Minimize Processing Overview

At Level-1B, the OLCI instrument provides radiance measurements of the Earth's surface in the visible and near infra-red spectral domain in 21 spectral channels. These measurements are accurately calibrated TOA radiances, annotated with geo-referencing data and observation geometry parameters. Level-2 data processing aims to derive geophysical products through three main steps:

Ocean processing and land processing provide the expected geophysical properties corresponding to the surface types.

The pre-processing step aims to convert Level-1 TOA radiance into reflectance, which is a more relevant parameter for geophysical properties. This step is followed by a correction for gaseous absorption, pixel classification (in particular, water/land/cloud), instrumental correction for the smile effect (variation of the observed wavelength across the field of view) and retrieval of the total column water vapour content. After having eliminated cloudy pixels, according to the nature of the pixel (water/land), the OLCI Level-2 is organised into two independent processes:

  • water branch, consisting of a glint estimation and correction, a specific case two water reflectance estimation (in the NIR spectral range), aerosol identification and atmospheric correction allowing derivation of ocean colour and the final associated products
  • land branch, using two independent modules (the Global Vegetation Index and the Terrestrial Chlorophyll Index).

 

OLCI Level-2 Processing Top Level Breakdown