ESA contributes to ocean carbon cycle research

A GlobColor chlorophyll product showing the distribution of phytoplankton in the Atlantic Ocean and Mediterranean Sea. Click here for more information.

The Earth’s oceans play a vital role in the carbon cycle, making it imperative that we understand marine biological activity enough to predict how our planet will react to the extra 25 000 million tonnes of carbon dioxide humans are pumping into the atmosphere annually.

The colour of oceanic seawater depends largely on the number of microscopic phytoplankton, marine plants that live in the well-lit surface layer. Just like land-based plants, phytoplankton accumulate carbon dioxide during photosynthesis and store it in their tissues, making them potentially important carbon sinks.

While phytoplankton themselves are individually microscopic, the chlorophyll they collectively contain colours the ocean's waters, which provides a means of detecting these tiny organisms from space with dedicated ocean colour sensors.

To support ocean carbon cycle research, ESA’s GlobColour project has merged 55 terabytes of data from three state-of-the-art instruments aboard different satellites, including MERIS aboard ESA’s Envisat, MODIS aboard NASA’s Aqua and SeaWiFS aboard GeoEye’s Orbview-2, to produce a 10-year dataset of global ocean colour stretching to 2007.

"I am quite impressed by the work ESA has done so far within GlobColour," said Dr Cyril Moulin of the International Ocean Carbon Coordination Project (IOCCP). "This 10-year dataset is going to be very useful for carbon studies and global modelling."