Level-0 processing aims to generate Level-0 products, i.e. time-sorted and annotated data from Instrument Source Packets (ISPs). Level-0 products are internal products and are not available to Sentinel-3 users.
The first part of the process involves unpacking the ISPs, performing a quality check and appending annotation data to them. Once the input raw data files are read, all necessary data are extracted and parsed. The ISPs are sorted and checked for missing and duplicated packet numbering.
The final part of the process is Level-0 product generation. Several quality flags are computed and included in the associated metadata and the raw data, time-sorted and annotated are included in the Level-0 package.