Let me to ask for the tools and methods for computing atmospheric correction in InSAR processing.
I am going to process about 30 tops sentinel-1 images for detecting the earth surface displacement and need to remove atmospheric effect from computed displacements. I couldn’t find this way in the SNAP software.
Please help me for computing this correction.
You might use TRAIN (TRAIN - Toolbox for Reducing Atmospheric InSAR Noise) for removing atmospheric effect from interferograms. But you first have to convert your SANP output format to TRAIN format. Below is the TRAIN discussion group link which might be help you.
For example, if you want to compute a single interferogram after an Earthquake or volcanic eruption, where the displacement is much higher than the normal atmospheric phase screen, you could avoid to do any atmospheric correction and consider that you are only measuring deformation (but there your assumption is that deformation>> atmosphere )
For SBAS, they normally estimate the APS of each single image by mathematical approaches, and they are normally well calculated, when the number of images where each single image is involved is relatively high (> 6/7 ifgs).
For PSI the only APS which can be well estimated is the one correspondent to the master image, and hence all APS for the slaves will be on your results. You should be at least aware of that. You can always remove it or not (depends on specific application) but you should know that the slaves APS is still there. Methods are many, you can just look around in literature. My suggestion is to use TRAIN from Dr. D.Bekaert, a very good friend that did a very nice work for his PhD creating this Tool for Reducing Atmosphere InSAR Noise (https://github.com/dbekaert/TRAIN) that is nicely working with StaMPS.
No installation needed. Just to add the configuration bash file to your .bashrc as you do with StaMPS.
Or at least this is what I remember as TRAIN is mainly matlab scripts called within StaMPS (sometimes) or directly from TRAIN scripts.
to get into the StaMPS matlab processing you need to use the stamps export function from SNAP or use the python wrapper from the snap2stamps package. The function will generate the correct files and folder structure for you to use in StaMPS and later in TRAIN. Have you read the blog i have send you, this should guide you nicely?
I am currently doing DInSAR for 2 months already. I haven’t started learning PSI/SBAS using StaMPS (because of my coursework load).
I just want to ask a detailed step-by-step procedure in SNAP on how to do atmospheric correction for one interferogram? If there is any straight forward process in SNAP without using a third-party app (eg TRAIN).
And when is it significant or not significant to consider the effects of the atmosphere?
Yes. I think it would be nice and convenient if atmospheric correction can be done directly through SNAP.
I’ve done a number of DInSAR analyses for 1 location in Korea considering ascending orbit (21 pairs) and descending orbit (22 pairs) and plotted displacement (LOS) over time. All estimations were generally uprising. My supervisor finds it strange because he thinks it should subsidence due to the possibility of groundwater drawdown during the tunneling activity.
I’ve also noticed that the selection of the reference point is very important for the generation of final displacement (LOS) map. With an initial reference point of my choice (eg along a road), I got subsidence. But when I changed it to another one (eg coincident with a building), I got uprising. I know that the choice of the reference point is also affected by the degree of coherence. For my reference point on a building, I am sure that all coherence values over time were closed to 1.0 (>0.95). For the point along the road, I didn’t record these values.
Now, it got into me that maybe the errors could be caused by the effect of the atmosphere.
Anyway, my apologies for sharing a long story here.
I think I will consider TRAIN for my DInSAR analysis to eliminate the atmospheric effects.