Minimize Radiometric Calibration Mode

The radiometric calibration mode product consists of the dark offset and gain coefficients that shall be used to update the OLCI radiometric calibration Auxiliary Data File (ADF) used in Earth observation mode.

This product, OL_1_RAC, which is not available to the user, includes one measurement file and one annotation file, described below. The metadata information is gathered in a SENTINEL-SAFE product manifest.

The measurement file, radiometric_coef.nc, includes the dark offset and gain coefficients and is described in the following table. Only the main variables and their dimensions are reported, not their associated attributes.

 

Element name Description Dimension
Specific Dimensions
detectors Number of instrument detectors per frame (covering the five cameras). 1
bands Number of OLCI bands, excluding the smear band. 1
bands_total Number of OLCI bands, including the smear band. 1
dark_pixels Number of dark pixels for the five OLCI cameras. 1
blank_pixels Number of blank pixels for the five OLCI cameras. 1
Included Variables
dark_offset_coefficients Dark offset coefficients for all pixels. bands_total
detectors
dark_current_coefficients Dark offset coefficients for all pixels. bands_total
detectors
gain_coefficients Dark offset coefficients for all pixels. bands
detectors
shutter_mean_dark_pixels_time Time average of the dark pixels of the five cameras at the 21 nominal bands plus the smear band, all acquired in shutter position. bands_total
dark_pixels
shutter_mean_blank_pixels_time Time average of the blank pixels of the five cameras at the 21 nominal bands plus the smear band, all acquired in shutter position. bands_total
blank_pixels
diffuser_mean_dark_pixels_time Time average of the dark pixels of the five cameras at the 21 nominal bands plus the smear band, all acquired in diffuser position. bands_total
dark_pixels
diffuser_mean_blank_pixels_time Time average of the blank pixels of the five cameras at the 21 nominal bands plus the smear band, all acquired in diffuser position. bands_total
blank_pixels


The coefficients annotation file, RC_annotation.nc, contains:

  • quality information for each instrument detector, indicating if the percentage of valid pixels used in the time average of the dark offset coefficients computation is below a specific threshold and if the percentage of valid pixels used in the time average of the gain coefficients computation, is below another specific threshold
  • telemetry statistics providing the minimum, maximum and mean values of measured temperatures for each sub-sequence of the calibration sequence (i.e. while the Calibration Mechanism (CM) is in shutter position, or while it is in diffuser position).