Minimize MERIS Products Availability - Level 2

 

The MERIS Level 2 are bio-geophical parameters for ocean, land and atmosphere. Binary flag information is added to further describe the pixels (all L1b flag plus parameter specific quality and additional processing detail information). On a tie point raster meteorological and geometrical information is included in the product. A detailed description of the MERIS Level 2 algorithms and products can be found in the MERIS Handbook (Level 2 section).
 
The FR and RR Level 2 products are made availabe to users throught the MERCI online system, ftp and through EOLI-SA.
 
Before release of the products to users the data were quality controlled. Black-listed products are totally corrupt and not released. Segregated products contain errors are excluded from normal distribution to avoid problems when users perform automated bulk processing. The segregated products are available to users on request.

 

The segregated list for Level 2 is the same as for Level 1. Checks have been carried to out confirm that all products segregated under L1b are also erroneuous in Level 2, and no further corrupted Level 2 products were found. Please refer to Level 1b page on the information of the segregated files.

 

Further users should be aware of a problem with the Case 2 products in the currently released MERIS Level products (RR and FR):

 

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Case II Waters Advisory Note
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Case II waters are complex waters found within inter-coastal zones, which are influenced by a multitude of parameters. As a result, the optical properties of such waters are highly variable and are controlled by three independent components:
  • Phytoplankton and their associated debris,
  • Dissolved organic matters of terrigenous origin, known variously as yellow substance, Gelbstoff, Gilvin or CDOM (coloured dissolved organic matter),
  • Mineral particles and various suspended sediments.
The changes made to the Case II waters algorithm throughout the 3rd Reprocessing are detailed within the Case 2 Waters ATBD.
 
Case II waters require the separation of different optical components, currently achieved via a series of BEAM plug-ins, designated to the atmospheric correction and retrieval of oceanic constituents. Read more here.
 
The MERIS QWG has found that these algorithms are not reliable following user reported problems with the bands associated with Case II waters, such as the Algal_2 band. In particular, a discrepancy has been observed within the unrealistic correlation between optical chlorophyll values and acquisition seasonality. Therefore, it has been proposed that the algorithms associated Case II Waters be revised throughout 4th Reprocessing activities.