The wavenumber shift in SAR interferometry

Gatelli, F.; Guamieri, A.M.; Parizzi, F.; Pasquali, Paolo; Prati, C.; Rocca, F.

doi:10.1109/36.298013

Cited by 592 publications

(351 citation statements)

References 8 publications

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“…This is especially important for interferograms that mix ERS-1 and ERS-2 images, as the two satellites used different Doppler frequencies. Range spectrum filtering for the two SLC images was applied to account for the spectral shift induced by the slight difference in incidence angle between the SLC images [Gatelli et al, 1994], only that common to the two being retained. This optimization procedure improved the interferometric coherence (H.…”

Section: Methodsmentioning

confidence: 99%

Synthetic aperture radar interferometry of Okmok volcano, Alaska: Radar observations

Lü¹,

Mann²,

Freymueller³

et al. 2000

J. Geophys. Res.

107

110

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Abstract. ERS-1/ERS-2 synthetic aperture radar interferometry was used to study the 1997 eruption of Okmok volcano in Alaska. First, we derived an accurate digital elevation model (DEM) using a tandem ERS-1/ERS-2 image pair and the preexisting DEM. Second, by studying changes in interferometric coherence we found that the newly erupted lava lost radar coherence for 5-17 months after the eruption. This suggests changes in the surface backscattering characteristics and was probably related to cooling and compaction processes. Third, the atmospheric delay anomalies in the deformation interferograms were quantitatively assessed. Atmospheric delay anomalies in some of the interferograms were significant and consistently smaller than one to two fringes in magnitude. For this reason, repeat observations are important to confidently interpret small geophysical signals related to volcanic activities. Finally, using two-pass differential interferometry, we analyzed the preeruptive inflation, coeruptive deflation, and posteruptive inflation and confirmed the observations using independent image pairs. We observed more than 140 cm of subsidence associated with the 1997 eruption. This subsidence occurred between 16 months before the eruption and 5 months after the eruption, was preceded by-•18 cm of uplift between 1992 and 1995 centered in the same location, and was followed by •10 cm of uplift between September 1997 and 1998. The best fitting model suggests the magma reservoir resided at 2.7 km depth beneath the center of the caldera, which was -5 km from the eruptive vent. We estimated the volume of the erupted material to be 0.055 km 3 and the average thickness of the erupted lava to be---7.4 m.

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Section: Methodsmentioning

confidence: 99%

Synthetic aperture radar interferometry of Okmok volcano, Alaska: Radar observations

Lü¹,

Mann²,

Freymueller³

et al. 2000

J. Geophys. Res.

107

110

View full text Add to dashboard Cite

show abstract

“…These noises derive from variations in the imaged reflectivities of the two acquisitions; they are mainly due to temporal changes in the repeat-pass interval, and also to the acquisition geometry (baseline, crossed orbits), "volume scattering" etc. [17,18,16]. These "scene noise" sources add up to the target reflectivity, quite differently from the other "system noises" that add up to acquired data, as Fig.…”

Section: Optimizing Interferometric Qualitymentioning

confidence: 99%

“…This may be the case when the two AAP are shifted or when one of the two images is synthesized from a SAR focused image [19]. This decorrelation can be expressed in terms of the normalized correlation coefficient between the two FIRF's, and can then be converted to phase noise according to [17,18,16]. It can be measured by adapting the "CEOS phase-preserving test" described in [20,21].…”

Section: Phase Preserving Processingmentioning

confidence: 99%

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Optimal "focusing" for low resolution ScanSAR

Guarnieri

Guccione

2001

IEEE Trans. Geosci. Remote Sensing

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“…Next consider a long-baseline interferogram with rugged terrain so the slope is high and the magnitude of the phase gradient can approach n: rad per pixel; so again, the correlation (equation (A15)) will be low [Gatelli et al, 1994]. In this case, one could improve the estimated correlation by removing the phase due to the topography.…”

mentioning

confidence: 99%

Phase gradient approach to stacking interferograms

Sandwell¹,

Price²

1998

J. Geophys. Res.

237

117

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Abstract. The phase gradient approach is used to construct averages and differences of interferograms without phase unwrapping. Our objectives for change detection are to increase fringe clarity and decrease errors due to tropospheric and ionospheric delay by averaging many interferograms. The standard approach requires phase unwrapping, scaling the phase according to the ratio of the perpendicular baseline, and finally forming the average or difference; however, unique phase unwrapping is usually not possible. Since the phase gradient due to topography is proportional to the perpendicular baseline, phase unwrapping is unnecessary prior to averaging or differencing. Phase unwrapping may be needed to interpret the results, but it is delayed until all of the largest topographic signals are removed. We demonstrate the method by averaging and differencing six interferograms having a suite of perpendicular baselines ranging from 18 to 406 m. Cross-spectral analysis of the difference between two Tandem interferograms provides estimates of spatial resolution, which are used to design prestack filters. A wide range of perpendicular baselines provides the best topographic recovery in terms of accuracy and coverage. Outside of mountainous areas the topography has a relative accuracy of better than 2 m. Residual interferograms (single interferogram minus stack) have tilts across the unwrapped phase that are typically 50 mm in both range and azimuth, reflecting both orbit error and atmospheric delay. Smaller-scale waves with amplitudes of 15 mm are interpreted as atmospheric lee waves. A few Global Positioning System (GPS) control points within a frame could increase the precision to -20 mm for a single interferogram; further improvements may be achieved by stacking residual interferograms.

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The wavenumber shift in SAR interferometry

Cited by 592 publications

References 8 publications

Synthetic aperture radar interferometry of Okmok volcano, Alaska: Radar observations

Synthetic aperture radar interferometry of Okmok volcano, Alaska: Radar observations

Optimal "focusing" for low resolution ScanSAR

Phase gradient approach to stacking interferograms

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