Radiometric characteristics of the sensors on board MOS-1 were assessed using pre-launch data and simulations taking into account sea surface conditions, influences due to Sun glitter, atmospheric effects, etc. Consequently, it was found that the following are noticeable: (1) MIN/MAX radiances and signal-to-noise ratios at the radiances of MESSR are almost the same as those of Landsat MSS. (2) A 7 per cent influence caused by Sun glitter, in terms of the equivalent glitter reflectivity, is estimated for the worst case. This would occur at the summer solstice, at 11 00 hours Local Mean Time and with an ocean wind speed of 7 m/s, (3) The percentage ratios of reflectance radiance to path radiance for MESSR-1 to -4 are, respectively, 60·08, 95·29, 130·70 and 267·63 per cent. These ratios would result from a ground cover target with minimum albedo in the summer under hazy atmospheric conditions. (4) A 9 per cent influence caused by Sun glitter, in terms of the equivalent glitter reflectivity, is estimated for VTIR-1 in the worst case. This would occur at the summer solstice, at 11 00 hours Local Mean Time and an ocean wind speed of 7 m/s. The influences due to Sun glitter for VTIR-2 to 4 are negligible. (5) A 38 per cent of influence caused by rim darkening is estimated for VTIR in the worst case. This would occur at the maximum viewing angle, in the summer, under a hazy atmospheric condition. (6) A 2·8 per cent influence on brightness temperature, caused by polarization change due to antenna rotation for the MSR, is estimated. (7) A 12·8 per cent influence on brightness temperature, caused by the side lobe effect for the MSR, is estimated for the case in which a land-ocean boundary coincides with the trough between the main and the first side lobe on the antenna pattern.
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