The Southern Ocean is a keystone for the most important ocean currents. there is an intensive exchange of gases between the atmosphere and the ocean. The flux of CO2 in the Southern Ocean is the balance between the emission to the atmosphere from the waters lifted from the depths by upwelling and the absorption of this gas and heat from the atmosphere in the surface layer. The balance between these processes is related to the value of the pressure difference between 40o and 65o S, described as the Antarctic Oscillation (AAO) value. The positive AAO index promotes the upwelling and reduction of CO2 absorption, a negative AAO value enhances the absorption of this gas by ocean waters.
A significant limitation for the models describing this equilibrium were local differences in the response of the CO2 stream to AAO conditions. This generated the need to gauge this phenomenon with an accuracy exceeding the capabilities of research vessels operating in the area of 30% of the Global Ocean. The answer to this need was the Uncrewed Surface Vehicle (USV), designed by engineers from the Li Ka Shing Foundation, NOAA and PMEL. During 192 days of the mission, the device traveled 22,000 km, conducting continuous measurements of wind force and velocity as well as CO2 concentration above the water and in the surface layer. The survey results were published in Geophysical Research Letters.
Measurement data is available in the National Centers for Environmental Information NOAA database.
The illustration is taken from A. J. Sutton et al. 2021