Design, Development, Field Observations, and Preliminary Results of the Coherent Antarctic Radar Depth Sounder (CARDS) of the University of Kansas, U.S.A.

Raju, G. S.; Xin, W.; Moore, Robert K.

doi:10.1017/s0022143000009503

Cited by 21 publications

(10 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Noteworthy early work includes the high‐resolution, two‐dimensional backscatter images of a grounding line produced with 120 MHz side‐looking SAR [ Musil and Doake , 1987]. Coherent radar sounders with digital acquisition were developed around the same time allowing for real‐time unfocused SAR imaging of ice sheets [e.g., Schultz et al , 1987; Raju et al , 1990]. Focused SAR processing has also been implemented on radar data from glaciers and ice sheets [e.g., Hamran and Aarholt , 1993; Legarsky et al , 2001].…”

Section: Background and Radar Instrumentsmentioning

confidence: 99%

Analysis techniques for coherent airborne radar sounding: Application to West Antarctic ice streams

Peters¹

2005

J. Geophys. Res.

211

302

View full text Add to dashboard Cite

[1] Analysis of coherent radar sounding echoes from polar ice sheets can provide information suitable for classifying the subglacial environment. Echoes from a general interface consist of both specularly reflected and diffusely scattered contributions. Specular reflection results from smooth uniform interfaces, whereas diffuse scattering results from rough nonuniform interfaces and inhomogeneous media. This article discusses how these phenomena are important to the acquisition and analysis of coherent radar sounding data. Reflection results are presented from airborne surveys conducted in 1987 over the downstream portions of Whillans Ice Stream and Ice Stream C, West Antarctica. Additionally, reflection and scattering analyses along with new results are presented for repeat profiles flown in 2001 over Ice Stream C. Analysis methods include using echo amplitudes to compute reflection coefficients which are used for inferring the dielectric properties of the subglacial material. Echo phase analysis provides the locations of dominant scattering centers which relate to reflection or scattering from the interface as well as provide interface roughness estimates. Comparison of low-and high-resolution imaging obtained from synthetic aperture radar techniques indicates a reflecting and/or scattering interface. Combining the results from these independent analyses provides classification of the subglacial environment. Classified regions include smooth seawater, smooth saturated sediments, accreted marine ice, rough bottom crevasses, mixed conditions with partial subglacial water, and dry frozen conditions.

show abstract

Section: Background and Radar Instrumentsmentioning

confidence: 99%

Analysis techniques for coherent airborne radar sounding: Application to West Antarctic ice streams

Peters¹

2005

J. Geophys. Res.

211

302

View full text Add to dashboard Cite

show abstract

“…Ice thickness is a key variable in the timedependent equation of continuity and is essential to any study of ice sheet dynamics. Raju et al [1990] developed a coherent radar sounder for measurements in the Antarctic. We used this system to collect ice thickness data during the 1993 field season.…”

Section: Introductionmentioning

confidence: 99%

Coherent radar ice thickness measurements over the Greenland ice sheet

Gogineni¹,

Tammana²,

Braaten³

et al. 2001

J. Geophys. Res.

154

129

View full text Add to dashboard Cite

Abstract. We developed two 150-MHz coherent radar depth sounders for ice thickness measurements over the Greenland ice sheet. We developed one of these using connectorized components and the other using radio frequency integrated circuits (RFICs). Both systems are designed to use pulse compression techniques and coherent integration to obtain the high sensitivity required to measure the thickness of more than 4 km of cold ice. We used these systems to collect radar data over the interior and margins of the ice sheet and several outlet glaciers. We operated both radar systems on the NASA P-3B aircraft equipped with GPS receivers. Radar data are tagged with GPS-derived location information and are collected in conjunction with laser altimeter measurements. We have reduced all data collected since 1993 and derived ice thickness along all flight lines flown in support of Program for Regional Climate Assessment (PARCA) investigations and the North Greenland Ice Core Project. Radar echograms and derived ice thickness data are placed on a server at the University of Kansas (http://tornado. rsl.ukans.edu/Greenlanddata.htm) for easy access by the scientific community. We obtained good ice thickness information with an accuracy of _+ 10 m over 90% of the flight lines flown as a part of the PARCA initiative. In this paper we provide a brief description of the system along with samples of data over the interior, along the 2000-m contour line in the south and from a few selected outlet glaciers. IntroductionIn 1991, NASA started a polar research initiative aimed at determining the mass balance of the Greenland ice sheet. This program consisted of coordinated surface, airborne, and spaceborne measurements for determining the mass balance of the ice sheet. The initial airborne program consisted of a laser altimeter and a Ku-band radar altimeter for measuring surface elevation of the ice sheet along selected flight lines. In 1993 the airborne instrumentation suite was expanded to include a radar depth sounder to collect ice thickness data along the same flight lines. Ice thickness is a key variable in the timedependent equation of continuity and is essential to any study of ice sheet dynamics.Raju et al.[1990] developed a coherent radar sounder for measurements in the Antarctic. We used this system to collect ice thickness data during the 1993 field season. Although the system collected good quality data in certain areas in the north and central parts of the ice sheet, its performance was less than optimum for obtaining ice thickness data over a few parts of the ice sheet in southern Greenland. These are in temperate areas of the ice sheet with thick, warm ice. To overcome its limitations and improve its performance, we developed two new systems: one using connectorized components and the other using radio frequency integrated circuits (RFICs). The transmitter and receiver prototypes for the system using RFICs were developed by senior undergraduate students as part of a capstone design project. We used these prototypes to devel...

show abstract

“…Moreover differential GPS measurements allow precise determination of the geographical position of the acquired traces, reducing uncertainties to ±5 m and ±10 cm in post-processing. In 1990 the first coherent RES system was developed by the University of Kansans and tested in Antarctica (Raju 1990, Cogineni 1998. A coherent radar detects both the amplitude and phase of the radar signal.…”

Section: Radar Technology For Glaciologymentioning

confidence: 99%