Introduction
High concentrations or "blooms" of the coccolithophorid Emiliania huxleyi can significantly affect a region by acting as a source of organic sulfur (i.e. dimethyl sulfide) to the atmosphere and calcium carbonate to the sediments, and by altering the optical properties of the surface layer. Documenting the occurrence of blooms in time and space is therefore essential in characterizing the biogeochemical environment of a region. Furthermore, their distribution pattern can be employed to define the environmental conditions favorable for their occurrence. E. huxleyi blooms can be distinguished from most other conditions in visible satellite imagery by their milkly white to turquoise appearance. We used this relatively unique spectral signature to detect the presence of these blooms in ocean color imagery of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS).
Methodology
Blooms of the coccolithophorid E. huxleyi were mapped in SeaWiFS ocean color data by classifying pixels of weekly (8-day) global composites into bloom and non-bloom classes using a supervised, multispectral classification scheme. This scheme was employed previously by Brown and Yoder (1994) to detect E. huxleyi blooms in Coastal Zone Color Scanner (CZCS) imagery. The algorithm has benn updated to incorporate differences between CZCS and SeaWiFS imagery. The classified images are accessible below.
Limitations
Conditions exist which mimic the spectral signature of E. huxleyi blooms. Consequently, these conditions will be incorrectly classified as E. huxleyi blooms.
Literature Cited
Brown, C. W., and Yoder, J. A. (1994a), Coccolithophorid blooms in the global ocean, J. Geophys. Res. 99:7467-7482.
Maps are available for the following years:
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