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.