@simonf and I are going to reprocess Sentinel 1 GRD in Google Earth Engine to address some issues our users have brought up.
One issue is the low intensity border noise that appears in many if not all scenes.
E.g: S1A_EW_GRDM_1SSH_20170610T073136_20170610T073221_016968_01C3F8_6F21
Currently our processing graph for each scene is:
Read -> Apply-Orbit-File -> ThermalNoiseRemoval ->Calibration ->Terrain-Correction -> Write
We were thinking of using the GRD Border Noise Removal operator at the start of our chain, but it seems that it also sometimes removes valid low intensity pixels in the ocean. This might be OK if most if not all users want to mosaic images from the same region, however this may hurt others who rely on low intensity values for individual scenes.
I have observed that the border noise removal operation removes everything with a DN < 30 within the border margin specified. So in some cases the large amounts of ocean pixels may be removed as mentioned in other posts in this forum.
Furthermore the operation doesn’t always remove the border noise as seen in this post and based on personal experience.
I was wondering what approaches some people have to this problem and if users would prefer keeping the data intact and having to do their own border masking (which is possible in Earth Engine) vs having a standard algorithm applied to the entire collection.
Any input would be appreciated.
Thanks for your time,
Daniel Coelho