Taking the Ocean's Temperature

Continued from page 1

By Mark Schrope

June 28, 2002

To acquire this data, the assimilation experiment partnered with Argo, an international effort to create a global network of deep-diving oceanographic sensors. Ships or planes drop Argo's sensor floats--each about the size and shape of a scuba tank-into the high seas. Typically, a floats sink to about 2,000 meters, measures salinity and water temperature for two weeks, then surfaces and transmits its location and collected data to a satellite (distances traveled between visits to the surface reveal the movement of deep-ocean currents). The float then sinks again, repeating this cycle for up to five years.

Dean Roemmich, a physical oceanographer at the Scripps Institution of Oceanography in La Jolla, CA, says Argo's aims to have about 3,400 floats in the water within three years. More than 400 are already operating; funding has been allocated by various countries for 1,500 more over the next two years, and money has been promised for the remaining 1,500. The U.S. will pay for about half of the total with other countries such as Japan, France and Canada funding the rest. The assimilation experiment will gather massive amounts of data from Argo floats, satellites and traditional sources. Sharfstein says preparations to process and disseminate it all are well under way at data centers around the globe.

Partners anticipate feeding this new data into computer models that will allow everything from long-term ocean forecasts to a clearer picture of daily conditions-or "nowcasts." This may lead to a long-term comprehensive record of ocean conditions that improves our understanding of global warming. Other potential benefits include allowing companies to plot the safest routes for their ships and enabling the military to better plan of naval operations.