Antarctic Ice Sheet and Radar Altimetry: A Review

Rémy, Frédérique; Parouty, S.

doi:10.3390/rs1041212

Cited by 86 publications

(84 citation statements)

References 133 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These changes are small in amplitude and have a large spatial extension. Rémy and Parouty (2009) showed (by comparing ERS-2 and Envisat elevation trends) that they could vary depending on the observation period. They are attributed to variations in meteorological forcings.…”

Section: Along-track Processingmentioning

confidence: 99%

“…The contribution from this error is difficult to estimate. Further investigation is still needed for an independent validation of radar altimeter time series over ice sheets with respect to this phenomenon (Arthern and others, 2001;Rémy and Parouty, 2009). However, the overall good agreement between our values and those of Scott and others (2009) gives good confidence in the quality of our altimetry data.…”

Section: Measurement Accuracymentioning

confidence: 99%

“…The overall processing in itself is a least-square fit to the measured elevations (Rémy and Parouty, 2009).…”

Section: Along-track Processingmentioning

confidence: 99%

See 2 more Smart Citations

Dynamic thinning of Antarctic glaciers from along-track repeat radar altimetry

Flament¹,

Rémy²

2012

J. Glaciol.

Self Cite

164

182

View full text Add to dashboard Cite

ABSTRACT. Since 2002, the Envisat radar altimeter has measured the elevation of the Antarctic ice sheet with a repeat cycle of 35 days. This long and regular time series is processed using an along-track algorithm to depict in detail the spatial and temporal pattern of elevation change for the whole ice sheet. We use this dataset to examine the spatial and temporal pattern of Pine Island Glacier (PIG) thinning and compare it to the neighbouring glaciers. We also examine additional areas, especially in East Antarctica whose mass balance is poorly known. One advantage of the finer along-track spacing of measurements is that it reveals places of dynamic thinning in regions of rapid ice flow. We observe the acceleration of thinning on PIG. Over the entire basin, the volume loss increased from 7 km 3 a -1 during 2002-06 to $ $48 km 3 a -1 during 2006-10. We also observe accelerated thinning on the lower tens of kilometres of Thwaites Glacier, with a mean thinning of 0.18 m a -1 over its entire basin during our observation period. We confirm the dynamic thinning of Totten Glacier but we do not detect significantly accelerated thinning on any glacier elsewhere than on the coast of the Amundsen Sea.

show abstract

Section: Along-track Processingmentioning

confidence: 99%

Section: Measurement Accuracymentioning

confidence: 99%

See 1 more Smart Citation

Dynamic thinning of Antarctic glaciers from along-track repeat radar altimetry

Flament¹,

Rémy²

2012

J. Glaciol.

Self Cite

164

182

View full text Add to dashboard Cite

show abstract

“…Floating foam is far from being uniformly distributed over the wave height, and the shape of the waveform is no longer related in a simple way to P(η); a more accurate spatial description of the wave field processes is therefore needed. Neglecting this aspect necessarily implies that errors will arise in the estimation of both the H s and the SSL; this latter, in particular is very important because the precision needed for the geophysical applications [8][9][10] of SSL-e.g., sea level rise monitoring-is very high. These effects have therefore been the object of intense research over the years: the subject was indeed considered early as by Zheng et al [11].…”

Section: Figurementioning

confidence: 99%

Numerical Simulation of Whitecaps and Foam Effects on Satellite Altimeter Response

2014

View full text Add to dashboard Cite

Abstract:The determination of wave height by active satellite remote sensing, be it Synthetic Aperture Radar (SAR) or altimeter, has been a common practice for many years and is now imbedded on many meteorological and oceanographic forecasting systems. Despite their differences, all active sensors are based on the measurement of the Normalized Radar Cross Section (NRCS) of the sea surface, i.e., of its backscattering properties, which in turn depend on the wind velocity. At small and moderate wind speeds, the main mechanism is the formation of ripples (small scale waves); at higher speeds, whitecaps appear, and foam starts playing an essential role in determining NRCS. In the past few years much research effort has gone into clarifying these effects, thus improving the general quality of the measurements. Little work, however, has been devoted so far to consider the vertical spatial variation of backscattering properties, and in particular of the floating foam, over the sea surface. As it is shown in the present paper, the shape of the backscattered electromagnetic impulse in radar altimeters depends on the spatial distribution of foam over the water height in the sea waves and therefore the performance of these instruments in determining Significant Wave Height (H s ) and Sea Surface Level (SSL) is strongly affected by this effect. This work tackles these problems by making use of specially implemented numerical algorithms to simulate both sea surface processes and radar altimeter techniques. Results show that some causes of errors can be better understood and eventually corrected: in particular, the paper deals with the reconstruction of the electromagnetic Sea State Bias (SSB), the well known altimeter ranging error due to the presence of ocean waves on the sea surface.

show abstract

“…Indeed, the backscattering coefficient is a combination of two components, the "surface echo" and the "volume echo" (Brown, 1977;Remy et al, 2012). The former mainly depends on surface roughness and density of near-surface snow while the latter mainly depends on snow temperature, grain size and snowpack stratification (Remy and Parouty, 2009;Li and Zwally, 2011) over a certain depth that mainly depends on the radar frequency (e.g. less than one meter at Ka band and less than ten meters at Ku band (Remy et al, 2015)).…”

Section: Introductionmentioning

confidence: 99%

Seasonal variations of the backscattering coefficient measured by radar altimeters over the Antarctica Ice Sheet

Adodo¹,

Rémy²,

Picard³

2017

Preprint

View full text Add to dashboard Cite

Abstract. Spaceborne radar altimeter is a valuable tool for observing the Antarctica Ice Sheet. The radar wave penetration into the snow provides information both on the surface and the subsurface of the snowpack due to its dependence on the snow properties. However this penetration also induces a negative bias on the estimated surface elevation. Empirical corrections of this space and time-varying bias are usually based on the backscattering coefficient variability. We investigate the spatial and seasonal variations of the backscattering coefficient at the S (3.2 GHz), Ku (13.6 GHz) and Ka (37 GHz) bands. We identified two clearly marked zones over the continent, one with the maximum of Ku band backscattering coefficient in the winter and another with the maximum in the summer. To explain this, we performed a sensitivity study of the backscattering coefficient at the S, Ku and Ka bands to surface snow density, snow temperature and snow grain size using an electromagnetic model. The results show that the seasonal cycle of the backscattering coefficient at the Ka band, is dominated by the volume echo and is mainly explained by snow temperature. In contrast, the cycle is dominated by the surface echo at the S band. At Ku band, which intermediate in terms of wavelength between S and Ka bands, the seasonal cycle is in the first zone dominated by the volume echo and by the surface echo in the second one. Such seasonal and spatial variations of the backscattering coefficient at different radar frequencies should be taken into account the for more precise estimation of the surface elevation changes.

show abstract

Antarctic Ice Sheet and Radar Altimetry: A Review

Cited by 86 publications

References 133 publications

Dynamic thinning of Antarctic glaciers from along-track repeat radar altimetry

Dynamic thinning of Antarctic glaciers from along-track repeat radar altimetry

Numerical Simulation of Whitecaps and Foam Effects on Satellite Altimeter Response

Seasonal variations of the backscattering coefficient measured by radar altimeters over the Antarctica Ice Sheet

Contact Info

Product

Resources

About