UC San Diego

A key element in the preparation for NISAR's launch (see Section 1.2) in 2023 is developing a methodology for validating NISAR-estimated displacements against GNSS displacements. In collaboration with the NISAR Solid Earth Science team I developed a Jupyter notebook workflow to download and generate timeseries of Sentinel-1 interferograms and GNSS daily solutions, project their displacements into radar line-of-sight (LOS), and derive velocity trends for each GNSS station in the given study site region and its collocated InSAR pixel. These velocity trends are then compared to asses the agreement of Interferometric SAR (InSAR) with GNSS. The effect of varying the following parameters were investigated: the GNSS station velocity approximation model, the reference station selected, various applied InSAR corrections, and the number of InSAR pixels averaged to form the InSAR collocated velocity. Analysis was conducted at two study sites, the Mojave Desert in California and a section of the Central Valley in California. The Mojave study site did not meet the validation requirement set by the NISAR team while the Central Valley did. Another key element of this project is providing future users with a clear and simple workflow to compare GNSS and InSAR data. The workflow discussed in this thesis has been handed off to the Solid Earth Science team to maintain and improve the user accessibility by moving the workflow into a cloud based environment.