The OLCI Level-2 product is composed of four packets, all available to the user depending on processing parameters.

• OL_2_WFR includes full resolution water and atmosphere geophysical parameters.
• OL_2_LFR includes full resolution land and atmosphere geophysical parameters.
• OL_2_WRR and OL_2_FRR include the same parameters but are computed at reduced resolution.

Each is composed of an information package map, also called a manifest, and several measurement and annotation data files.

The manifest file is written in XML and contains general information concerning the product and processing. The measurement and annotation data files are written in netCDF 4 format and include dimensions, variables and associated attributes.

The OL_2_WFR and OL_2_WRR packages include 24 measurement data files and seven annotations data files. The measurement files include 16 files containing water-leaving reflectances and their error estimates for all bands, except those dedicated to measurement of atmospheric gas (Oa13 to Oa15, Oa19 to Oa20). These files are produced on the product grid.

The other measurement files provide several marine and inland water products and associated error estimates:

• OC4Me Chlorophyll concentration
• neural net Chlorophyll concentration
• neural net total suspended matter concentration
• transparency products (Diffuse Attenuation coefficient)
• neural net water-inherent optical properties
• photosynthetically active radiation
• aerosol over water
• integrated water vapour over water.

The annotation files are similar to those included in OL_1_EFR and OL_1_ERR except the quality flags file is renamed "WQSF" (Water Quality and Science Flags).

The OL_2_LFR and OL_2_LRR packages include three measurement data files and eight annotation data files. The measurement files provide the OLCI Global Vegetation Index (OGVI), the OLCI Terrestrial Chlorophyll Index (OTCI) and the Integrated Water Vapour (IWV) column. Each parameter is associated with error estimates and computed on the product grid.

The annotations files are similar to the ones included in OL_1_EFR and OL_1_ERR, but:

• the quality flag file is renamed "LQSF" (Land Quality and Science Flags)
• one new annotation flag provides the rectified reflectance for the band Oa10 (named RC681) and for the band Oa17 (named RC865) and their error estimates.

The Level-2 Land Product Data Format Specification document contains more detailed information.  

OLCI Processing Baseline Timeline

Figure 1: OLCI Processing Baseline Timeline

OLCI Level-1 and Level-2 Processing Baseline

Table 1: OLCI L1 and L2 Processing Baseline

Processing Baseline 2.29 – March 2018

Introduction of a self-sending Radiometric Model (including a long-term instrument sensitivity evolution term) to OLCI radiometric calibration.

Processing Baseline 2.23 – Oct/Nov 2017

• The OLCI Radiometric Model, including a long-term instrument sensitivity evolution term, has been revised on the basis of an extended Radiometric Calibration dataset now being available, and now accounts for the ageing of the radiometric diffuser.
• The configuration of the Dark Correction has been revised to minimize horizontal striping that can appear over dark surfaces.
• Dark Offset correction tables are now built after filtering of High Energy Particles from Radiometric Calibration data, avoiding an occurrence of vertical striping in Earth Observation data.

Processing Baseline 2.16 – March 2017

• The behaviour of the H2O transmittance function to average input reflectances across a sliding window has been extended to reflectances over inland waters.
• Over bright surfaces, the OLCI L2 OGVI parameter has been set to 0 instead of previously NaN (Not a Number).