Indian Ocean, chlorophyll concentration and clouds. Computer graphic of the Indian Ocean on an Earth globe, generated using satellite and mapping data. Satellite-measured ocean chlorophyll concentrations are colour-coded: high values in red, yellow and green, low values in blue and purple. Chlorophyll is present in photosynthesising plankton blooming where nutrients are concentrated where currents meet, deep water upwells, or nutrients run off from the land. Chlorophyll and cloud data obtained by the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA's Aqua and Terra satellites respectively.