Hello
I’ve run the SNAP-StaMPS workflow for a masters project looking at subsidence on a golf course on a coastal peninsula. I’ve manged to run this successfully thanks to really clear and comprehensive guidance from Andreas Braun, Matthias Schlögl, Andrew Hooper and the ESA RUS training kit among others, for which many thanks. I am having difficulty though accepting the final velocity output.
The results seem to be robust to changing various parameters, I could not detect any unwrapping errors (although I'm not totally confident on what these look like), and the general of LOS range seems to be within a reasonable range for a non-seismic area (generally -20 to +10 mm/yr) when referenced to a GNSS station. All good so far.
However, when looking at the velocity output, two things strike me as odd.
A huge section of the interior (~100km2) seems to be subsiding at a rate of 2-5mm/yr, which is unexpected as this is a hard rock area with shallow soils. The analysis period (12 months) hopefully mitigate against any seasonal effects (but not interannual ones). There seems to be a gradual gradient from SW-NE which is particularly notable in the southwest of the image.
The maps shows lots of groupings 50-200m wide at the extreme ends of the range above. Closer inspection in the area of interest shows that a lot of these are on arable fields, with evidence of tracks showing movement of heavy machinery, but not always.
The ‘vdrop-do’ plots do not show any interferograms with strong influence on the output, and the results are similar for ascending and descending passes. I attach the velocity map and the ‘w-dm’ and ‘u-dm’ plots. I wonder though if anyone provide any thoughts on the following:
I also have a couple of more general questions:
Many thanks
Gavin