MERIS Value Added Products

The following Level 2 products are generated by the MERIS-VA processing chain:
Calculated with regional algorithms for the North Sea, Baltic Sea and Lake Constance:

• Chlorophyll-a concentration (ATBD RTM algorithm, ATBD PCI algorithm)
• Total suspended matter concentration (ATBD RTM algorithm, ATBD PCI algorithm)
• Yellow substance absorption (ATBD RTM algorithm, ATBD PCI algorithm)
• Coarse and fine portion of the aerosol over coastal waters (ATBD)
• AVHRR compatible vegetation index (ATBD)
• Cloud top pressure, cloud albedo and cloud optical thickness (ATBD CTP, ATBD CACO)
• Total column water vapour amount (ATBD)

Level 3 products as arithmetic mean, MLE estimator or min/max values of the above Level 2 products are generated by a generic, configurable Level 3 processor (ATBD). In addition, the following specific Level 3 products can be generated:

• Land Cover Classification index (ATBD)
• Cloud statitistics (vertical distribution of cloud property and water vapour statistics) (ATBD)

Data Format (IODD)

All MERIS-VA primary products are written in the Hierarchical Data Format 5 (HDF-5). Each product file contains groups for scene data, geolocation (tie-point data), and metadata (global attributes). The scene data group consists of one or more sets of geophysical parameter data, along with quality flags and quality measurements for each MERIS pixel. The structure of both L2 and L3 products is identical and compatible with BEAM.

MERIS-VA primary product file		Scene data group of an RWC_RTM L2 product file

The quality flags reflect special conditions or exceptions occurred during the calculation of geophysical parameters. A subset of the standard ESA Level 1 and 2 MERIS products is always provided. The optional quality data sets are used to assess the quality of the calculated geophysical parameters, for instance the residual sum of squares of observed and predicted radiances assuming the calculated geophysical parameters are correct. A MERIS-VA L2 product file can contain multiple geophysical parameter data sets that can share the same quality data set.