propagation and reflection processes. Also, while the PoC data are confined to a maximum depth of about 1 km, the ATC data cover the entire ice sheet from the surface to the bedrock.…”

Strain history of ice shells of the Galilean satellites from radar detection of crystal orientation fabric

“…Anisotropic reflectivity and birefringence vary periodically with polarization angle [ Hargreaves , 1977; Matsuoka et al , 2003]. Zones of anisotropic reflectivity and birefringence have been detected by comparing the received power of dual co‐polarization (i.e., linear polarization parallel and perpendicular to the ground track) ice‐penetrating radar data [ Matsuoka et al , 2003; Dall , 2009, 2010]. Polarization‐dependent reflectivity provides an unambiguous means of detecting COF and could be used to test hypotheses about ice shell heat transfer and modes of resurfacing.…”

“…[4] On Earth, COF detected by seismic [Blankenship, 1989] and radar sounding [Siegert and Kwok, 2000;Siegert and Fujita, 2001;Matsuoka et al, 2003;Dall, 2009Dall, , 2010 has been used to infer the strain history of ice sheets. For single-crystal and polycrystalline ice with well-developed COF (" ) 1 at high temperature), the difference between the real part of the dielectric permittivity , in a direction parallel to ( k ) and perpendicular to ( ? )…”

“…On Earth, COF detected by seismic [ Blankenship , 1989] and radar sounding [ Siegert and Kwok , 2000; Siegert and Fujita , 2001; Matsuoka et al , 2003; Dall , 2009, 2010] has been used to infer the strain history of ice sheets. For single‐crystal and polycrystalline ice with well‐developed COF (ɛ ≫ 1 at high temperature), the difference between the real part of the dielectric permittivity ε, in a direction parallel to (ε ∥ ) and perpendicular to (ε ⊥ ) the c ‐axis is about 1% [ Johari and Charette , 1975; Fujita et al , 1993], which causes radar reflections at abrupt contrasts in COF, anisotropic reflectivity, and birefringence [ Matsuoka et al , 2003].…”