The AMT4OceanSatFlux project is utilising an eddy covariance technique on board the 28th Atlantic Meridional Transect (AMT) cruise to measure the flux of carbon dioxide (CO2) between the atmosphere and ocean. These measurements will be used to validate a range of satellite products in order to gain regional and global estimates of gas exchange.
This programme builds upon the work of the AMT4SentinelFRM programme which made fiducial reference measurements at sea to calibrate and ensure the quality of data from the Sentinel satellites. This enables us to use the data from the satellites with greater confidence. With it we can address large scale issues and scientific questions on the effects of climate change in the global ocean, focusing on those that have a direct bearing on societal issues that humankind will face in the coming decades.
Why measure CO2 flux
Accurate measurements of CO2 flux are essential for a better understanding of how anthropogenic emissions of the greenhouse gas CO2 influence climate and the ocean’s role in the system. To date the oceans have absorbed around 40% of past emissions of CO2, this has a buffering effect on the atmospheric concentration of the gas, but is also changing the chemistry of the ocean.
The addition of eddy co-variance data to the range of high quality measurements on board the AMT cruise provides verification of state-of-the-art methods for estimating gas exchange. Combining multi-sensor data allows the calculation of global ocean-atmosphere CO2 fluxes, which is central to our understanding of how the oceans regulate increasing levels of CO2 and the extent to which this leads to ocean acidification. This large-scale analysis of satellite CO2 air-sea flux estimates has never been achieved before in the Atlantic Ocean.
left: eddy covariance set-up, centre: radiometers, right: optics rig being deployed
What is ocean acidification?
The absorption of CO2 is causing a gradual decrease in the pH of the oceans, a phenomenon called ocean acidification. This is having an adverse effect on many important marine species such as corals, oysters, crabs and plankton, and due to the unparalleled rate of acidification the organisms may not have time to evolve mechanisms to cope with the changing ocean chemistry.
What is the Atlantic Meridional Transect?
The Atlantic Meridional Transect (AMT) is a multidisciplinary programme which undertakes biological, chemical and physical oceanographic research during an annual voyage between the UK and destinations in the South Atlantic, a distance of up to 13,500km. The transect crosses a wide range of ecosystems from sub-polar to tropical and from euphotic shelf seas and upwelling systems to oligotrophic mid-ocean gyres making it an ideal platform for monitoring the health of our seas. The programme began in 1995 and provides a unique record of conditions in the Atlantic Ocean.