Early phase analysis of OCTS radiance data for aerosol remote sensing

An analysis of ocean color temperature scanner [(OCTS) on board the advanced earth observation satellite (ADEOS)] spectral radiance data was performed for retrieving global distributions of Angstrom factor and exponent, which represent the aerosol optical thickness at a reference wavelength (500 nm in our study) and a spectral dependence of the optical thicknesses, respectively, over ocean. Determination of calibration constants for OCTS-received radiances and development of an efficient look-up table method for synthesizing the radiances are key issues for development of the present two-channel algorithm with use of channel 6 and 8 radiances of OCTS. This algorithm has been applied to Level-1B OCTS GAC data sets for producing three month (April, May, and June 1997) global distributions of Angstrom parameters. Geographical and seasonal distribution patterns of Angstrom parameters suggest that anthropogenic sulfate aerosols in mid-latitudes and biomass burning aerosols in the subtropical region are characterized by small particles having large Angstrom exponents, whereas mineral dust particles from subtropical arid regions are characterized by large particles having small Angstrom exponents. There was a fairly good agreement between satellite-retrieved values of Angstrom parameters and values obtained by sky radiometers located on coasts.