I need a Sentinel 1 scene for mangrove soil carbon and moisture estimation. The problem is that for my study area only SDV(VV+VH) pols are available at GRD-IW-High Resolution for the time period when sampling was done. I need the HH Pol as it has good interaction with horizontal targets such as land. I know mostly sentinel 1 is kept in SDV (transmitter-receiver mode ). Are there any other freely available SAR datasets like S1 having HH Pol? or any other suggestions are more than welcome regarding what should I do.
Unfortunately, Sentinel-1 is the only operating high resolution satellite which is made openly available. All others are either open but have already ended (ERS, ENVISAT, partly ALOS) or active but commercial.
HH polarization is only acquired over the arctic and some selected sites.
Still, Sentinel-1 VV is not entirely bad for soil moisture, as some studies show. But the upscaling to a high spatial resolution is rather complicated by now.
Thank you so much Andreas,
Please tell me little about dual pol polarimetric decomposition with sentinel 1 data in SNAP or PolSAR. I heard the process is very complicated and the software itself doesn’t have proper GUI. What options are available? HAα only? Give me some early guidance on it please
And about soil moisture whats is this SMOS application?
you can decompose dual-pol Sentinel-1 data but the results are not as good as if you had quad-pol data. You can check in the polarimetric tools which ones are available for dual-pol data
SMOS is a global mission to detect soil moisture. It is quit well calibrated and openly available, but only at a very coarse spatial resolution.
wow I see Free Man Durden and Yamaguchi too. out of them what will you suggest Andreas for soil moisture and Carbon? I remember the matrices we studied and it’s theory. Our professor emphasised remember you must have Quad Pol data.
I was reading earlier that the Radar of SMOS stopped working. It now only has the Radiometer. My study area is around 8000 Sq. Km will smos give some good results if we do a statistical correlation?
BTW are the polarimetric decomposition tools inside SNAP? As plugins?
actually, only these with “Dual Pol”, sorry for the misunderstanding. You can directly access them in the polarimetric menu.
However, I am not an expert on soil moisture, but it’s true that quad-pol data is much more helpful here because it allows to separate the different scattering mechanisms more properly.
Some datasets can be downloaded from NASA which use combinations of SMAP and Sentinel-1, but you have to find out if they are good enough for your use case.
Oops my bad 🤦 sorry!
Thank you for your precious time. Let me discuss these things with my supervisor.
And good luck with your study
I performed the HAalpha decomposition on sentinel 1 img. When I shared the results with my supervisor he replied this is wrong. How come two 2x2 matrix C11 and C22 return Entropy Anisotropy and Alpha. It should’ve Entropy and Alpha Only. My question is wether something is wrong with SNAP or what the three bands comprehend here?
I’m not sure how anisotropy is calculated in the dual-pol operator, but you find the source code here: https://github.com/senbox-org/s1tbx/blob/master/rstb/rstb-op-polarimetric-tools/src/main/java/org/csa/rstb/polarimetric/gpf/decompositions/HAlphaC2.java
I think I need a developer
@ABraun check this out. SNAP doesn’t have the Claude-Potteir Dual Pol as you suggested and the HAlpha Dual pol returns three bands. I am on latest version of SNAP all plugins updated.
you are right - it must have gone since the last update. I don’t see it any longer.
Should I downgrade? Or wait for the new update? Maybe that’ll have the fix for dual pol H-Alhpa decomposition. I hope. What do you think?
How much time will it take for the new updates and the fixes for these minor issues?
I am not sure there is an issue - did you read the corresponding help?
I don’t know - the Claude Pottier Dual Pol Decomposition was there 5 days ago.
@jun_lu Has this operator been changed with a last update?
Mine shows three bands for HAlhpa decomposition (Entropy Anisotropy and Alpha), and Cloude Pottier dual pol decomposition is not available at all. As @ABraun ascertained three threads above.
A post was split to a new topic: Problem installing sen-et
I think H-Alpha decomposition is the only available dual-pol decomposition. However, there is a “Cloude-Pottier” classification for dual-pol product