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Proceedings Paper

Patch recognition of algal blooms and macroalgae
Author(s): K. H. Szekielda; J. H. Bowles; D. B. Gillis; W. Snyder; W. D. Miller
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Paper Abstract

Fraunhofer lines and atmospheric absorption bands interfere with the spectral location of absorption bands of photosynthetic pigments in plankton. Hyperspectral data were used to address this interference on identifying absorption bands by applying derivative analysis of radiance spectra. Algal blooms show elevated radiance data even at longer wavelengths compared to oligotrophic water and may reach radiance values of around 800 W/m2/micrometer/sr at a wavelength of about 0.8 μm. Therefore, the use of a spectral range beyond 0.55 μm is useful to describe bloom characteristics. In particular, the slope between 0.55 μm to 0.80 μm shows an advantage to depict gradients in plankton blooms. Radiance spectra in the region from 0.4 to 0.8 μm for oligotrophic water and near coastal water show similar location of absorption bands when analyzed with derivative analysis but with different amplitudes. For this reason, radiance spectra were also analyzed without atmospheric correction, and various approaches to interpret radiance data over plankton blooms were investigated. Cluster analysis and ratio techniques at longer wavelengths were found to assist in the separation of ocean color gradients and distinguish bio-geochemical provinces in near-coastal waters. Furthermore, using the slope of spectra from plankton blooms, in connection with scatter diagrams at various wavelengths, shows that details can be revealed that would not be recognized in single channels at lower wavelength.

Paper Details

Date Published: 20 April 2010
PDF: 9 pages
Proc. SPIE 7678, Ocean Sensing and Monitoring II, 76780A (20 April 2010); doi: 10.1117/12.854772
Show Author Affiliations
K. H. Szekielda, The City Univ. of New York (United States)
J. H. Bowles, U.S. Naval Research Lab. (United States)
D. B. Gillis, U.S. Naval Research Lab. (United States)
W. Snyder, U.S. Naval Research Lab. (United States)
W. D. Miller, Computational Physics Inc. (United States)

Published in SPIE Proceedings Vol. 7678:
Ocean Sensing and Monitoring II
Weilin (Will) Hou; Robert A. Arnone, Editor(s)

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