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On Closure Phase and Systematic Bias in Multilooked SAR Interferometry

Zheng, Yujie and Fattahi, Heresh and Agram, Piyush and Simons, Mark and Rosen, Paul (2022) On Closure Phase and Systematic Bias in Multilooked SAR Interferometry. IEEE Transactions on Geoscience and Remote Sensing, 60 . Art. No. 5226611. ISSN 0196-2892. doi:10.1109/tgrs.2022.3167648.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Zheng, Yujie0000-0001-9013-451X
Fattahi, Heresh0000-0001-6926-4387
Agram, Piyush0000-0003-0711-0264
Simons, Mark0000-0003-1412-6395
Rosen, Paul0000-0002-4558-6004
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 The precipitation data can be downloaded from 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.
Group:Seismological Laboratory
Funding AgencyGrant Number
Subject Keywords:Closure phase, interferometric synthetic aperture radar (InSAR), InSAR time series, phase consistency, systematic bias
Record Number:CaltechAUTHORS:20220616-959320500
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Official Citation:Y. Zheng, H. Fattahi, P. Agram, M. Simons and P. Rosen, "On Closure Phase and Systematic Bias in Multilooked SAR Interferometry," in IEEE Transactions on Geoscience and Remote Sensing, vol. 60, pp. 1-11, 2022, Art no. 5226611, doi: 10.1109/TGRS.2022.3167648
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115183
Deposited By: Tony Diaz
Deposited On:21 Jun 2022 22:28
Last Modified:22 Jun 2022 16:19

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