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Estimation of inherent optical properties and water constituent concentrations from the remote-sensing reflectance spectra in the Albemarle-Pamlico Estuary, USA

Leonid Sokoletsky(1) and Ross Lunetta(1)

(1) U.S. Environmental Protection Agency, 109 TW, Alexander Drive, 27711, Durham, United States

Abstract

The decomposition of remote sensing reflectance (RSR) spectra into absorption, scattering and backscattering coefficients, and scattering phase function is an important issue for estimating water quality (WQ) components. For Case 1 waters RSR decomposition can be relatively easily accomplished due to the small quantity of optically-active components and interrelationships of inherent optical properties (IOPs) induced by different water constituents. However, for inland and coastal waters, the situation is generally more complex because of the occurrence of high concentrations of WQ components and weak relationships between them and optical properties. Our research focused on an intermediate estuarine conditions within the Albemarle-Pamlico Estuary System (APES), North Carolina, USA. Field radiometric observations were performed using a Satlantic hyperspectral instrument and corresponding water constituent concentrations were measured using standard laboratory procedures. RSR decomposition was performed using the ENVISAT MERIS near-infrared to red ratios for the retrieval of IOPs and various WQ components including chlorophyll, volatile (organic), and total (organic+inorganic) suspended solids concentrations. Decomposition was accomplished using radiative transfer approximations, namely: extended quasi-single-scattering and extended Kubelka-Munk approximations for reflectance factor (bidirectional reflectance) and spherical albedo (bihemispherical reflectance), respectively. Derived estimates were validated for 40 near surface radiometric and WQ samples and demonstrated a high degree of correspondence. This method can be easily modified for both in situ and remote-sensing applications over broad range water conditions and locations.

 

Workshop presentation

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry