Argo Program Achieves Milestone with Two Million Ocean Measurements

The international Argo network of ocean-observing robots just recorded its two millionth profile, marking a major milestone for the 20-year old observation program.

The robotic floats in the network were developed at Scripps Institution of Oceanography at the University of California San Diego in the 1990s. Now that nearly 4,000 of these floats are deployed in the world’s oceans, the network is giving scientists a comprehensive simultaneous view of all oceans that had never been available before. The maintenance and growth of the network has become a global effort on the part of U.S. agencies such as NOAA, the governments of more than two dozen other countries, academic centers, and support entities ranging from the U.S. Navy to private vessel operators.

“The Argo Program is a hallmark of NOAA’s ocean observing systems. It has revolutionized our ability to track changes in our global oceans,” said David Legler, research chief of the NOAA Ocean Observing and Monitoring Division. “In the wake of Hurricanes Michael and Florence, rising sea levels, and with an El Niño on the horizon, ocean information from systems like Argo is paramount for accurate weather and climate predictions.”

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Historically, science’s understanding of the ocean has come from satellite information, ship-based observations, moored buoys, and other anchored instruments. Torpedo-shaped Argo floats are able to sample much more of the global ocean, providing nearly four times the information as all other ocean observing tools combined. The free-floating devices that stand  five feet tall measure temperature and salinity in the ocean. Approximately every 10 days, an Argo float dives about 2,000 meters (1.2 miles) deep, drifts with the ocean currents, and then surfaces to transmit data in real-time via satellite. Argo floats cycle through these dives, or “profiles” for five years or longer on battery power.

Since its inception in 1999, the Argo Program has grown to include almost 4,000 floats and participation from 26 countries across the globe.

Even as it celebrates its two millionth profile, the Argo Program is expanding and innovating. New types of Argo floats are being tested. One of these floats is Deep Argo, which can dive three times deeper to the ocean bottom in depths up to 6,000 meters (3.7 miles), helping researchers understand the largely unobserved deep ocean. Another float type gaining international support is the biogeochemical Argo, a float that can measure a range of conditions such as oxygen, nitrogen , and pH: critical for addressing pressing environmental issues, such as ocean acidification and low oxygen levels that have been detected in some parts of the ocean. Argo leaders hope to integrate as many as 1,250 Deep Argo and 1,000 biogeochemical Argo floats into the global array to bring its total size to 4,600 floats in an effort beginning in 2020.

Major ocean and climate assessment programs, such as the Intergovernmental Panel on Climate Change (IPCC), already rely on Argo. It is a key tool used to track how fast the Earth’s climate is warming. All Argo data are freely available to anyone, and have been used for broad applications including aquaculture, pollution monitoring, ocean education, and national defense. On average, a scientific paper using Argo data is published every day.

U.S. Argo partners include the Scripps Institution of Oceanography, University of Washington, Woods Hole Oceanographic Institution, and NOAA’s Ocean Observing and Monitoring Division, Pacific Marine Environmental Lab, and Atlantic Oceanographic and Meteorological Lab. The U.S. Argo Program maintains about half of the global Argo fleet, deploying around 400 new Argo floats each year.

– Adapted from a NOAA news story