A Network-Based Enhanced Spectral Diversity Approach for TOPS Time-Series Analysis

Abstract

Abstract-For multitemporal analysis of synthetic aperture radar (SAR) images acquired with a terrain observation by progressive scan (TOPS) mode, all acquisitions from a given satellite track must be coregistered to a reference coordinate system with accuracies better than 0.001 of a pixel (assuming full SAR resolution) in the azimuth direction. Such a high accuracy can be achieved through geometric coregistration, using precise satellite orbits and a digital elevation model, followed by a refinement step using a time-series analysis of coregistration errors. These errors represent the misregistration between all TOPS acquisitions relative to the reference coordinate system. We develop a workflow to estimate the time series of azimuth misregistration using a network-based enhanced spectral diversity (NESD) approach, in order to reduce the impact of temporal decorrelation on coregistration. Example time series of misregistration inferred for five tracks of Sentinel-1 TOPS acquisitions indicates a maximum relative azimuth misregistration of less than 0.01 of the full azimuth resolution between the TOPS acquisitions in the studied areas. Standard deviation of the estimated misregistration time series for different stacks varies from 1.1e-3 to 2e-3 of the azimuth resolution, equivalent to 1.6-2.8 cm orbital uncertainty in the azimuth direction. These values fall within the 1-sigma orbital uncertainty of the Sentinel-1 orbits and imply that orbital uncertainty is most likely the main source of the constant azimuth misregistration between different TOPS acquisitions. We propagate the uncertainty of individual misregistration estimated with ESD to the misregistration time series estimated with NESD and investigate the different challenges for operationalizing NESD.Index Terms-Coregistration, interferometric synthetic aperture radar (InSAR), spectral diversity, terrain observation by progressive scan (TOPS).

Renewed Posteruptive Uplift Following the 2011–2012 Rhyolitic Eruption of Cordón Caulle (Southern Andes, Chile): Evidence for Transient Episodes of Magma Reservoir Recharge During 2012–2018

“…We use InSAR data from the COSMO‐SkyMED (CSK), RADARSAT‐2 (RS2), Sentinel‐1 (S1), and ALOS‐2 missions to produce time series and differential interferograms that span the complete inflation events (Figures , and S1–S3; Table ). These data sets were processed with standard algorithms described in detail in the supporting information (Agram et al, ; Chen and Zebker, ; Delgado et al, ; Farr et al, ; Fattahi et al, ; Fattahi and Amelung, ; Finnegan et al, ; Goldstein and Werner, ; Lopez‐Quiroz et al, ; Prats‐Iraola et al, ; Remy et al, ; Rosen et al, ; Samsonov, ; Sansosti et al, ; Yague‐Martinez et al, ; Zebker et al, ).. The differential interferograms calculated for every satellite orbit show ∼12 cm of uplift between June 2016 and February 2017 (Figures c to i), with a mean velocity of ∼23 cm/year (Figure ), in agreement with an independent ALOS‐2 ScanSAR time series (Euillades et al, ).…”

Ionospheric Correction of InSAR Time Series Analysis of C-band Sentinel-1 TOPS Data

“…More common examples in practical experience are found in the double-difference interferograms in the burst-overlap area after geometric coregistration, which sometimes show irregular patterns (e.g. [10], [11]).…”

The Multiple Aperture SAR Interferometry (MAI) Technique for the Detection of Large Ground Displacement Dynamics: An Overview

“…Let us first introduce the problem by considering two SLC IW images, which are usually acquired over several bursts in three overlapped swaths [79]. The fine co-registration of the two images represents one of the main issues of the Sentinel-1 (S-1) SAR data processing: to achieve this task, it is widely recognized that the azimuth co-registration of the SAR images has to be as accurate as possible to achieve a maximum error not exceeding 0,001 azimuth samples [78,80,81,133,134]. Usually, a conventional geometric co-registration step is performed preceding every SLC burst image.…”

“…This is achieved by combining LOS-projected deformation time-series obtained from different SAR platforms by imposing that the reconstructed 2-D (3-D) components of the ground deformation have a minimum acceleration. Noteworthy, the SD approaches are also currently used extensively to improve the performance of co-registration of the SAR images acquired with the novel Terrain Observation with Progressive Scans (TOPS) mode [77][78][79][80][81], which is the acquisition mode of the interferometric wide (IW) Sentinel-1 data [82]. Moreover, SD methods are used to estimate and correct atmospheric phase artefacts [83-87] that corrupt InSAR-driven ground deformation measurements.In this work, we first shortly summarize the fundamentals of InSAR technology.…”