General information: Monthly climatology photosynthetically available radiation in E.m^-2.d^-1 (mol photons per square meter and per day) derived from the SeaWiFS sensor. Processing information: PAR data is reprocessed using the NASA SeaDAS 6.4 software (Frouin et al., 2003). Description of observation methods/instruments: The approach is described by Frouin et al. (2003).The content of the atmosphere in terms of aerosols and clouds is inferred from the spectrum of top-of-atmosphere radiance collected by the sensor in space. In turn, the downwelling irradiance reaching the surface of the ocean is computed using plane parallel theory. Eventually, by integration spectrally and over time, PAR is expressed as a daily value. Quality/Accuracy/Calibration information: The approach and results are described by Frouin et al. (2003). PAR represents the radiation in the spectral domain of relevance for photosynthesis (400-700 nm), and is used in model of primary production. References: Frouin, R., Franz, B.A., Werdell, P.J.: The SeaWiFS PAR product. In "Algorithm updates for the fourth SeaWiFS data reprocessing", S.B. Hooker and E.R. Firestone (Eds.) NASA/ NASA Technical Memorandum, 2003-206892, 22: 46-50.