Correction of ionospheric distortions in low frequency interferometric SAR data

Kim, Jun Su; Danklmayer, Andreas; Papathanassiou, Konstantinos

doi:10.1109/igarss.2011.6049353

Cited by 17 publications

(11 citation statements)

References 3 publications

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“…One measure of the accuracy of this correction is the coherence between the HH and VH channels [27], defined as In the absence of FR, this should be zero for scatterers with reflection symmetry, and it has a sharp minimum at Ω = 0 • as FR varies, whatever the dominant scattering mechanism. (Another possible measure is the cross-polarization (cross-pol) coherence, γ hv−vh , defined similarly to (20), which should be unity in the absence of FR.…”

Section: Fr Estimator Performance On Bees Images With No System Ermentioning

confidence: 99%

The Accuracy of Faraday Rotation Estimation in Satellite Synthetic Aperture Radar Images

Rogers

Quegan

2014

IEEE Trans. Geosci. Remote Sensing

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Spaceborne linearly polarimetric synthetic aperture radar (SAR) provides information about surface properties and scatterer types by measuring the covariances between images formed using orthogonally polarized radio waves. However, ionospheric Faraday rotation (FR) and system calibration errors alter the balance in the polarimetric channels and distort the covariance matrix. Since FR angles are greater at lower radio frequencies, this paper focuses on the Biomass satellite, which is the European Space Agency's 7th Earth Explorer mission and will carry a P-band (435 MHz) polarimetric SAR. Its primary objective is to measure forest biomass density by combining estimates derived from the polarimetric covariance matrix with estimates based on measuring forest height with polarimetric interferometry and exploiting height-biomass allometric relations. The accuracy of four methods for estimating FR from polarimetric SAR is assessed using simulated images of forest with a range of biomass densities and system errors (H/V channel imbalances, antenna crosstalk, and noise) and over a large spread of FR angles. All methods have biases dependent on the FR, the relative phases of the crosstalk components, and the channel imbalance phase. The best performing method estimates FR to better than 5 • under worst case system errors at all FR angles, so the accuracy of biomass density estimates should not be significantly affected. However, crosstalk phases are predicted to vary greatly across the Biomass antenna beam, and this could potentially cause the FR bias to vary by several degrees across the swath. These effects may occur even for the small values of FR met in L-band data.

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Section: Fr Estimator Performance On Bees Images With No System Ermentioning

confidence: 99%

The Accuracy of Faraday Rotation Estimation in Satellite Synthetic Aperture Radar Images

Rogers

Quegan

2014

IEEE Trans. Geosci. Remote Sensing

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“…Anisotropic filters or adaptive filters could help to increase the accuracy without introducing biases. The combination of different ionosphere estimation methods is also a possibility that is being studied [4], [9].…”

Section: B Filteringmentioning

confidence: 99%

“…The range phase-group delay difference method estimates the ionosphere, taking advantage of the fact that the ionospheric phase and group delays have opposite signs, unlike groundrelated phase and group delays, which have the same sign [5], [7]. The azimuth shift method exploits the proportional relation between differential azimuth shift and the azimuth derivative of the differential ionosphere [7]- [9]. Multiple aperture interferometry is sometimes used to estimate the azimuth shifts and can be considered an equivalent method [10].…”

Section: Introductionmentioning

confidence: 99%

Toward Operational Compensation of Ionospheric Effects in SAR Interferograms: The Split-Spectrum Method

Gomba

Parizzi

Zan

et al. 2016

IEEE Trans. Geosci. Remote Sensing

175

176

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The differential ionospheric path delay is a major error source in L-band interferograms. It is superimposed to topography and ground deformation signals, hindering the measurement of geophysical processes. In this paper, we proceed toward the realization of an operational processor to compensate the ionospheric effects in interferograms. The processor should be robust and accurate to meet the scientific requirements for the measurement of geophysical processes, and it should be applicable on a global scale. An implementation of the split-spectrum method, which will be one element of the processor, is presented in detail, and its performance is analyzed. The method is based on the dispersive nature of the ionosphere and separates the ionospheric component of the interferometric phase from the nondispersive component related to topography, ground motion, and tropospheric path delay. We tested the method using various Advanced Land Observing Satellite Phased-Array type L-band synthetic aperture radar interferometric pairs with different characteristics: high to low coherence, moving and nonmoving terrains, with and without topography, and different ionosphere states. Ionospheric errors of almost 1 m have been corrected to a centimeter or a millimeter level. The results show how the method is able to systematically compensate the ionospheric phase in interferograms, with the expected accuracy, and can therefore be a valid element of the operational processor.

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“…The ionospheric phase distortion and Faraday Rotation (FR) are both proportional to the total electron content (TEC) [2], [3], [4], which characterises the state of the ionosphere. The one-way FR, , is linked to TEC as 2)…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Estimation and correction of scintillation effects on spaceborne P-band SAR images

Kim

Papathanassiou

Quegan

et al. 2012

2012 IEEE International Geoscience and Remote Sensing Symposium

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A correction method for distortions induced by ionospheric scintillation effects on P-band quad-pol synthetic aperture radar (SAR) data acquired in polar and high latitude regions is presented. For this the estimation of the Faraday rotation (FR) is converted to ionospheric phase and used for the correction of the scintillation. The correction is performed on partially focused SLC data in order to compensate the ionosphere-induced phase and the distortion of the timeDoppler history. The degree of defocusing depends on the altitude of the ionosphere. The performance of the new correction method is tested on P-band simulated data for various ionospheric scenarios.

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Correction of ionospheric distortions in low frequency interferometric SAR data

Cited by 17 publications

References 3 publications

The Accuracy of Faraday Rotation Estimation in Satellite Synthetic Aperture Radar Images

The Accuracy of Faraday Rotation Estimation in Satellite Synthetic Aperture Radar Images

Toward Operational Compensation of Ionospheric Effects in SAR Interferograms: The Split-Spectrum Method

Estimation and correction of scintillation effects on spaceborne P-band SAR images

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