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Published April 18, 2022 | Accepted Version
Journal Article Open

On Closure Phase and Systematic Bias in Multilooked SAR Interferometry

Abstract

In this article, we investigate the link between the closure phase and the observed systematic bias in deformation modeling with multilooked SAR interferometry. Multilooking or spatial averaging is commonly used to reduce stochastic noise over a neighborhood of distributed scatterers in interferometric synthetic aperture radar (InSAR) measurements. However, multilooking may break consistency among a triplet of interferometric phases formed from three acquisitions leading to a residual phase error called closure phase. Understanding the cause of closure phase in multilooked InSAR measurements and the impact of closure phase errors on the performance of InSAR time-series algorithms is crucial for quantifying the uncertainty of ground displacement time series derived from InSAR measurements. We develop a model that consistently explains both closure phase and systematic bias in multilooked interferometric measurements. We show that nonzero closure phase can be an indicator of temporally inconsistent physical processes that alter both phase and amplitude of interferometric measurements. We propose a method to estimate the systematic bias in the InSAR time series with generalized closure phase measurements. We validate our model with a case study in Barstow-Bristol Trough, CA, USA. We find systematic differences on the order of cm/year between InSAR time-series results using subsets of varying maximum temporal baselines. We show that these biases can be identified and accounted for.

Additional Information

© 2022 IEEE. Manuscript received October 6, 2021; revised January 13, 2022, February 28, 2022, and March 28, 2022; accepted April 8, 2022. Date of publication April 18, 2022; date of current version May 2, 2022. The authors would like to dedicate this article to the memory of Michael Rosen, whose work on the Bristol dry lake inspired the choice of the test site used in this work. This work was supported by the Jet Propulsion Laboratory Advanced Concept Funds. Sentinel-1 data used in this study can be downloaded from https://search.asf.alaska.edu/. The precipitation data can be downloaded from https://www.ncei.noaa.gov/. The research was partly carried out at the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA, under a contract with the National Aeronautics and Space Administration. The authors would like to thank the anonymous reviewers for their constructive comments that helped to improve this manuscript.

Attached Files

Accepted Version - On_Closure_Phase_and_Systematic_Bias_in_Multi-looked_SAR_Interferometry_acc.pdf

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On_Closure_Phase_and_Systematic_Bias_in_Multi-looked_SAR_Interferometry_acc.pdf

Additional details

Created:
August 22, 2023
Modified:
October 24, 2023