The Relative Merits of Narrowband Channels for Estimating Broadband Albedos

Abstract
Observations made with the current and proposed narrowband shortwave channels aboard the NOAA series of satellites were simulated for a number of different surfaces (ocean, vegetative land, desert, cloud and snow) using the ATRAD radiation model to study the relative merit of each channel and, in various combinations to predict the broadband albedo. Solar zenith angles were varied over the range from 0 to 60 degrees. The results indicated that for all of the surfaces considered there would be no significant difference in predicting the broadband albedo with either the current (0.58–0.68 μn) or proposed (0.58–0.68 μm) channel 1 of the AVHRR. The proposed narrower channel 2(0.84–0.87 μm), however, would be a better predictor than the current wider channel 2(0.725–1.0 μm). Channel 1 is better than channel 2 for surfaces of low or moderate reflectivity, while over snow, the error in using channel 2 would be less than half of that for channel 1. Combining channels 1 and 2 would reduce the error by abo... Abstract Observations made with the current and proposed narrowband shortwave channels aboard the NOAA series of satellites were simulated for a number of different surfaces (ocean, vegetative land, desert, cloud and snow) using the ATRAD radiation model to study the relative merit of each channel and, in various combinations to predict the broadband albedo. Solar zenith angles were varied over the range from 0 to 60 degrees. The results indicated that for all of the surfaces considered there would be no significant difference in predicting the broadband albedo with either the current (0.58–0.68 μn) or proposed (0.58–0.68 μm) channel 1 of the AVHRR. The proposed narrower channel 2(0.84–0.87 μm), however, would be a better predictor than the current wider channel 2(0.725–1.0 μm). Channel 1 is better than channel 2 for surfaces of low or moderate reflectivity, while over snow, the error in using channel 2 would be less than half of that for channel 1. Combining channels 1 and 2 would reduce the error by abo...

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