Hi. I am processing some TerraSAR-X images using SNAP over an area of ocean north of New Zealand. We chose the Wide ScanSAR mode in MGD format because we wanted to cover a large spatial region. I have applied radiometric calibration to sigma0 but the images are very noisy compared to other SAR sensors that are using similar modes/resolutions. For example, see the attached image where you can see lots of noise. There is also a strange spatial structure despite this being an area of open open with no land or structures to reflect the radar signals (caused by weather or wave conditions?).
I have tried to apply speckle filters and additional multi-looking to the image, but this doesn’t help. After some digging around online, I found some old presentation slides from 2008 titled “TerraSAR-X Products – Tips and Tricks” which talked about these noise patterns in low backscatter areas which are typical for ScanSAR, but I wasn’t able to find any further information.
Does anyone on this forum have experience processing TerraSAR-X images using SNAP that may have some advice? My usual processing chain for processing (non-Sentinel) SAR images in ScanSAR mode over flat ocean is very simple. I just apply radiometric calibration to sigma0 and then geocoding using the Ellipsoid Correction.