Minimize Level-2 SYN

The Level-2 SYN product (SY_2_SYN) is produced by the Global Synergy Level-1/2 software and contains surface reflectance and aerosol parameters over land.

All measurement datasets are provided on the OLCI image grid, similar to the one included in the OLCI L1b product, consisting of N_COL_OLC x N_LINE_OLC pixels with:

  • N_COL_OLC = 4865 columns acquired
  • N_LINE_OLC = 60,000 lines acquired for one orbit

Some sub-sampled annotations and atmospheric datasets are provided on the OLCI tie-points grid.

The measurement data files included in this product provide:

  • Level-2 Surface Directional Reflectance (SDR) with their associated error estimates for the sun-reflective SLSTR channels (S1 to S6 for both nadir and oblique views) and for all OLCI channels, except for the oxygen absorption bands Oa14, Oa15, and the water vapour band Oa20
  • Level-2 aerosol optical thickness at 550 m (referenced as T550) with error estimates
  • Level-2 Angstrom coefficient (referenced as A550).

Several associated variables are also provided in annotation data files.

  • Aerosol Model Index Number (AMIN). This value is an integer number in the table of 40 aerosol models used for the atmospheric correction. A zero value indicates missing data.
  • Status flag computed by SYN Level-2 processing providing information about cloud, snow or land presence.
  • Flags corresponding to OLCI quality and classifications flags and to SLSTR exception summary and confidence flags.
  • DEM-corrected latitude, longitude and altitude.
  • OLCI time stamps.
  • Solar and viewing azimuth/zenith angles for each OLCI sub-sampled tie-point.
  • Some geophysical atmospheric data (derived from ECMWF files) such as the mean sea level pressure, the total column ozone and water vapour.
Variables Description Units Input Bands
SDR Atmospherically corrected surface directional
reflectance (also called Lambert equivalent
reflectance (LER) or bidirectional reflectance factor (BRF)). Each dataset includes a single SYN channel
dimensionless SLSTR S1 to S6 channels all OLCI channels except O14, 15 and O20
T550 Aerosol load, expressed in optical thickness
at a wavelength of 550 nm.
dimensionless SLSTR S1 to S6 channels all OLCI channels except O14, 15 and O20
A550 Estimated Angstrom exponent at a reference waveband of 550 nm. dimensionless SLSTR S1 to S6 channels all OLCI channels except O14, 15 and O20

Table 1: Description of Level-2 SYN product