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[Abstract] A portable multispectral polarimeter named PSR-1000, which has the same observing bands as ADEOS/POLDER, has been introduced since 1996. PSR-1000 is designed to measure direct solar radiation and diffuse sky radiation. First of all, a calibration of the PSR-1000 was done based on Langley plot method involving gaseous absorption from October 27 to November 2 in 1997 at Mt. Mauna Kea in Hawaii Island. Then the measurements of polarization and optical thickness of aerosols with the PSR-1000 were undertaken over the ocean around Shikoku Island of Japan in 1997, 1998 and 1999. It is found that the relationship in respect of wavelength dependency between the observed optical thickness and degree of polarization is classified into two groups. The measurements are available to retrieve the optical characteristics of aerosols, e.g., refractive index, size distribution parameters, based on light scattering simulations in the polarization field. From the retrieved results, it can be seen that; (1) heterogeneous particles are good a candidate for our aerosols, (2) contamination rate of water-soluble inclusions to the oceanic matrix of heterogeneous model aerosol decreases from inland to the open sea.

The GOSAT satellite has been designed for retrieving the carbon dioxide amount in the atmosphere by a Fourier transform spectro-radiometer (TANSO-FTS). It is, however, known that FTS-observed radiances in the near-infrared spectral region are heavily contaminated by a solar radiation component scattered by atmospheric aerosols, which is known as "path radiance". In order to correct the path radiance, a multispectral visible-near infrared imager (TANSO-CAI) will be on board the GOSAT satellite to acquire the aerosol and cloud information that is indispensable for correcting the atmospheric path radiance to improve the carbon dioxide remote sensing by FTS. In this article, we study aerosol retrieval algorithms and cloud screening algorithms using the four channel radiances of CAI. We also present the methodology for vicarious calibration and validation for the CAI remote sensing, intercomparison of CAI-retrieved aerosol products with those from other satellite-borne sensors, and the data fusion strategy of satellite-measured and model-simulated aerosol properties.