Dissertation/Thesis Abstract

The polarization of light in coastal and open oceans: Reflection and transmission by the air-sea interface and application for the retrieval of water optical properties
by Foster, Robert, Ph.D., The City College of New York, 2017, 233; 10254604
Abstract (Summary)

For decades, traditional remote sensing retrieval methods that rely solely on the spectral intensity of the water-leaving light have provided indicators of aquatic ecosystem health. With the increasing demand for new water quality indicators and improved accuracy of existing ones, the limits of traditional remote sensing approaches are becoming apparent. Use of the additional information intrinsic to the polarization state of light is therefore receiving more attention. One of the major challenges inherent in any above-surface determination of the water-leaving radiance, scalar or vector, is the removal of extraneous light which has not interacted with the water body and is therefore not useful for remote sensing of the water itself. Due in-part to the lack of a proven alternative, existing polarimeter installations have thus far assumed that such light was reflected by a flat sea surface, which can lead to large inaccuracies in the water-leaving polarization signal. This dissertation rigorously determines the full Mueller matrices for both surface-reflected skylight and upwardly transmitted light by a wind-driven ocean surface. A Monte Carlo code models the surface in 3D and performs polarized ray-tracing, while a vector radiative transfer (VRT) simulation generates polarized light distributions from which the initial Stokes vector for each ray is inferred. Matrices are computed for the observable range of surface wind speeds, viewing and solar geometries, and atmospheric aerosol loads. Radiometer field-of-view effects are also assessed. Validation of the results is achieved using comprehensive VRT simulations of the atmosphere-ocean system based on several oceanographic research cruises and specially designed polarimeters developed by the City College of New York: one submerged beneath the surface and one mounted on a research vessel. When available, additional comparisons are made at 9 km altitude with the NASA Research Scanning Polarimeter (RSP). Excellent agreement is achieved between all instrumentation, demonstrating the accuracy of the modeling approach and validating the computed Mueller matrices. Further, the results are used to demonstrate the feasibility for polarimetric retrieval of the total attenuation coefficient for Case II waters, a feat which is not possible using scalar remote sensing methods.

Indexing (document details)
Advisor: Gilerson, Alexander
Commitee: Chowdhary, Jacek, Gross, Barry, Moshary, Fred, Tzortziou, Maria, Weng, Fuzhong
School: The City College of New York
Department: Electrical Engineering
School Location: United States -- New York
Source: DAI-B 78/08(E), Dissertation Abstracts International
Subjects: Ocean engineering, Optics, Remote sensing
Keywords: Instrumentation, Oceanic research cruises, Optical oceanography, Polarization of light, Remote sensing, Vector radiative transfer
Publication Number: 10254604
ISBN: 978-1-369-61745-0
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