Forest fire. Credit: gilitukha

Sentinel-3 NRT Level 2 aerosol product Collection 2


Forest fire. Credit: gilitukha
Forest fire. Credit: gilitukha

Collection 2 of the Optimised Copernicus Sentinel-3 (CS3) NRT Level 2 (L2) aerosol product will be released on 28 October 2021.

Last Updated

26 September 2023

Published on

14 October 2021

This product is produced by the reference 'Optimised Simultaneous Surface Aerosol Retrieval' (OSSAR-CS3) processor upgraded as version 3 in the EUMETSAT operational S3 ground segment. In the long term, EUMETSAT intends to establish an algorithm baseline resilient to any dual-view direction from space-borne sensors.

Key evolutions to land surfaces/continents implemented in Collection 2

  • A new optical cloud mask algorithm.
  • A consolidated estimation of the first guess land vegetation surface reflectance and its implementation within the aerosol retrieval scheme, regardless the land cover type and the dual-view geometry configuration.
  • Enhanced quality flagging.

Over land surfaces, these evolutions bring major quality improvements to Aerosol Optical Depth retrieval (e.g. strong bias reduction, lower amount of cloud contamination). As a result, the scientific maturity and quality label of the product over lands has been upgraded from Demonstrational (Collection 1) to Preliminary Operational (Collection 2), thus, now aligned with over oceans. Figure 1 illustrates the benefits with the 2021 Siberian wildfires.

Figure 1: Example of comparison of Sentinel-3 SLSTR data with Suomi-NPP VIIRS data

Other changes are the provision of a series of new parameters in the output netCDF product:

  • Over Lands: AOD (550nm) uncertainty, Angstrom Coefficient (550–865nm), Dust AOD, Absorbing AOD, Fine Mode AOD.
  • Merged Land/Ocean AOD (550nm).
  • Scattering angles for both nadir and oblique views, per individual L2 aerosol pixel.

Over oceans, the algorithm remains strictly similar between Collections 1 and 2.

Further information

We invite users to provide feedback on the ATBD and PVR v1 documents, as well as on the Collection 2 data. This will be used as part of v2, and in the preparation of the future Collection 3, planned for 2022.

For more information contact our User Service Helpdesk.