This ability to monitor a much larger range of wavelengths expands on the previous SeaWiFS capability. Significantly, it enables the sensor to measure chlorophyll fluorescence. Chlorophyll is a photoactive molecule that emits light in the red wavelength when excited by blue light, which provides an indicator of chlorophyll quality (competency) to go along with its quantity. This provides insight into the actual health of a phytoplankton bloom in addition to its magnitude.

In addition, the MODIS instrument's ability to detect very long wavelength radiation enables it to measure the temperature of surface waters, since the ocean's temperature is revealed by the infrared radiation it emits. Remember, upwelling is revealed by cooler waters rising to the surface, and thus by monitoring sea surface temperature and chlorophyll abundance we can detect both the physical process of upwelling and the biological response that results from it! MODIS instruments are mounted on two satellites (Terra and Aqua) as part of the Earth Observing System (EOS). The orbits of these satellites have been synchronously paired to allow for full coverage of the earth's surface every 1-2 days.