You should apply thermal noise removal, calibration and slice assembly. Radiometric normalisation should not do anything since there’s practically no topography over the ocean.
thanks both of you for the replies - looking through the help i think ‘slice assembly’ might be what i want and not mosaic afterall.
Should i apply the thermal noise removal? i thought i saw in a previous post that it was not necessary over water. or is it used if there is any land in the scene.
If these are S-1 Slice products then it would be better if you use the Slice Assembly. The mosaic is intended for terrain corrected data to blend composites and you end up with a nice image but it is no longer a ‘product’ with corresponding metadata.
Slice assembly on the other hand will update the metadata and it remains a Sentinel-1 product which you may continue to process like any other S-1 product.