Creating a map of subsidence of the earth's surface

Hello! I just started learning about satellite zoning data processing. I had a problem creating a map of the earth’s subsidence. When I create a displacement map in the SNAP program for a period of 1 month, everything works out fine. I tried to make a displacement map for 2015-2016 and I got a difference in elevation of the surface of more than 100 meters. Is there a difference in the calculation methods?

More detail would helpful. When reporting a problem you need to provide enough detail so others can reproduce your calculation. In particular, what data did you use, what is your “region of interest”, and is the difference you report an average value, peak value, or something else?

This is my first experience with SNAP. I downloaded 2 data archives S1A_IW_SLC__1SDV_20150923T003557_20150923T003625_007835_00AEA7_EAE2 and S1A_IW_SLC__1SDV_20160917T003559_20160917T003626_013085_014C. In SNAP launched C1 TOPS Coreregistration, then Interferometric Formation, S1 TOPS Deburst, Subset, Multilooking, Goldstein Phase Filtering, Snaphu, Phase to Displacement, Range Doppler Terrain Correction. I got a displacement map where the values were very large. Image 1

Following the same principle, I did it for the data for 2018 with an interval of 2 weeks and I did it perfectly. Image 2. Territory Siberia, the city of Tomsk. I wanted to write an article about subsidence of the earth’s surface in the area of water supply wells. Orbits are loading normally. Can you please tell me if there is another algorithm of actions to get a more accurate displacement map in 2 years? Is the data calibration problem possible?

I was confused that the value for 2018 is in meters, and for 2015-2016 abs_phase. I couldn’t figure it out on my own. thank you!

if there is vegetation, you are stuck to image pairs of 6 to 12 days to keep temporal decorrelation as small as possible. But you can combine pairs of different times to create a time-series.
This can be done in the classic sense (as you did): Please check these slides (old, but correct in principal. The last part addresses combination of several image pairs)
or with the more advanced method of persistent scatterer interferometry (StaMPS - Detailled instructions)

Спасибо. Буду изучать слайды и пробовать.

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