The file naming convention for OLCI products (see this document for more details) is identified by the sequence of fields described here:

MMM_OL_L_TTTTTT_yyyymmddThhmmss_YYYYMMDDTHHMMSS_YYYYMMDDTHHMMSS_[instance ID]_GGG_[class ID].SEN3

• MMM is the mission ID:
  • S3A = SENTINEL-3A
  • S3B = SENTINEL-3B
  • S3_ = for both SENTINEL-3A and 3B
• OL is the data source/consumer (OL = OLCI)
• L is the processing level
  • "0" for Level-0
  • "1" for Level-1
  • "2" for Level-2
  • underscore "_" if processing level is not applicable.
• TTTTTT is the Data Type ID
  • Level-0 OLCI data:
    • "EFR___" = full resolution ISPs
    • "CR1___" = calibration with spectral relaxation
    • "CR0___" = calibration with no spectral relaxation.
  • Level-1 OLCI data:
    • "EFR___" = TOA radiances at full resolution
    • "ERR___" = TOA radiances at reduced resolution
    • "RAC___" = dark offset and gain coefficients from radiometric calibration
    • "SPC___" = wavelength characterisation from spectral calibration
    • "INS_AX" = instrument characterisation auxiliary data
    • "EFR_BW" = browse product derived from "EFR___"
    • "ERR_BW" = browse product derived from "ERR___".
  • Level-2 OLCI data:
    • "WFR___" = full resolution ocean colour, water and atmosphere parameters
    • "WRR___" = reduced resolution ocean colour, water and atmosphere parameters
    • "LFR___" = full resolution land colour and atmosphere parameters
    • "LRR___" = reduced resolution land colour and atmosphere parameters
    • "ATP_AX" = atmosphere parameters auxiliary data
    • "AER_AX" = aerosol climatology auxiliary data
    • "LAP_AX" = land aerosol parameter auxiliary data
    • "LVI_AX" = land vegetation index auxiliary data
    • "WFR_BW" = browse product derived from "WFR___"
    • "WRR_BW" = browse product derived from "WRR___"
    • "LFR_BW" = browse product derived from "LFR___"
    • "LRR_BW" = browse product derived from "LRR___".
• yyyymmddThhmmss is the sensing start time
• YYYYMMDDTHHMMSS is the sensing stop time
• YYYYMMDDTHHMMSS is the product creation date
• [instance ID] The field consists of 17 characters, either uppercase letters or digits or underscores "_".

The instance id fields include the following cases, applicable as indicated:

1. Instance ID for the instrument data products disseminated in "stripes":

Duration,"_", cycle number, "_", relative orbit number,"_", 4 underscores "_"
DDDD_CCC_LLL_____
2. Instance ID for the instrument data products  
disseminated in "frames":
Duration, "_", cycle number, "_", relative orbit number, "_", frame along track coordinate
DDDD_CCC_LLL_FFFF
3. Instance ID for the instrument data products disseminated in "tiles".
Two sub-cases are applicable:
a) tile covering the whole globe:
      "GLOBAL___________"
b) tile cut according to specific
geographical criteria:
Tile Identifier
ttttttttttttttttt
4. Instance ID for auxiliary data:
            17 underscores "_" 

• GGG identifies the centre which generated the file
• [class ID] identifies the class ID for instrument data products with conventional sequence "P_XX_NNN" where:
  • P indicates the platform (O for operational, F for reference, D for development, R for reprocessing)
  • XX indicates the timeliness of the processing workflow (NR for NRT, ST for STC, NT for NTC)
  • NNN indicates the baseline collection or data usage.
• .SEN3 is the filename extension.

Example of filename:

S3A_OL_1_EFR____20160614T101206_20160614T101506_20160614T120248_0180_005_179_2339_SVL_O_NR_001.SEN3