Skip to main content
U.S. flag

An official website of the United States government

Fifth National Climate Assessment - Read the Report

Tracking ocean change

An Argo float equipped with newly developed oxygen sensors, pictured prior to deployment in the tropical Pacific Ocean, November 2020. Credit: NOAA.

New ocean sensors will expand the ability of the global Argo Program to monitor and forecast changes in ocean chemistry and marine ecosystem health.

The international Argo Program maintains a global fleet of nearly 4,000 ocean floats that help scientists understand how the ocean is changing over time. Underwater sensors provide data on trends related to climate change, including ocean temperature and heat content, salinity and freshwater content, sea level, and large-scale ocean circulation. Now, the program is innovating to improve measurements of ocean chemistry and other indicators important for management of marine ecosystems threatened by climate and global change.                                

Two new research projects, funded by NOAA and NASA, will partner with the private sector to improve floats equipped with sensors that can measure ocean acidity, oxygen and nitrate concentration, and phytoplankton productivity, important indicators of marine ecosystem health. The redesigned floats, known as BGC-Argo floats, will be deployed in the tropical Pacific Ocean to monitor variability in ocean biogeochemistry as a contribution to the Tropical Pacific Observing System, which supports forecasts of global shifts in climate and extreme weather associated with the El Niño– Southern Oscillation.

While NSF, NOAA, and NASA partners currently deploy floats with biogeochemical sensors as part of the Southern Ocean Carbon and Climate Observations and Modeling Project (SOCCOM) and the new NSF-funded Global Ocean Biogeochemistry Array (GO-BGC), more research is required to produce reliable floats that contain all needed sensors. These projects will improve sensor quality and float design and increase production of floats by introducing new vendors to the marketplace, with the eventual goal of establishing a sustained biogeochemical float array to monitor marine ecosystem health.