Polarization of radio waves transmitted through Antarctic ice shelves

Doake, C. S. M.; Corr, Hugh; Jenkins, Adrian

doi:10.3189/172756402781817572

Cited by 34 publications

(37 citation statements)

References 30 publications

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“…Data indicating correlations of birefringent effects with local ice flow are also not entirely concordant; at least one measurement found a lack of alignment between the implied birefringent basis and the surface ice flow direction (Doake, 1982;Woodruff and Doake, 1979).…”

Section: Birefringencementioning

confidence: 99%

“…www.the-cryosphere.net/7/855/2013/ (Fujita et al, 1996) Alaska single crystals (1.2 ± 0.2) % 9.7 GHz (Matsuoka et al, 1997) Alaska single crystals ∼ 1.1 % 1 MHz -39 GHz (Matsuoka et al, 1998) Dome Fuji core (0.33 ± 0.0.01)% 33 GHz (Doake et al, 2002) Brunt Ice Shelf (>0.14-0.47) % (Doake et al, 2003) George VI Ice Shelf (>0.05-0.15) % Mizuho measurable 60 MHz and 179 MHz (Fujita et al, 2006) Mizuho (0.5-1.2)% 60 MHz and 179 MHz (Besson et al, 2008) Taylor Dome 0.24 % time-domain (Kravchenko et al, 2010) South Pole 0.31 % time-domain Pulse generator output signal used for the primary measurements described herein. As seen in the figure, the total time delay through the associated cables has been measured to be 194 ns.…”

Section: Setupmentioning

confidence: 99%

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Radio-frequency probes of Antarctic ice at South Pole

Besson

Kravchenko

2013

The Cryosphere

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Abstract. Using hardware developed for the ARA (Askaryan Radio Array) particle astrophysics experiment, we herein report on the amplitude and temporal characteristics of polarized surface radar echo data collected in South Polar ice using radio sounding equipment with 0.5-ns echo-time sampling. We observe strong echoes at 6, 9.6, 13.9, 17, and 19 µs following vertical pulse emission from the surface, corresponding to reflectors in the upper half of the ice sheet. The synchronicity of those echoes for all broadcast azimuthal polarizations affirms the lack of observable birefringence over the upper half of the ice sheet. Of the five strongest echoes, three exhibit an evident amplitude correlation with the local surface ice flow direction, qualitatively consistent with measurements in East Antarctica. Combined with other radio echo sounding data, we conclude that observed birefringent asymmetries at South Pole are generated entirely in the lower half of the ice sheet. By contrast, birefringent asymmetries are observed at shallow depths in East Antarctica.

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Section: Birefringencementioning

confidence: 99%

Section: Setupmentioning

confidence: 99%

Radio-frequency probes of Antarctic ice at South Pole

Besson

Kravchenko

2013

The Cryosphere

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“…Multiple measurements at a variety of orientation angles and frequencies allow one to separate, to a large extent, the two contributions. Data collected on Brunt Ice Shelf near Halley Station resulted in an estimate of the minimum birefringent asymmetry in the effective permittivity (δ ǫ ′ ) of 0.14-0.52% [11], depending on location. The same experimental apparatus employed at George VI Ice Shelf yielded values typically 3× smaller.…”

Section: Fig 25mentioning

confidence: 99%

“…The response of ice as a function of polarization ("birefringence") has been probed with a variety of measurements [7,8,9,10,11,12]. Asymmetries are characterized as differences in either wavespeed or absorption along linear (generally orthogonal) axes.…”

Section: Introductionmentioning

confidence: 99%

In situ radioglaciological measurements near Taylor Dome, Antarctica and implications for ultra-high energy (UHE) neutrino astronomy

Besson

Jenkins

Matsuno

et al. 2008

Astroparticle Physics

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Radiowave detection of the Cherenkov radiation produced by neutrino-ice collisions requires an understanding of the radiofrequency (RF) response of cold polar ice. We herein report on a series of radioglaciological measurements performed approximately 10 km north of Taylor Dome Station, Antarctica from Dec. 6, 2006 -Dec. 16, 2006. Using RF signals broadcast from: a) an englacial discone, submerged to a depth of 100 meters and broadcasting to a surface dual-polarization horn receiver, and b) a dual-polarization horn antenna on the surface transmitting signals which reflect off the underlying bed and back up to the surface receiver, we have made time-domain estimates of both the real (index-of-refraction "n") and imaginary (attenuation length "Latten") components of the complex ice dielectric constant. We have also measured the uniformity of ice response along two orthogonal axes in the horizontal plane. We observe an apparent wavespeed asymmetry of order 0.1% between two orthogonal linear polarizations projected into the horizontal plane, consistent with some previous measurements, but somewhat lower than others.

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“…He developed a method for determining radar wave polarizations by rotating a pair of orthogonal receiving antennas and observing variations in echo strength, and presented a linear incremental trend in the phase difference between ordinary and extraordinary waves caused by the ice birefringence from field measurements in the vicinity of DYE-3 in Greenland. Thereafter, many researchers further investigated this subject (Woodruff and Doake, 1979;Doake, 1981;Doake et al, 2002;Fujita and Mae, 1994;Fujita et al, 1999Fujita et al, , 2006Matsuoka et al, 2003Matsuoka et al, , 2009Matsuoka et al, , 2012Drews et al, 2012). Woodruff and Doake (1979) suggested that large changes in the birefringence of ice sheets at the grounding zone were caused by the effect of tidal strain on crystal orientation.…”

Section: Introductionmentioning

confidence: 99%

Multi-channel and multi-polarization radar measurements around the NEEM site

González

Leuschen

et al. 2018

The Cryosphere

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Abstract. Ice properties inferred from multi-polarization measurements, such as birefringence and crystal orientation fabric (COF), can provide insight into ice strain, viscosity, and ice flow. In 2008, the Center for Remote Sensing of Ice Sheets (CReSIS) used a ground-based VHF (very high frequency) radar to take multi-channel and multi-polarization measurements around the NEEM (North Greenland Eemian Ice Drilling) site. The system operated with 30 MHz bandwidth at a center frequency of 150 MHz. This paper describes the radar system, antenna configurations, data collection, and processing and analysis of this data set. Within the framework derived from uniaxial ice crystal model, we found that ice birefringence dominates the power variation patterns of co-polarization and cross-polarization measurements in the area of 100 km 2 around the ice core site. The phase shift between ordinary and extraordinary waves increases nonlinearly with depth. The ice optic axis lies in planes that are close to the vertical plane and perpendicular or parallel to the ice divide depending on depth. The ice optic axis has an average tilt angle of about 11.6 • vertically, and its plane may rotate either clockwise or counterclockwise by about 10 • across the 100 km 2 area, and at a specific location the plane may rotate slightly counterclockwise as depth increases. Comparisons between the radar observations, simulations, and ice core fabric data are in very good agreement. We calculated the effective colatitude at different depths by using azimuth and colatitude measurements of the c axis of ice crystals. We obtained an average effective c axis tilt angle of 9.6 • from the vertical axis, very comparable to the average optic axis tilt angle estimated from radar polarization measurements. The comparisons give us confidence in applying this polarimetric radio echo sounding technique to infer profiles of ice fabric in locations where there are no ice core measurements.

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Polarization of radio waves transmitted through Antarctic ice shelves

Cited by 34 publications

References 30 publications

Radio-frequency probes of Antarctic ice at South Pole

Radio-frequency probes of Antarctic ice at South Pole

In situ radioglaciological measurements near Taylor Dome, Antarctica and implications for ultra-high energy (UHE) neutrino astronomy

Multi-channel and multi-polarization radar measurements around the NEEM site

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