Products Description


Merging methods


Input data sensors

Product User Guide


GlobColour Products Description

Merging Methods

At the start of the GlobColour project three merging techniques were identified as the basis for further testing (see the PUG for further details):

  • Simple averaging (AV);

  • Weighted averaging (AVW) with weightings based on the sensor/product characterisation;

  • GSM model based on Maritorena and Siegel (2005, Remote Sensing of Environment) paper.

At the end of phase two the following recommendations were made (see the PVAR for further details):
  • Fully normalized water-leaving radiances (Lxxx): The statistics were slightly better when using the weighted average than the simple averaging, so the weighted averaging was chosen.

  • Chlorophyll (CHL1): GSM provided the best fit to in-situ chlorophyll and had the added advantages of providing other products and the ability to calculate pixel-by-pixel error bars. The linked products, also output from the GSM model, are Coloured dissolved and detrital organic materials (CDM) and Particulate back-scattering coefficient (bbp).

The remaining products are then derived as follows (see the PUG for further details):
  • The diffuse attenuation coefficient at 490 nm, Kd(490), is derived from the merged chlorophyll.

  • The "excess of radiance" at 555 nm, EL555, is derived from the merged chlorophyll and the merged fully normalized water-leaving radiances.

  • The aerosol optical thickness at 865 nm, T865, is derived by simple averaging of the aerosol optical thickness provided by individual sensors at the same wavelength.

  • Total Suspended Matter (TSM), CDM and Case II Chlorophyll (CHL2) are also products from just the MERIS data.

  • Cloud Fraction (CF) based on classification and statistical methods.

The European Service for Ocean Colour - GlobColour is an ESA Data User Element Project