Narrator: This is Science Today. An internationally coordinated global observing system called ARGO, which was set up to monitor Earth's oceans, is two-thirds complete. The free-floating, robotic devices have already collected nearly 55 thousand profiles from over 2,000 floats around the world.

Roemmich: We're trying to deploy at least 750 to 800 instruments every year, in order to both reach the three thousand float plateau and to hold it at that level.

Narrator: Dean Roemmich, a scientist at the University of California , San Diego's Scripps Institution of Oceanography, explains the program will eventually deploy 3,000 temperature and salinity profiling floats.

Roemmich: The profiling float is an autonomous instrument, self-contained, which can operate for about five years in the open ocean. And it makes a profile, every ten days, from about two thousand meters depth, measuring temperature and salinity as it goes up and then transmitting that data immediately back home.

Narrator: For Science Today, I'm Larissa Branin.