Skip to main content

Remote Sensing: Ocean Color

The concentration of microscopic marine plants, called phytoplankton can be derived from satellite observations of ocean color. Phytoplankton account for half of the photosynthesis occurring on earth. Phytoplankton also play key roles in major chemical cycles. Because of their ability to draw down carbon from the atmosphere phytoplankton help the oceans sequester as much as half of the excess carbon dioxide we introduce into the atmosphere each year. Despite their importance concentrations of phytoplankton are extremely variable both in space and time. The impact they have on the environment varies by species as well. Fortunately it has become possible to monitor the productivity of the oceans using remotely sensed observations. This is feasible because chlorophyll and other plant pigments alter the absorption properties of the ocean in narrow spectral bands. The NASA Sea-viewing Wide Field-of-view Sensor (SeaWiFS), launched in 1997 measures upwelling radiances in eight bands spanning the visible and near-infrared, while MODIS, launched in 1999 measures 36 bands. The multiple bands allow scientists to correct for atmospheric effects as well as to distinguish among phytoplankton species by their reflectivity and relative pigment concentrations Professors Carton and Murtugudde are active in research to use ocean color satellite data for understanding the physical-biological interactions and bio-climate feedbacks, quantifying the role of biological pump in marine carbon cycle, application for climate monitoring and human health, diagnosing the coupled climate variability, and assimilation of satellite data for climate variability and prediction.

oc1
Eight-day mean chlorophyll-a concentration (mg/m3) derived from SeaWiFS, 21 to 28 August, 1998.
oc3
NOAA-14 AVHRR 3 channel color composite for August 25 1998, 20:16 UT
oc2
Water surface temperature from AVHRR for a time interval of about 7 days ending 1998 August 30 23:08 UT.