Global monitoring of plankton blooms using MERIS MCI

Abstract

The MERIS maximum chlorophyll index (MCI), measuring the radiance peak at 709 nm in water-leaving radiance, indicates the presence of a high surface concentration of chlorophyll a against a scattering background. The index is high in 'red tide' conditions (intense, visible, surface, plankton blooms) and is raised when aquatic vegetation is present. A bloom search based on the MCI has resulted in the detection of a variety of events in Canadian, Antarctic and other waters round the world, as well as detection of extensive areas of pelagic vegetation (Sargassum spp.), previously unreported in the scientific literature. Since 1 June 2006, global MCI composite images, at a spatial resolution of 5 km, are being produced daily from all MERIS (daylight) passes of reduced resolution (RR) data. The global composites significantly increase the area now being searched for events, although the reduced spatial resolution may cause smaller events to be missed. This paper describes the composites and gives examples of plankton bloom events that they have detected. It also shows how the composites are affected by the South Atlantic anomaly (SAA), where cosmic rays impact the detectors of the MERIS instrument.

Space station image captures a red tide ciliate bloom at high spectral and spatial resolution

“…However, Chl a, which is found in all phytoplankton, fluoresces in far red wavelengths of ∼678 nm. Although not contributing significantly to the color observed by the human eye (15), the amount of natural fluorescence and backscattering at far red wavelengths can be used to detect surface blooms of phytoplankton without contamination by CDOM and minerals (19,20). Measurements at a resolution of 1 km from the Moderate Resolution Imaging Spectrometer (MODIS) Terra sensor on September 23, 2012 revealed the heterogeneous distribution of Chl a in the sound and, in particular, a patchy ∼20-km 2 bloom covering our field station in WLIS (Fig.…”

Monitoring of the 2011 Super Algal Bloom in Indian River Lagoon, FL, USA, Using MERIS

“…Moses et al [25] suggested that atmospheric correction may negatively influence the Chl a signal in highly turbid, shallow waters. The IRL system is shallower (depths of 1.5-3 m) than the coastal systems used in previous studies by Moses et al [25] and Mishra and Mishra [22]. The Azov Sea and Delaware Bay used by Moses [24,27] had average depths of 9 m and 2.5-10 m, respectably [32] and 6-30 m in the Chesapeake Bay used by Mishra and Mishra [33].…”

“…Atmospheric correction resulted in less accurate reports as most atmospheric correction methods were not designed with the Chl a fluorescence peak in mind and subsequently overcorrected the red and NIR spectrums in areas of high Chl a concentrations [8]. Additionally, this algorithm is cautioned to be used as qualitative and was discouraged from use for estimating concentrations of Chl a [22]. As a result of the MCI, several Chl a algorithms have been developed that utilize the MERIS 708 nm bands in an effort to estimate Chl a concentrations utilizing FR reflectance data.…”

Evaluation of MERIS Chlorophyll-a Retrieval Processors in a Complex Turbid Lake Kasumigaura over a 10-Year Mission

“…MERIS band 8 shifted from the fluorescence peak at 685-nm to 681-nm to avoid the effects of oxygen absorption at 687-nm [21]. Similarly, the MCI algorithm was developed for MERIS data to detect harmful algal blooms (HABs), such as the red tide, by determining the height of radiance at 709-nm over a baseline between radiance values at 681-nm and 754-nm [23]:…”

“…Several algorithms based on band height have been developed for the MERIS sensor; namely, the fluorescence line height (FLH) [21], the maximum chlorophyll index (MCI) [22,23], and the maximum peak height (MPH) [24]. The regression approach (e.g., linear) is required to establish a relationship between the Chla indices (i.e., FLH and MCI) and measured Chla.…”