The relation of chlorophyll-a concentration with the reflectance peak near 700 nm in algae-dominated waters and sensitivity of fluorescence algorithms for detecting algal bloom

Abstract

In order to investigate the relation of chlorophyll-a concentration with the reflectance peak near 700 nm, reflectance spectra of harmful algal bloom (HAB) species and non-HAB algae were obtained based on in situ measurements in the oceans and cultural tank data. It is found that the fluorescence line heights (FLH) of reflectance spectra and the concentrations of seawater chlorophyll-a have good correlation; their coefficients of determination are larger than 0.86, excepting Ceratium furca and Heterosigma akashiwo. It is specially noted that for some algae, such as Dicrateria zhanjiangensis Hu., Pyramimonas sp. and Nitzschia closterium, the corresponding coefficients of determination exceed 0.95. In addition, the various satellite fluorescence algorithms were compared, and the sensitivity of fluorescence algorithms was investigated. It is found that the designed bands of Medium Resolution Imaging Spectrometer (MERIS) are more reasonable than those of Moderate Resolution Imaging Spectroradiometer (MODIS) for detecting algal bloom.

Acknowledgements

This study was supported by the Project of Chinese Offshore Investigation and Assessment under Grant 908-02-03-01, the National Natural Science Funds of China under Grant 40876091, the Marine great projects for public welfare (200805064), the National High Technology Development Project of China under Grant 863-2005AA635200, 863-2006AA09Z140 and The National Basic Research Program of China under Grant 973-2007CB411807.