General information: Monthly mean absorption coefficient due to chromophoric dissolved organic matter and non-pigmented particles at 443nm in m^-1 derived from the MERIS sensor. Processing information: adg(443) data is reprocessed using SeaDAS 6.4 software and the QAA algorithm (Lee et al., 2002). Temporal characteristics: This dataset consists of standard monthly mean sea surface adg(443) maps at 2km resolution (L3 product). Description of observation methods/instruments: The remote sensing of 'Ocean Colour' represents a measure of the spectral variations in the light leaving the water surface, subsequently interpreted in terms of concentrations of optically-significant constituents in the water. The electromagnetic signal collected by the sensor on-board the satellite is largely determined by photons that have never reached the water surface, but have been backscattered within the atmosphere through multiple interactions between gas molecules and aerosols. After removing the atmospheric contribution, the water leaving radiance recorded at a given time by the satellite reflects the optical properties of the water which, in turn, mirrors a specific structure and biogeochemical composition of the marine waters. The satellite-derived reflectance at the air-sea interface is related to inherent optical properties of the water constituents including as adg(443). Quality/accuracy/calibration information: The calculation is based on a semi-analytical bio-optical algorithm. More details as well as validation results are given in Lee et al. (2002), IOCCG (2006) or Melin et al. (2007). References: Lee, Z.-P., Carder, K.L., Arnone, R.: Deriving inherent optical properties from water color: A multiband quasi-analytical algorithm for optically deep waters. Appl. Opt., 41, 5755-5772, 2002. IOOCG Report 5: Remote sensing of inherent optical properties: Fundamentals, tests of algorithms, and applications, Eds. Z.-P. Lee, 126pp., 2006. Mélin,F., Zibordi, G., Berthon, J.-F.: Assessment of satellite ocean color products at a coastal site. Remote Sens. Environ., 110, 192-215, 2007. Other contextual information: The product is stored in NetCDF data and available for download.