Atmospheric Artifact Compensation in Ground-Based DInSAR Applications

Pipia, Luca; Fábregas, X.; Aguasca, A.; López-Martínez, Carlos

doi:10.1109/lgrs.2007.908364

Cited by 89 publications

(53 citation statements)

References 7 publications

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“…In relatively flat terrain and over short distances (few hundred metres), it is sometimes assumed that the atmosphere is homogeneous and that it is the range distance that determines the change in refractivity, creating a linear ramp in range (e.g. Pipia et al 2008). However, for a vertically stratified atmosphere intersected by steep topography, as in our case, we expect the change in refractivity vertically to play a role.…”

Section: Multi-hour Interferogram and A Stratified Refractivity Modelmentioning

confidence: 66%

The Variability of Refractivity in the Atmospheric Boundary Layer of a Tropical Island Volcano Measured by Ground-Based Interferometric Radar

Wadge

Costa

Pascal

et al. 2016

Boundary-Layer Meteorol

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For 24 h we measured continuously the variability of atmospheric refractivity over a volcano on the tropical island of Montserrat using a ground-based radar interferometer. We observed variations in phase that we interpret as due to changing water vapour on the propagation path between the radar and the volcano and we present them here in the context of the behaviour of the atmospheric boundary layer over the island. The water vapour behaviour was forced by diurnal processes, the passage of a synoptic-scale system and the presence of a plume of volcanic gas. The interferometer collected images of amplitude and phase every minute. From pairs of phase images, interferograms were calculated and analyzed every minute and averaged hourly, together with contemporaneous measurements of zenith delays estimated from a network of 14 GPS receivers. The standard deviation of phase at two sites on the volcano surface spanned a range of about 1-5 radians, the lowest values occurring at night on the lower slopes and the highest values during the day on the upper slopes. This was also reflected in spatial patterns of variability. Two-dimensional profiles of radar-measured delays were modelled using an atmosphere with water vapour content decreasing upwards and water vapour variability increasing upwards. Estimates of the effect of changing water vapour flux from the volcanic plume indicate that it should contribute only a few percent to this atmospheric variability. A diurnal cycle within the lower boundary layer producing a turbulence-dominated mixed layer during the day and stable layers at night is consistent with the observed refractivity.

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Section: Multi-hour Interferogram and A Stratified Refractivity Modelmentioning

confidence: 66%

The Variability of Refractivity in the Atmospheric Boundary Layer of a Tropical Island Volcano Measured by Ground-Based Interferometric Radar

Wadge

Costa

Pascal

et al. 2016

Boundary-Layer Meteorol

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“…Different meteorological conditions have different atmospheric refractive index values, which can cause some loss of measurement accuracy. Therefore, if there is a need for the periodic monitoring of bridges in different measuring times using ground-based microwave interferometry, it is necessary to improve the measurement accuracy of the dynamic deflection of bridges by the use of atmospheric parameters correction, such as the Permanent Scatterers technique [38][39][40] and model-based approach [10,41]. This can improve the contrast of different period data.…”

Section: Discussionmentioning

confidence: 99%

Dynamic Monitoring and Vibration Analysis of Ancient Bridges by Ground-Based Microwave Interferometry and the ESMD Method

Liu

Yang

et al. 2018

Remote Sensing

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Abstract:In this paper, we propose to conduct a dynamic monitoring and vibration analysis of ancient bridges by means of ground-based microwave interferometry and the extreme-point symmetric mode decomposition (ESMD) method. Ground-based microwave interferometry, a novel non-contact technology with a high accuracy, is used to acquire dynamic time series displacements with environmental excitation factors and a transient load with a car, respectively. The ESMD method, a new alternative to the Hilbert-Huang transform (HHT), is adopted to conduct the instantaneous vibration analysis of Zhaozhou Bridge. Firstly, a series of intrinsic mode functions (IMFs) are obtained together with an optimal adaptive global mean (AGM) curve by using a mode symmetric about the maxima and minima points. Secondly, the instantaneous frequency of each IMF is obtained by the use of a direct interpolation algorithm, which can reconcile the conflict between the period and the frequency for the traditional time-frequency analysis methods. As a representative case, Zhaozhou Bridge, a well-known Chinese ancient bridge constructed more than 1400 years ago, is studied in detail. Four kinds of dynamic time series displacements-two of them acquired by considering only environmental excitation factors for the mid-span and 1/4-span points and the others obtained with the transient load of a car for the mid-span and 1/4-span points-are selected to pursue a comparison of the decomposed IMFs and the instantaneous frequencies to perform the instantaneous vibration analysis of Zhaozhou Bridge. By comparing the results obtained with HHT for the decomposed IMFs and the instantaneous frequencies, the results show that the proposed method has a powerful ability to evaluate the instantaneous dynamic response of ancient bridges.

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“…The thermal noise contribution γ th depends on the SNR and γ blur accounts for the cross-range image blurring. As γ th is negligible because of the high power transmitted and the reduced dimensions of the illuminated scene [30], the degradation of the coherence γ can be related to the temporal decorrelation occurred between different acquisitions and the blurring effect in the cross-range direction during the scanning time. Assuming that the scenario has not changed during the short period of time between measurements, which means that there is no temporal decorrelation between images, the blurring effect γ blur is, in our case, mainly responsible for the decorrelation between images and the largest contributor to the degradation of the coherence.…”

Section: B Image Decorrelation Characterizationmentioning

confidence: 99%

Impact of Wind-Induced Scatterers Motion on GB-SAR Imaging

Lort

Aguasca

López-Martínez

et al. 2018

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Abstract-Ground-based synthetic aperture radar (GB-SAR) sensors represent a cost-effective solution for change detection and ground displacement assessment of small-scale areas in real-time early warning applications. GB-SAR systems based on stepped linear frequency modulated continuous wave signals have led to several improvements such as a significant reduction of the acquisition time. Nevertheless, the acquisition time is still long enough to force a degradation of the quality of the reconstructed images because of possible short-term variable reflectivity of the scenario. This reduction of the quality may degrade the differential interferometric detection process. In scenarios where interesting targets are surrounded by vegetation, this is normally related to atmospheric conditions, in particular, the wind. The present paper characterizes the effect of the short-term variable reflectivity in the GB-SAR image reconstruction and evaluates its equivalent blurring effect, the decorrelation introduced in the SAR images, and the degradation of the extracted parameters. In order to validate the results, the study assesses different GB-SAR images obtained with the RISKSAR-X sensor, which has been developed by the Universitat Politècnica de Catalunya.Index Terms-Blurring, coherence, differential synthetic aperture radar (SAR) interferometry (DInSAR), ground-based synthetic aperture radar (GB-SAR), temporal decorrelation.

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Atmospheric Artifact Compensation in Ground-Based DInSAR Applications

Cited by 89 publications

References 7 publications

The Variability of Refractivity in the Atmospheric Boundary Layer of a Tropical Island Volcano Measured by Ground-Based Interferometric Radar

The Variability of Refractivity in the Atmospheric Boundary Layer of a Tropical Island Volcano Measured by Ground-Based Interferometric Radar

Dynamic Monitoring and Vibration Analysis of Ancient Bridges by Ground-Based Microwave Interferometry and the ESMD Method

Impact of Wind-Induced Scatterers Motion on GB-SAR Imaging

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