Characterization of aerosols over ocean from POLDER/ADEOS-1

POLDER (POLarization and Directionality of the Earth's Reflectance) is a French instrument, launched in August 1996 onboard the Japanese sun-synchronous ADvanced Earth Satellite System (ADEOS). Data were acquired until the loss of the platform June 30th 1997. This paper describes information on the global distribution of tropospheric aerosol over the ocean derived from the POLDER instrument. The aerosol remote sensing algorithm yields the aerosol optical thickness at 0.865 mu m, tau and the Angstrom exponent, alpha, which allows the retrieval the aerosol sizes. Monthly synthesis of the global aerosol characteristics over the ocean are presented and described here for three months: November 1996, February, and May 1997. The major and most persistent feature is the Saharan dust outbreaks off West Africa. Biomass burning aerosols are observed during May off the western Mexican Coast and during November in Madagascar, Asian, Indonesian and eastern US pollution are also observed. For some of these areas; statistical distributions of tau and alpha and their spatial variability are discussed.