Important features in the global pattern of phytoplankton are the high concentration (red and yellow) at high latitudes in the Northern Hemisphere, the relatively low concentration in the Southern Hemisphere, and the very low concentration (purple and blue) in mid-latitudes.
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Global distribution of phytoplankton concentration is indicated by ocean color. Oceanographic data were collected by the Coastal Zone Color Scanner on NASAΓÇÖs Nimbus-7 satellite. An improved ocean color data set is now being obtained with SeaWiFS.
