Minimize SLSTR Level 1 Processing - Observation Mode Parameters
Eight different auxiliary files are used during SLSTR Level-1 processing, in Observation and Joint mode:
  • The SLSTR Level-1 Ancillary data file defines the sizes and offsets of the SLSTR ancillary data variables in the ancillary ISP, and lists the calibration functions and parameters that should be applied to each variable. It will be determined during the ground characterisation of the instrument and will be fixed before launch. Additional entries define bit masks and validation limits for the raw data and surveillance limits for calibrated data.
  • The SLSTR Level-1 Visible and Shortwave Infra-Red Characterisation data files define non-linearity correction tables and general calibration parameters for each visible and shortwave infra-red channel. These data are generated during ground calibration of the instrument. There are two netCDF files for each of the S1, S2 and S3 channels, one each for the nadir and oblique views, and four netCDF files for each of the S4, S5, S6 channels, representing the permutations of the two views and the A stripe and B stripe detector groupings.
  • The SLSTR Level-1 Thermal Infra-Red Characterisation data file defines radiance-to-temperature Look-Up Tables (LUTs) and non-linearity correction tables, as well as general calibration parameters for the thermal infra-red channels. These data are generated during ground calibration of the instrument. There are two netCDF files for each of the S7, S8, S9, F1 and F2 channels, one each for the nadir and oblique views.
  • The SLSTR Level-1 VISCAL data file contains summary visible and shortwave infra-red calibration information derived from the VISCAL solar illumination period located within a previous product, typically for the orbit immediately preceding the current product. Note that this file is produced during calibration of the SLSTR Level-1 processor
  • The SLSTR Level-1 Vicarious Calibration data file comprises a table of scaling factors for each VIS-SWIR band (S1-S6) that allows correction for long-term drift. There is a drift correction factor provided for each day of the SENTINEL-3 mission. The default values for the scaling factors shall be set to 1, i.e. no correction to be applied to the data.
  • The SLSTR Level-1 Geometry data file defines the instrument geometry parameters used in geolocation processing. The transformation matrix between the satellite reference frame and the instrument frame is computed using these parameters (cone angle for each scan, scan inclination for nadir scan) and the geographical position of each pixel is determined.
  • The SLSTR Level-1 Geometry Calibration data file provides the quaternions characterising the biases and thermo-elastic deformation model for nadir and oblique views, defined as rotation from instrument to SC frames. Quaternions are provided for each view, each Julian day and each on-orbit position angle. They are divided into four components, with the first representing the real part of these thermo-elastic deformations.
  • The SLSTR Level-1 Cloud LUT data file provides parameters used by the cloud-clearing algorithms. The data are split into several groups, each dedicated to a specific cloud test and providing specific parameters and thresholds. This ADF will be updated during coming evolutions thanks to simulated SLSTR L1 data and further analysis.
  • A specific ADF providing relevant data for Stray Light correction will be defined during coming evolutions.