Persistent Scatterer point offset in Northern Areas

Hi there,
When producing a Persistent Scatterer result for Northern areas (specifically Yellowknife in this case). There appears to be an offset between the location of the PS points and the surfaces in the basemap.

As you can see the points the would be scattering over the runway appear to have a ~200m offset. This trend was confirmed using a Sentinel-2 image aswell. The DEM input was the Copernicus 30m DEM.

The geometric accuracy of SAR is excellent and certainly much better than S-2. Something must have gone wrong at the map projection step of either your S-1 stack or the reference S-2 image. Are you using S-1 data?

Yes the data used in S1. The same processing chain has been used for many PS runs. This error only seems to occur in Northern Regions. This error was reproduced with the ASTER Dem in Northern Regions as well. It has been compared to multiple basemap images included S2.

Below is a screenshot of the same processing parameters overtop of Toronto Pearson Airport. Where no offset is occurring.

Do the ground features in the GRD backscatter output align with the PSI output over these areas?

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The GRD backscatter output does not seem to align with the PSI points but more closely aligns with the what is expected on the basemap

What are the map projections of the SAR outputs and the base map?

All layers are in EPSG:4326 - WGS 84

Same coordinate system - ok. Is there a shift between the SLC/GRD and the base map before any PS processing?

The relative position of a scatterer within a resolution cell causes an additional phase contribution in the observed phase, which needs to be accounted for in PSI processing. Please see this reference.

On the influence of sub-pixel position correction for PS localization accuracy and time series quality