Year
2019
Operation Area
Southern Ocean
Problem
The Southern Ocean plays a critical role in the global carbon cycle, absorbing large amounts of carbon dioxide from the atmosphere and helping regulate Earth’s climate. But it is also one of the most remote and hostile marine environments on the planet, with extreme winds, freezing temperatures, towering waves, and limited opportunities for sustained ship-based observations.
As a result, scientists have historically relied on sparse data collected by research vessels and autonomous floats, leaving major gaps in understanding how much CO2 the Southern Ocean absorbs—or releases—across seasons, especially during the stormy winter months. These blind spots limit the accuracy of climate models and make it difficult to predict how the ocean’s role in carbon uptake may change over time.
Solution
Saildrone deployed an unmanned surface vehicle (USV) equipped with a NOAA-developed ASVCO2 instrument to directly measure air-sea carbon fluxes in the Southern Ocean. Designed for long-duration missions in extreme conditions, the Saildrone USV enabled persistent, high-resolution observations in areas and seasons that are difficult, dangerous, and costly to reach with crewed ships.
The 196-day mission launched from Bluff, New Zealand, on January 19, 2019, and returned to the same port on August 3 after sailing more than 11,879 nautical miles around Antarctica. Throughout the circumnavigation, the USV collected critical ocean and atmospheric data, including measurements of CO2 exchange between the ocean and atmosphere, helping scientists better understand the Southern Ocean’s role in the global climate system.
Outcome
The mission delivered a first-of-its-kind data set from one of the most important and least-observed regions of the global ocean. By collecting direct, high-frequency measurements of air-sea CO2 exchange during the first autonomous circumnavigation of Antarctica, Saildrone helped scientists reduce uncertainty in estimates of how much carbon the Southern Ocean absorbs from—and releases to—the atmosphere.
The data have contributed to peer-reviewed research on Southern Ocean carbon flux, including a 2021 study in Geophysical Research Letters that used Saildrone observations to produce hourly CO2 flux estimates and evaluate how sampling frequency, wind speed, and sparse observations affect estimates of Southern Ocean carbon uptake. The mission also provided valuable context for subsequent research on the role of Southern Hemisphere storms in driving CO2 outgassing, including a 2024 study in npj Climate and Atmospheric Science showing that extratropical storms can play an important role in air-sea carbon exchange across the Southern Ocean.
Together, these findings reinforce the importance of persistent surface observations in regions that are difficult to reach with crewed ships, especially during winter and extreme weather. The mission helped demonstrate that Saildrone USVs can collect scientifically valuable data in the world’s harshest ocean conditions, supporting more accurate climate models and a deeper understanding of the Southern Ocean’s role in the global carbon cycle.
Additionally, the public-private partnership between NOAA’s Pacific Marine Environmental Laboratory and Saildrone was recognized with the 2020 Ron Brown Excellence in Innovation Award for demonstrating the ability to manufacture, test, and pilot world-class USVs. Saildrone also partnered with the 1851 Trust to develop a series of free STEM lesson plans based on the mission. Click to access the lesson plans.
