On the use of satellite-measured chlorophyll fluorescence for monitoring coastal waters

Images of solar-stimulated chlorophyll fluorescence are available from satellite sensors such as Medium Resolution Imaging Spectrometer MERIS and Moderate Resolution Imaging Spectroradiometer MODIS, and could be much more widely used for monitoring coastal productivity and plankton blooms. This article compares MODIS satellite images of sea-surface chlorophyll fluorescence, and of chlorophyll concentration as indicated by the standard green/blue ratio, using images made available at 1 km spatial resolution in near-real-time by the NASA Oceancolor web system. In some cases, the implied surface chlorophyll distributions from the two sources agree, and in others they show major differences. Significant disagreement occurs in some coastal waters, where the standard chlorophyll ratio product appears compromised by Coloured Dissolved Organic Material CDOM. The article shows images from western Canada, and from Bali and the Yellow Sea, areas of interest to present and past Pan-Ocean Remote SEnsing Conference PORSEC meetings. The Yellow Sea and to a lesser extent the Bali examples suggest value in fluorescence imaging. In western Canada, the case for using the fluorescence signal is much stronger, in that coastal blooms are much easier to detect using fluorescence rather than the standard ‘chlorophyll’ product.