A new aerosol remote sensing by moderate resolution imagers with near ultra-violet channels

Abstract:

The GOSAT satellite (Ibuki) is the first satellite for retrieving the column CO2 (XCO2) and CH4 (XCH4) with its shortwave Fourier Transform Spectrometer (FTS). In the retrieval algorithm, a correction of the path radiance effect of aerosol scattering/absorption is important to reduce the error in the gaseous absorption. For this purpose, the Cloud and Aerosol Imager (CAI) has been deployed to provide the aerosol information with its five bands including a unique 380nm band with 500m FOV. This band was also installed in the GLobal Imager (GLI) aboard the ADEOS-II satellite in 1990s. At this wavelength the surface reflectance is very small for improved aerosol remote sensing over arid land surfaces of high reflectance. We like to discuss new remote sensing algorithms with use of this NUV band and also a new formulation of multi-wavelength and multi-pixel remote sensing. We found that the new method significantly stabilize the inversion problem, even with only five wavelengths, to obtain both the aerosol optical thickness and single scattering albedo over land area through maximum use of the land surface heterogeneity of the moderate resolution imagers with FOV of 500m to 1km. We also like to discuss a new design of the 2nd CAI (CAI-2) aboard the GOSAT follow-on satellite (GOSAT-2) planned to be launched in 2017. This CAI-2 imager will carry 10 wavelengths including 340nm and 380nm and with two viewing geometries of tilt angles of -20 and +20 degrees along the track to avoid the sun-glitter in the ocean. We like to discuss how the capability of aerosol remote sensing is enhanced with this new design.