Coherent radar ice thickness measurements over the Greenland ice sheet

Gogineni, S.; Tammana, D.; Braaten, D.; Leuschen, C.; Akins, T.; Legarsky, J.; Kanagaratnam, P.; Stiles, James M.; Allen, Christopher T.; Jezek, K.

doi:10.1029/2001jd900183

Cited by 155 publications

(132 citation statements)

References 13 publications

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“…Ice-sheet velocity snapshots have been widely measured by using interferometric synthetic aperture radar (InSAR) with high (<3%) accuracy (62,63) and relatively low (annual or longer) frequency. The thickness of many ice streams has been directly measured by using airborne radar with high (~10 m) accuracy (64). Nonetheless, there are many ice-sheet outlet glaciers for which such data do not exist; in these regions, less accurate methods are used to calculate thickness with uncertainties in the range of 80 to 120 m (18,55).…”

Section: Methodsmentioning

confidence: 99%

A Reconciled Estimate of Ice-Sheet Mass Balance

Shepherd

Ivins

Geruo

et al. 2012

Science

1,330

1,260

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Warming and Melting Mass loss from the ice sheets of Greenland and Antarctica account for a large fraction of global sea-level rise. Part of this loss is because of the effects of warmer air temperatures, and another because of the rising ocean temperatures to which they are being exposed. Joughin et al. (p. 1172 ) review how ocean-ice interactions are impacting ice sheets and discuss the possible ways that exposure of floating ice shelves and grounded ice margins are subject to the influences of warming ocean currents. Estimates of the mass balance of the ice sheets of Greenland and Antarctica have differed greatly—in some cases, not even agreeing about whether there is a net loss or a net gain—making it more difficult to project accurately future sea-level change. Shepherd et al. (p. 1183 ) combined data sets produced by satellite altimetry, interferometry, and gravimetry to construct a more robust ice-sheet mass balance for the period between 1992 and 2011. All major regions of the two ice sheets appear to be losing mass, except for East Antarctica. All told, mass loss from the polar ice sheets is contributing about 0.6 millimeters per year (roughly 20% of the total) to the current rate of global sea-level rise.

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Section: Methodsmentioning

confidence: 99%

A Reconciled Estimate of Ice-Sheet Mass Balance

Shepherd

Ivins

Geruo

et al. 2012

Science

1,330

1,260

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“…So, it is unlikely that there is a strong horizontal preference in the ice crystal fabric [15]. The second is that a ground-based version of the University of Kansas 150-MHz coherent radar depth sounder (CoRDS) [16] mapped an ice thickness grid over NGRIP during the same field season, and no preference in antenna orientation was found (transmit and receive antennas were always copolarized, however). Unfortunately, we did not take cross-polarization measurements to determine depolarization, so the extent to which it affected our measurements is unknown.…”

Section: Ice Sheet Rf Extinctionmentioning

confidence: 99%

Wideband Measurements of Ice Sheet Attenuation and Basal Scattering

Paden

Allen

Gogineni

et al. 2005

IEEE Geosci. Remote Sensing Lett.

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Abstract-We are developing a multifrequency multistatic synthetic aperture radar (SAR) for determining polar ice sheet basal conditions. To obtain data for designing and optimizing radar performance, we performed field measurements with a network-analyzer-based system during the 2003 field season at the North Greenland Ice Core Project camp (75.1 N and 42.3 W). From the measurements, we determine the ice sheet complex transfer function over the frequency range from 110-500 MHz by deconvolving out the system transfer function. Over this frequency range, we observe an increase in total loss of 8 2 5 dB using a linear regression to the log-scale data. With the ice sheet transfer function and an ice extinction model, we estimate the return loss from the basal surface to be approximately 37 dB. These measurements have broad applicability to interpreting radar-sounding data, which are widely used in glaciological studies of the polar ice sheets. These data have also been used in the link budget for the design considerations of the multifrequency multistatic SAR system. Index Terms-Ice, ultrahigh frequency (UHF) measurements, very high frequency (VHF) measurements.

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“…Ice thickness for Helheim Glacier was obtained in 2001 and 2008 by the University of Kansas Coherent Radar Depth Sounder (CoRDS) (Gogineni et al, 2001;Howat et al, 2005). For Fenris and Midgård glaciers, for which no thickness data are available, ice thickness at the start of the time series was estimated from the height of the calving front assuming a grounded ice front at hydrostatic equilibrium and densities of ice and sea water of 910 and 1027 kg m 3 , respectively.…”

Section: Satellite-derived Ice Dischargementioning

confidence: 99%

Freshwater flux to Sermilik Fjord, SE Greenland

et al. 2010

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Abstract. Terrestrial inputs of freshwater flux to Sermilik Fjord, SE Greenland, were estimated, indicating ice discharge to be the dominant source of freshwater. A freshwater flux of 40.4 ± 4.9×10 9 m 3 y −1 was found (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008), with an 85% contribution originated from ice discharge (65% alone from Helheim Glacier), 11% from terrestrial surface runoff (from melt water and rain), 3% from precipitation at the fjord surface area, and 1% from subglacial geothermal and frictional melting due to basal ice motion. The results demonstrate the dominance of ice discharge as a primary mechanism for delivering freshwater to Sermilik Fjord. Time series of ice discharge for Helheim Glacier, Midgård Glacier, and Fenris Glacier were calculated from satellitederived average surface velocity, glacier width, and estimated ice thickness, and fluctuations in terrestrial surface freshwater runoff were simulated based on observed meteorological data. These simulations were compared and bias corrected against independent glacier catchment runoff observations. Modeled runoff to Sermilik Fjord was variable, ranging from 2.9 ± 0.4×10 9 m 3 y −1 in 1999 to 5.9 ± 0.9×10 9 m 3 y −1 in 2005. The sub-catchment runoff of the Helheim Glacier region accounted for 25% of the total runoff to Sermilik Fjord. The runoff distribution from the different sub-catchments suggested a strong influence from the spatial variation in glacier coverage, indicating high runoff volumes, where glacier cover was present at low elevations.

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Coherent radar ice thickness measurements over the Greenland ice sheet

Cited by 155 publications

References 13 publications

A Reconciled Estimate of Ice-Sheet Mass Balance

A Reconciled Estimate of Ice-Sheet Mass Balance

Wideband Measurements of Ice Sheet Attenuation and Basal Scattering

Freshwater flux to Sermilik Fjord, SE Greenland

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