User Guides - Sentinel-3 SLSTR - Level-1b Product - Sentinel Online
The SLSTR Level-1B product gathers, for each view and for each channel, the full-resolution geolocated radiometric measurements.
For thermal IR and fire channels (labelled as S7 to S9 for TIR channels and F1, F2 for fire channels), the radiometric measurements are expressed in Top Of Atmosphere (TOA) brightness temperatures. In the case of visible / SWIR channels (labelled as S1 to S6), these measurements are expressed in TOA radiances.
The radiometric measurements are indexed according to the across track and along track direction:
- on a 1 km grid for brightness temperature for channels S7-S9 and F2
- on a 1km grid that is applicable to the F1 channel
- on a 0.5 km grid for radiances. In this case, two stripes are distinguished: stripe A for S1-S6 and stripe B for S4-S6.
There are essentially eight 'grids' due to the TIR 1km infrared 'i' grid, the 'f' grid specific to F1, and the two different 0.5km grids 'a', 'b'. Each of these is represented on the nadir and oblique views, making a total of eight.
The SLSTR Level-1B product also contains the following annotation data sets (ADSs):
- Quality - quality annotations per channel, such as estimates of detector noise measured at the VISCAL or black body calibration sources
- Flags - flags concerning cloud identification, surface classification and scan and flip mirror testing provided per grid
- Indices - arrays of indices to retrieve the position of each pixel in the instrument measurement frame provided per grid
- Cartesian - a file providing the Cartesian coordinates per grid
- Geodetic - geodetic coordinates associated with the radiometric measurements on each grid and to the tie-point grid defined for SLSTR
- Time - the timings of the pixels provided per grid for the nadir view only
- Met - meteorological annotations, provided once per product