Frenquently Asked Questions

What is MEGS81 processor?

MEGS is MERIS Ground Segment prototype processor. MEGS8.1 version is strictly equivalent to the IPF 6.04 (Instrument Processing Facility) operated since November 2011 at ESA Ground Stations (Kiruna and ESRIN) for the MERIS 3rd reprocessing, except for slight modifications in the Case 2 branch. For more details about MEGS, please browse through this ESA web page or ODESA forum.

What is SAABIO processor?

SAABIO is an alternative to MEGS8.1, i.e. 3rd MERIS reprocessing? It differs from MEGS_81 on the following points:
  • A semi-analytical Bright Pixel Atmospheric Correction (BPAC) is implemented.
  • Case 2 Neural Net product (Chlorophyl_2, CDM and SPM) are replaced by GSM model outputs (chl_gsm, adg_443_gsm and bbp_443_gsm).
All nominal MERIS level 2 products (alpha, AOT865, chlorophyll_1, NRRS … ) will differ from one MEGS8.1 to SAABIO since alternative BPAC will affect the atmospheric correction chain. For detailed description of SAABIO, please refer to SAABIO Documentation.

How can I implement a level 2 algorithm on MERIS images?

MERIS level 1 product available on Kalicotier platform can be processed with ODESA software. ODESA software provides level2 processing source codes. Any algorithm developed in C, C++ or fortran can be implemented in the processing chain. ODESA software can be downloaded for ODESA web page (link to A quick start guide and a detailed tutorial can be found on the same webpage. For any question, please post on ODESA forum.

Where can I get support for kalicotier products usage?

  • For any question related to MERIS products, please post on ODESA forum .
  • For any issue about kalicotier web page please email to the kalicotier team (
What are the differences between MEGS_8.1 and SAABIO processor?

Schematic of MEGS_8.1 and SAABIO level 2 processing chain are available here: (Fr), (Eng)
For detailed description of MEGS _8.1, please refer to topic on the ODESA forum or the ESA documentation page.
For detailed description of SAABIO, please refer to SAABIO Documentation.
Four additional algorithms have been implemented in SAABIO processing chain in June 2014 to generate:
December 2014: five additional algorithms have been implemented in SAABIO and MEGS81 processing chain to generate:
  • Particulate Back-scattering coefficient at 5 wavelengths (bbp ; 412, 443, 490, 510 and 560nm)
  • Gamma, Spectral Slope of bbp
  • None water Absorption at 6 wavelengths (anw ; 412, 443, 490, 510, 560 and 670nm)
  • Colored Dissolved Organic Matter at 412nm (acdom412) - Loisel et al., 2014
  • Dissolved Organic Carbon (DOC)

What is the format of the Level 2 projected products released in December 2013?

The previous Level 2 products provided on satellite track grid have been replaced by level 2 products projected on a Plate-Carrée grid.
For details about the projection please download the Level 2 projection definition.
Level 1 data remain identical.

What are the products delivered by Kalicôtier?