Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 128-136). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 124-130) / Microfiche. / x, 130 leaves, bound ill. 29 cm

Thesis (Ph. D.)--Texas A & M University, 1993. / Vita. Includes bibliographical references (p. 204-208).

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No description available.

Accurate retrieval of water-leaving reflectance from satellite-sensed signal is decisive for ocean color applications, because water-leaving radiance only account for less than 10% of satellite-sensed radiance. The standard atmospheric correction algorithm relies on black pixel assumption, which assumes negligible water-radiance reflectance at the near-infrared (NIR) bands. The standard NIR-based algorithm generally works well for waters where the NIR water-leaving radiance is negligible or can be properly accounted for. However, the black pixel assumption does not hold over turbid waters, which results in biased retrievals of remote sensing reflectance (Rrs). Therefore, this study aimed to improve atmospheric correction over turbid waters. Based on Sentinel-3, two ways to cope with nonzero NIR water-leaving reflectance were explored. First, this study proposed to use artificial neural networks to estimate and correct NIR water-leaving reflectance at TOA (ANN-NIR algorithm). The rationale of it is that hydrosol optical properties are much simpler at NIR spectral region, where pure water absorptions are the dominant factor. The proposed algorithm outperformed the standard NIR-based algorithm over highly turbid waters. Considering results demonstrated in this study, ANN-NIR algorithm should be useful for ocean color sensors with less than two SWIR bands. Second, this study adapted the SWIR-based algorithm for atmospheric correction of Sentinel-3 OLCI by coupling with the two SWIR bands of SLSTR. Three SWIR band combinations were tested: 1020 and 1613, 1020 and 2256, and 1613 and 2256 nm. The SWIR-based algorithm obviously performed better than NIR-based algorithm over highly turbid waters, while the NIR-based is still preferred for clear to moderately turbid waters. The SWIR band of 1020 nm combined with either SWIR band of 1613 or 2256 nm is recommended for the SWIR-based algorithm except for extremely turbid waters, because the band of 1020 nm has better radiometric performance. Over extremely turbid waters, the band combination of 1613 and 2256 nm should be used, since the water-leaving reflectance is still non-negligible at the band of 1020 nm over these waters. Considering atmospheric correction performance obtained by the NIR- and SWIR-based algorithms, the NIR-based and SWIR-based algorithm are practically applied over clear and turbid waters, respectively. This study revisited the effectiveness of the turbidity index for the current NIR-SWIR switching scheme. The turbidity index calculated from aerosol reflectance varies from 0.7 to 2.2, which is not close to one as expected. In addition to water-leaving reflectance, its value also depends on the spectral shape of aerosol reflectance, which varies with aerosol size distributions, aerosol optical thickness, relative humidity and observing geometries. To address this problem, this study proposed a framework to determine switching threshold for the NIR-SWIR algorithm. An Rrs threshold was determined for each MODIS land band centered at 469, 555, 645 and 859 nm, respectively. Their thresholds are 0.009, 0.016, 0.009 and 0.0006 sr-1, respectively. However, Rrs(469) tends to select SWIR-based algorithm wrongly for clear waters, while NIR-SWIR switching based on Rrs(859) tends to produce patchy patterns. By contrast, NIR-SWIR switching based on Rrs(555) with a threshold of 0.016 sr-1 and Rrs(645) with a threshold of 0.009 sr-1 produced reasonable results. Considering the contrasted estuarine and coastal waters, combined applications of NIR- and SWIR-based algorithm with the switching scheme should be useful for these waters. This study will contribute to better ocean color atmospheric corrections over turbid waters. Atmospheric correction algorithms based on black pixel assumption have been implemented and tested in this study, while combined applications of NIR-based and SWIR-based algorithms are recommended over contrasted transitional waters. However, further studies would still be required to further improve and validate atmospheric correction algorithms over turbid waters.

Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / M.S.

The atmospheric radiative transfer model MOCARAT was developed and is presented in this thesis. MOCARAT employs a Monte Carlo Technique for the accurate modeling of band radiances and reflectances in an atmospheric system with a ruffled ocean surface as a lower boundary. The atmospheric radiative transfer is modeled with consideration of molecular Rayleigh scattering, Mie Scattering and absorption on particulate matter, as well as band absorption by molecules in the wavelength channels of interest. The bidirectional reflection of downwelling light at the ocean surface is computed using the empirical relationship between surface wind field and the slope distribution of wave facets derived by Cox and Munk (1954a). A method is proposed to use the oceanic sun glint for remote sensing applications. The sensitivity of channel correlations to aerosol burden and type as well as other atmospheric and observational parameters is assessed. Comparisons of observed correlations with model results are used to check the consistency of the calibration of the airborne Multichannel Cloud Radiometer (MCR) that was employed during the Indian Ocean Experiment (INDOEX). The MCR calibration exhibited large variability from flight to flight. The method was applied to MODIS observations. Unlike the MCR, MODIS was stable where expected, although numerical values for some of the wavelengths appear to depart from theory. / Graduation date: 2004

The radiance distribution provides complete information regarding the geometrical structure of the ambient light field within the ocean. A quantitative study of the radiance field in the dynamic ocean water is presented in this thesis work. The study starts with the development of a novel radiance camera for the measurement of the full spherical radiance distribution at the ocean surface and depth. Nonlinear response functions are designed and advanced radiometric calibrations are developed. The resulting camera measures the radiance distribution in absolute units over an extremely high dynamic range at fast rates. With the newly obtained radiance data, I have examined the fine structure of both the downwelling and upwelling radiance distribution and its variation with depth in optically diverse water types. The fully specified radiance distribution data are used to derive all apparent optical properties and some inherent optical properties including the absorption coefficient. With the camera fixed at shallow depths, I have observed and determined the sea surface wave disturbance of the radiance distribution. It is found that the radiance fluctuates anisotropically with regard to its amplitude and periodicity. Typical spatial structures of the dynamic radiance field are identified and shown relevant to the surface waves and the solar zenith angles. The variability in the radiance field also propagates to the irradiance field; the variability is pronounced in measured irradiance depth profiles in the upper layers of the ocean. The statistics of the irradiance fluctuations along the water depth, including the dominant frequency and coefficient of variation, are derived using wavelet techniques and fitted to novel analytic models. The results from the irradiance depth-profile decomposition are in agreement with theoretical models and other independent measurements. This thesis work represents the first attempt to quantify the full light field and its variability in dynamic ocean waters and is of significant relevance to many other optics-related applications.

Thesis (M.S.)--Naval Postgraduate School, 1984. / "March 1984." "N0001484 WR24001"--P. 1. Includes bibliographical references (leaves 144-148).