Multichannel Wideband Synthetic Aperture Radar for Ice Sheet Remote Sensing: Development and the First Deployment in Antarctica

Wang, Zongbo; Gogineni, S.; Rodriguez‐Morales, Fernando; Yan, Jiahao; Paden, John; Leuschen, C.; Hale, Richard; Li, Jilu; Carabajal, Calen; Gómez-García, D.; Townley, Bryan; Willer, Robby; Stearns, L. A.; Child, Sarah F.; Braaten, D.

doi:10.1109/jstars.2015.2403611

Cited by 21 publications

(23 citation statements)

References 28 publications

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“…Given that the basal boundary is already identified as a major source of uncertainty in model projections 17 , 21 , they expose an urgent need to develop techniques for efficient measurement or more intelligent indirect estimation of short-wavelength subglacial topography beneath other vulnerable ice streams. One prospect for recovering short-wavelength subglacial topography may be provided by airborne swath–radar techniques that are currently under development 42 . Until such independent evaluation of form drag and basal friction is integrated into models, the current generation of ice-sheet models will be hampered in establishing projections of ice loss and sea-level rise.…”

Section: Discussionmentioning

confidence: 99%

Diverse landscapes beneath Pine Island Glacier influence ice flow

et al. 2017

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The retreating Pine Island Glacier (PIG), West Antarctica, presently contributes ~5–10% of global sea-level rise. PIG’s retreat rate has increased in recent decades with associated thinning migrating upstream into tributaries feeding the main glacier trunk. To project future change requires modelling that includes robust parameterisation of basal traction, the resistance to ice flow at the bed. However, most ice-sheet models estimate basal traction from satellite-derived surface velocity, without a priori knowledge of the key processes from which it is derived, namely friction at the ice-bed interface and form drag, and the resistance to ice flow that arises as ice deforms to negotiate bed topography. Here, we present high-resolution maps, acquired using ice-penetrating radar, of the bed topography across parts of PIG. Contrary to lower-resolution data currently used for ice-sheet models, these data show a contrasting topography across the ice-bed interface. We show that these diverse subglacial landscapes have an impact on ice flow, and present a challenge for modelling ice-sheet evolution and projecting global sea-level rise from ice-sheet loss.

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Section: Discussionmentioning

confidence: 99%

Diverse landscapes beneath Pine Island Glacier influence ice flow

et al. 2017

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“…Radar system, data acquisition, and processing The ultrawideband chirp radar, developed by the Center for Remote Sensing of Ice Sheets, was operated on AWI's Polar 6, a Basler BT-67 aircraft. The system hardware is an improved version of a previous design (37). It consists of three eight-element antenna arrays, operating in the frequency range of 150 to 520 MHz, with a 10-kHz pulse repetition frequency.…”

Section: Methodsmentioning

confidence: 99%

A large impact crater beneath Hiawatha Glacier in northwest Greenland

Kjær¹,

Larsen²,

Binder³

et al. 2019

ESPE

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We report the discovery of a large impact crater beneath Hiawatha Glacier in northwest Greenland. From airborne radar surveys, we identify a 31-kilometer-wide, circular bedrock depression beneath up to a kilometer of ice. This depression has an elevated rim that cross-cuts tributary subglacial channels and a subdued central uplift that appears to be actively eroding. From ground investigations of the deglaciated foreland, we identify overprinted structures within Precambrian bedrock along the ice margin that strike tangent to the subglacial rim. Glaciofluvial sediment from the largest river draining the crater contains shocked quartz and other impactrelated grains. Geochemical analysis of this sediment indicates that the impactor was a fractionated iron asteroid, which must have been more than a kilometer wide to produce the identified crater. Radiostratigraphy of the ice in the crater shows that the Holocene ice is continuous and conformable, but all deeper and older ice appears to be debris rich or heavily disturbed. The age of this impact crater is presently unknown, but from our geological and geophysical evidence, we conclude that it is unlikely to predate the Pleistocene inception of the Greenland Ice Sheet.

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“…The along-track and azimuth radiation patterns are not shown here because only the cross-track patterns are of primary interest to depth sounding applications (the effective along-track pattern is dominated by the SAR processing [5]). Further, because of the limitation on the available radiation distance, other far-field quantities, such as the gain and cross-polarization ratio, were not measured.…”

Section: Radiation Pattern Measurementmentioning

confidence: 99%

“…The proposed array is designed to operate with the upgraded version of the radar depth sounder described in [5]. The system is equipped with direct digital synthesizer (DDS) that generates LFM chirp waveforms from 150 to 550 MHz, with a typical pulse duration of 10 µs.…”

Section: Time-domain Performance Analysismentioning

confidence: 99%

“…Such radar would allow scientists to better estimate the basal conditions, as well as to sound the most challenging glaciers on Earth. In view of this, we have developed an ultrawideband radar depth sounder that operates over a frequency range of 150-450 MHz to measure ice shelves and fast-flowing glaciers [5]. Some of the major improvements being made to this radar are to further extend the upper frequency to 550 MHz and to raise the transmit power to 1 kW per channel.…”

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confidence: 99%

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A Polarization Reconfigurable Low-Profile Ultrawideband VHF/UHF Airborne Array for Fine-Resolution Sounding of Polar Ice Sheets

Yan

Hale

Mahmood

et al. 2015

IEEE Trans. Antennas Propagat.

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A polarization-reconfigurable low-profile ultrawideband VHF/UHF antenna array is presented in this paper. The design is based on resistively loaded planar dipole antenna elements backed with a ground plane. The antenna array has two mechanically field-switchable polarization configurations which are designed to measure the crystal orientation of ice sheets. The nominal operating mode of the array is in the vertically polarized configuration with operating frequency ranges from 150 to 550 MHz. The planar dimension of the array is 3.6 m × 0.8 m with a ground plane height of 16 cm (0.08λ low , flow = 150 MHz). Anechoic chamber measurements show that the array performance is in very good agreement with simulated results, for both VSWR and array radiation pattern. It is also shown that the array is capable of handling 1-kW peak power per transmit channel. The antenna array is housed within a flight-qualified composite S2-glass/epoxy fairing and can readily be mounted on airborne platforms, such as Basler BT-67 and Twin Otter, for radar sounding of polar ice sheets and glaciers.

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Multichannel Wideband Synthetic Aperture Radar for Ice Sheet Remote Sensing: Development and the First Deployment in Antarctica

Cited by 21 publications

References 28 publications

Diverse landscapes beneath Pine Island Glacier influence ice flow

Diverse landscapes beneath Pine Island Glacier influence ice flow

A large impact crater beneath Hiawatha Glacier in northwest Greenland

A Polarization Reconfigurable Low-Profile Ultrawideband VHF/UHF Airborne Array for Fine-Resolution Sounding of Polar Ice Sheets

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