Spectral reflectance of whitecaps: Their contribution to water-leaving radiance
نویسندگان
چکیده
A radiometric system, deployed from a ship, is used to measure directly the influence of the presence of breaking waves (whitecaps) on the upwelling radiance above the sea surface. Estimates of their remote sensing augmented spectral reflectance, i.e., the temporally averaged or spatially averaged increase in the ocean’s reflectance over and above the reflectance in the absence of breaking waves, are provided from measurements in the tropical Pacific. The accuracy of these estimates is dependent on their ability to determine radiometrically the background reflectance of the water. In the visible the remote sensing augmented spectral reflectance of whitecaps measured in the open ocean was found to be essentially independent of wavelength and in the range 0.001–0.002 for wind speeds of 9–12 m s. This is in reasonably good agreement (within a factor of 2) with earlier predictions based on the statistical relationship between fractional coverage and wind speed and the estimated average reflectance of individual whitecaps. In the near infrared (860 nm) the remote sensing augmented spectral reflectance falls to ;80% of its value in the visible.
منابع مشابه
Estimating the Augmented Reflectance Ratio of the Ocean Surface When Whitecaps Appear
The presence of foam influences the accuracy of satellite-derived water-leaving radiance. A model has been developed to estimate the augmented reflectance ratio (A(λ, U)) due to differences in the fraction of whitecap coverage (w) on the ocean surface. A(λ, U) can be calculated from the product of w and ρ(λ, U), where ρ(λ, U) is the augmented ratio of the reflectance of background water (Rb(λ))...
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