Operational MERIS-based NIR-red algorithms for estimating chlorophyll-a concentrations in coastal waters — The Azov Sea case study

Authors

• Wesley J. Moses, National Research Council/Naval Research LaboratoryFollow
• Anatoly A. Gitelson, University of Nebraska at LincolnFollow
• Sergey Berdnikov, Southern Scientific Center of the Russian Academy of SciencesFollow
• Vladislav Saprygin, Southern Scientific Center of the Russian Academy of SciencesFollow
• Vasily Povazhnyi, Southern Scientific Center of the Russian Academy of SciencesFollow

Document Type

Article

Date of this Version

2012

Citation

Remote Sensing of Environment 121 (2012) 118–124; doi:10.1016/j.rse.2012.01.024

Abstract

We present here results that strongly support the use of MERIS-based NIR-red algorithms as standard tools for estimating chlorophyll-a (chl-a) concentration in turbid productive waters. The study was carried out as one of the steps in testing the potential of the universal applicability of previously developed NIR-red algorithms, which were earlier calibrated using a limited set of MERIS imagery and in situ data from the Azov Sea and the Taganrog Bay, Russia, and data that were synthetically generated using a radiative transfer model. We used an extensive set of MERIS imagery and in situ data collected over a period of three years in the Azov Sea and the Taganrog Bay for this validation task. We found that the two-band and three-band NIR-red algorithms gave consistently highly accurate estimates of chl-a concentration, with a mean absolute error of 4.32 mg m⁻³ and 4.71 mg m⁻³, respectively, and a root mean square error as low as 5.92 mg m⁻³, for data with chl-a concentrations ranging from 1.09 mg m⁻³ to 107.82 mg m⁻³. This obviates the need for case-specific reparameterization of the algorithms, as long as the specific absorption coefficient of phytoplankton in the water does not change drastically, and presents a strong case for the use of NIR-red algorithms as standard algorithms that can be routinely applied for near-real-time quantitative monitoring of chl-a concentration in the Azov Sea and the Taganrog Bay, and potentially elsewhere, which will be a real boon to ecologists, natural resource managers and environmental decision-makers.