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Proceedings Paper

Remote sensing of solar-stimulated phytoplankton chlorophyll fluorescence by differential absorption in the oxygen B-band
Author(s): Robert Frouin; Pierre-Yves Deschamps; Philippe Dubuisson
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Paper Abstract

A new methodology is proposed to estimate from space the solar-induced chlorophyll fluorescence of natural waters. The methodology exploits absorption in the oxygen B-band around 687 nm, located near the peak of fluorescence emission at 685 nm. Inside the oxygen absorption lines, the fluorescence signal enhances the reflected solar radiance. By using a pair of spectral bands inside and outside the absorption region, or more generally spectral bands for which oxygen absorption is sufficiently different, the emitted contribution to the measured radiance can be extracted. Feasibility is demonstrated and retrieval accuracy quantified through simulations of the top-of-atmosphere reflectance by a radiation transfer code that fully accounts for multiple scattering and interactions between scattering and absorption. The differential absorption method works well from just above the surface. Pairs of spectral bands centered on the same wavelength provide the best results. Using spectral bands of 686.8-688.3 nm and 683.1-692.0 nm, the expected accuracy on fluorescence retrievals is <10% for chlorophyll concentrations above 1 mgm-3. Performance is degraded from space, due to the influence of aerosol vertical structure on the oxygen transmittance associated with path reflectance. In this case, knowledge of aerosol reflectance and optical thickness is required, but assuming an average aerosol vertical distribution yields reasonable results. In comparison with the standard baseline technique, significant improvements in retrieval accuracy are expected in Case II waters, especially in the presence of sediments.

Paper Details

Date Published: 19 December 2008
PDF: 12 pages
Proc. SPIE 7150, Remote Sensing of Inland, Coastal, and Oceanic Waters, 715005 (19 December 2008); doi: 10.1117/12.806386
Show Author Affiliations
Robert Frouin, Scripps Institution of Oceanography, Univ. of California, San Diego (United States)
Pierre-Yves Deschamps, Univ. des Sciences et Technologies de Lille (France)
Philippe Dubuisson, Univ. des Sciences et Technologies de Lille (France)

Published in SPIE Proceedings Vol. 7150:
Remote Sensing of Inland, Coastal, and Oceanic Waters
Robert J. Frouin; Serge Andrefouet; Hiroshi Kawamura; Mervyn J. Lynch; Delu Pan; Trevor Platt, Editor(s)

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