Radiance to Reflectance Conversion

This process aims to extract the input Level-1B data and convert the included radiance into reflectance through three main steps.

  1. Pre-processing for geometry and meteorological parameters: This step is carried out to derive geometry and meteorological parameters (pressure, wind) at each pixel, including invalid ones, from those provided at each tie-point of the Level-1B annotation product.
  2. Level-1B pixel classification screening. Level-2 pixel identification starts with reading of the INVALID flag of the Level-1B product. If it is set to TRUE, no further processing of the current pixel is performed, the Level-2 product shall contain fixed values for all geophysical products, with the INVALID flag set, and the next pixel is examined. Otherwise, processing of the current pixel is pursued.
  3. Pixel extraction and reflectance conversion. If the Level-1B pixel is not flagged INVALID, the other Level-1B flags and the top of atmosphere radiances at all bands are extracted from the Level-1B product. Radiances are converted to reflectances using the sun zenith angle cosine interpolated at the pixel and the sun spectral flux, read from the Level-1B product annotations.

Note that this process also includes preliminary processing applied to annotation and measurements data sets (interpolation of annotations from the tie-points grid to the pixel grid and radiance to reflectance conversion respectively).

Functional Block Diagram of Radiances Into Reflectances Conversion


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