InSAR Validation Using Free GPS Data in Iceland

Worldwide network of GPS sites with free data
Location of the GPS station in south-western Iceland

GPS Ground Truth

First let’s go over the the ground truth data of the NYLA station. The ground truth is located at the coordinates 63.974, -22.738 degrees (Latitude, Longitude). Based on Google Maps imagery the station is located in an open field with no nearby structures and the terrain appears to be flat.

Figure taken from the NYLA station page
Image showing full range of GPS data with reference date in 2017. Velocity is -4.51 mm per year.
Image showing filtered range of GPS date with reference date still in 2017.

Distributed Scatterer Interferometry (MintPy)

Miami INsar Time-series software in PYthon (MintPy) is a relatively new timeseries algorithm based on the small baseline method for InSAR. It is based on the work by Yunjun, Z., Fattahi, H., and Amelung, F. (2019). In this quick analysis we are just using the default parameters. I prefer working with this algorithm because it is actively maintained and uses pure Python code that works in all operating systems.

MintPy result showing Southern Peninsula in Iceland. GPS site is red triangle in the west.
MintPy SBAS output for NYLA station

Persistant Scatterer Interferometry (StaMPS)

The Stanford Method for Persistant Scatterer (StamPS) is an old but popular timeseries algorithm in the InSAR community. It was written by Hooper et al. (2006). The drawback with this algorithm is that the barrier of entry is high since it requires the user to be familiar with Linux, terminal commands, a paid MATLAB license, and some programming skills because the algorithm is no longer maintained by its original author. Bug fixes that have been identified by the community have to be fixed by the user.

StaMPS output on a webmap
StaMPS result

Comparing the Results

GPS: -0.034 mm per year with a standard error of ±0.001 mm

Links to the Software I used

MintPy

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Panji Brotoisworo

Panji Brotoisworo

Researcher working on geospatial sciences and general programming