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The AMT4OceanSatFlux project is utilising an eddy covariance technique on board the 28th Atlantic Meridional Transect (AMT) cruise to measure gas exchange. These measurements will be used to validate a range of satellite products in order to gain regional and global estimates of the flux of CO₂ between the atmosphere and the Atlantic Ocean.

These measurements are needed for a better understanding of how anthropogenic emissions of the greenhouse gas CO₂ influence climate and the ocean’s role in taking up or releasing CO₂ to the atmosphere. 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 absorption of CO₂ is causing a gradual increase 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.

The project will also measure surface roughness, sea-surface height, ocean colour and sea surface temperature (SST) at unprecedented spatial and temporal resolutions using Sentinel satellites, combined with data from other satellite missions (NASA, NOAA, JAXA). This will give us a means of achieving global monitoring of the rise in SST, CO₂ and variability in the air-sea gas flux of our blue planet.

Dr Gavin Tilstone, Principal Investigator for AMT4OceanSatFlux said:

“The addition of eddy co-variance data to the range of high quality measurements being taken on board the AMT campaign 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.”

This programme builds upon the work of the AMT4SentinelFRM programme which made fiducial reference measurements at sea to validate and ensure the highest quality of data from ocean satellite missions. 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.

AMT4OceanSatFlux is funded by the European Space Agency and is led by Plymouth Marine Laboratory, and involves scientists from the University of Southampton, The University of Exeter and the Institut Français de Recherche pour l’Exploration de la Mar, Plouzane, France (IFREMER).

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.