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.

Environmental Forcing of Red Tides in the Southern Benguela

“…Since 2002, the moderate resolution imaging spectroradiometer (MODIS) provides declouded 8-day 9 km resolution imagery in 405-877 nm spectral bands that enable a fluorescence line height (FLH) calculation [30]. MODIS FLH is found to be consistent with in situ observations of red tide [31][32][33] as a radiometric index of relative harmful phytoplankton biomass. The European MERIS satellite also has spectral bands across the fluorescence peak capable of detecting red tides and cyanobacteria blooms [34], even in coastal turbid waters [35].…”

A new approach to discriminate dinoflagellate from diatom blooms from space in the East China Sea

“…Hu et al [2005] demonstrated that MODIS FLH provided more reliable information than the ratio-derived Chl product on the relative distribution of the bloom patches in the complex Florida coastal environment, despite some artifacts in the data and uncertainty attributed to factors such as unknown fluorescence efficiency. This approach was also found valid in China's coastal waters, usually with a doubled value of FLH over the background level as a bloom indicator [e.g., Li et al, 2011;Shang et al, 2012;Zhao et al, 2010].…”

Three decades of ocean-color remote-sensing Trichodesmium spp. in the World’s oceans: A review

“…Gower et al (2008) stated that the radiance maximum at 709 nm is indicative of phytoplankton biomass in excess of 30 mg Chla m À3 . In addition, research has shown that the magnitude of the MERIS 709 nm band can be related to Chla-specific concentrations of phytoplankton (Zhao et al, 2010). Unfortunately, no quantitative relationships have yet been established between the MCI and Trichodesmium abundance and warrants further investigation.…”