5.6 Overall quality of LSA SAF Vegetation Products

The overall quality of the LSA SAF vegetation products depends on the pixels location:

  • regions with large view zenith angles (e.g., North of Europe, South America) are expected to have larger errors (next Figure).

    SZA

    This is mainly the case of Europe during wintertime as a combination of multiple effects, such as:

    • low illumination and high observation angles;
    • higher anisotropy;
    • higher cloud occurrence;
    • larger shadows or traces of snow cover;
  • the African continent and the Mediterranean Basin are consolidated areas with optimal geometry of acquisition.

The spatial distribution of the mean FVC uncertainty along the year 2007 is depicted in next Figure:

Overall_quality_VEGA

The fraction of valid pixels (i.e. processed with reliability) for FVC over SAfr and NAfr zones is nearly 100% through the whole year. This is partly because products benefit from the high temporal sampling of the SEVIRI data, guaranteeing a high rate of cloud-free radiances per pixel.

The Europe and SAme continental zones present generally a decreased accuracy.