SAR processing of radar echo sounder data

Leuschen, C.; Gogineni, S.; Tammana, D.

doi:10.1109/igarss.2000.859643

Cited by 20 publications

(16 citation statements)

References 4 publications

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“…This output is used to automatically determine the ice surface location by using a maximum power layer tracker. CReSIS SAR processing algorithms use the surface location to model the ice as a layered media for fk migration (Leuschen and others, 2000). A simple dielectric half-space is used for representing the layered media with a relative dielectric permittivity of ice of 3.15.…”

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confidence: 99%

Bed topography and subglacial landforms in the onset region of the Northeast Greenland Ice Stream

et al. 2020

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The Northeast Greenland Ice Stream (NEGIS) is an important dynamic component for the total mass balance of the Greenland ice sheet, as it reaches up to the central divide and drains 12% of the ice sheet. The geometric boundary conditions and in particular the nature of the subglacial bed of the NEGIS are essential to understand its ice flow dynamics. We present a record of more than 8000 km of radar survey lines of multi-channel, ultra-wideband radio echo sounding data covering an area of 24 000 km2, centered on the drill site for the East Greenland Ice-core Project (EGRIP), in the upper part of the NEGIS catchment. Our data yield a new detailed model of ice-thickness distribution and basal topography in the region. The enhanced resolution of our bed topography model shows features which we interpret to be caused by erosional activity, potentially over several glacial–interglacial cycles. Off-nadir reflections from the ice–bed interface in the center of the ice stream indicate a streamlined bed with elongated subglacial landforms. Our new bed topography model will help to improve the basal boundary conditions of NEGIS prescribed for ice flow models and thus foster an improved understanding of the ice-dynamic setting.

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confidence: 99%

Bed topography and subglacial landforms in the onset region of the Northeast Greenland Ice Stream

et al. 2020

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“…Each range nadir line is collected at the Pulse Repetition Frequency (PRF) and processed in the along-track direction to generate 2D images of the subsurface. Azimuth processing reduces along-track clutter, increases the Signal-to-Noise ratio (SNR) and improves the azimuth resolution (Legarsky and Gogineni, 1998; Leuschen and others, 2000; Legarsky and others, 2001; Peters and others, 2007; Kusk and Dall, 2010). However, an unfortunate side-effect is that signal from steeply sloping layers may be lost (Holschuh and others, 2014).…”

Section: Introductionmentioning

confidence: 99%

Layer optimized SAR processing and slope estimation in radar sounder data

et al. 2019

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Englacial layers in Antarctica and Greenland are indicators of the dynamic, rheological and subglacial configuration of the ice sheets. Airborne radar sounder data is the primary remote sensing solution for directly observing englacial layers and structures at the glacier-catchment to ice-sheet scale. However, when traditional along-track synthetic aperture radar (SAR) processing is applied, steep layers can disappear, limiting the detectability and interpretability of englacial layer geometry. This study provides a reconstruction algorithm to address the problem of destructive phase interference during the radargram formation. We develop and apply a novel SAR processor optimized for layer detection that enhances the Signal-to-Noise ratio (SNR) of specular reflectors. The algorithm also enables the automatic estimation of layer slope. We demonstrate the algorithm using data acquired at the Institute Ice Stream, West Antarctica.

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“…Table 4 gives the digital down conversion and matched filter coefficients used for the various data segments. The frequency-wavenumber (or f-k migration algorithm) described in [61] is used to SAR process the data. After SAR processing, motion compensation in the squint direction is removed so that the SAR image represents the original phase center of the measurement.…”

Section: Data Processingmentioning

confidence: 99%

HF/VHF Radar Sounding of Ice from Manned and Unmanned Airborne Platforms

et al. 2018

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Ice thickness and bed topography of fast-flowing outlet glaciers are large sources of uncertainty for the current ice sheet models used to predict future contributions to sea-level rise. Due to a lack of coverage and difficulty in sounding and imaging with ice-penetrating radars, these regions remain poorly constrained in models. Increases in off-nadir scattering due to the highly crevassed surfaces, volumetric scattering (due to debris and/or pockets of liquid water), and signal attenuation (due to warmer ice near the bottom) are all impediments in detecting bed-echoes. A set of high-frequency (HF)/very high-frequency (VHF) radars operating at 14 MHz and 30-35 MHz were developed at the University of Kansas to sound temperate ice and outlet glaciers. We have deployed these radars on a small unmanned aircraft system (UAS) and a DHC-6 Twin Otter. For both installations, the system utilized a dipole antenna oriented in the cross-track direction, providing some performance advantages over other temperate ice sounders operating at lower frequencies. In this paper, we describe the platform-sensor systems, field operations, data-processing techniques, and preliminary results. We also compare our results with data from other ice-sounding radars that operate at frequencies both above (Center for Remote Sensing of Ice Sheets (CReSIS) Multichannel Coherent Depth Sounder (MCoRDS)) and below (Jet Propulsion Laboratory (JPL) Warm Ice Sounding Explorer (WISE)) our HF/VHF system. During field campaigns, both unmanned and manned platforms flew closely spaced parallel and repeat flight lines. We examine these data sets to determine image coherency between flight lines and discuss the feasibility of forming 2D synthetic apertures by using such a mission approach.

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SAR processing of radar echo sounder data

Cited by 20 publications

References 4 publications

Bed topography and subglacial landforms in the onset region of the Northeast Greenland Ice Stream

Bed topography and subglacial landforms in the onset region of the Northeast Greenland Ice Stream

Layer optimized SAR processing and slope estimation in radar sounder data

HF/VHF Radar Sounding of Ice from Manned and Unmanned Airborne Platforms

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