Radiative transfer in the coupled atmosphere-sea ice-ocean system with application in remote sensing

The change in the index of refraction across the interface between the atmosphere and the underlying aquatic medium affects the transport of radiation throughout this coupled system. This study shows that the downward solar irradiance can be significantly enhanced across this interface. A quantitative theoretical examination of this effect shows that the enhanced downward irradiance depends primarily on the change in the index of refraction across the interface, and the optical properties of the underlying medium. The solar zenith angle and the sky condition (clear versus cloudy) are also important. This enhancement downward irradiance effect has a strong influence on the radiative energy disposition throughout the atmosphere-sea ice-ocean system.; A complete model for the inherent optical properties of fresh lake water is developed on the basis of laboratory measurements of absorption coefficients (a) obtained from water samples, and in situ measurements of attenuation coefficients of downwelling irradiance (K_d) for solar UV radiation at four discrete wavelengths (305, 320, 340, 380 nm) reported in the literature. The model for the absorption coefficient is readily extended to the shortest wavelength in the UV-B spectral range (280 nm). The scattering coefficient (b) in the UV spectral range is obtained from the derived absorption coefficient ( a) and the measured attenuation coefficient (K_d) by simulating the radiative transfer process throughout the air-water system. This bio-optical model can be used to quantify the underwater light field in the UV spectral range, and to investigate the effects of UV-B radiation on aquatic ecosystems.; A method is presented for estimating the backscattering coefficient of coastal oceanic water directly from in situ measurements of the spectral attenuation and absorption coefficients. The method relies on the use of an analytic scattering phase function compatible with an assumed particle size distribution. An attractive feature of this method is that it provides a reasonable estimate of the Volume Scattering Function or the scattering phase function. The accuracy of this method depends on the assumed mean index of refraction of the particles and is comparable to that of other methods used to determine the backscattering coefficient.; A preliminary theoretical study of a vector discrete ordinate radiative transfer model for the coupled atmosphere-water system is performed. This development provides a basis for investigating polarization properties of the light field in the coupled atmosphere-water system.