Surface Ocean pH Estimation: a Satellite Perspective

Chair: Thomas Trull

Roberto Sabia (1), Diego Fernández-Prieto (2), Jamie Shutler (3), Craig Donlon (4), Peter Land (5), Nicolas Reul (6)

1 Telespazio-Vega UK Ltd for European Space Agency (ESA), ESRIN, Frascati, Italy.
2 European Space Agency (ESA), ESRIN, Frascati, Italy.
3 University of Exeter, Exeter, United Kingdom.
4 European Space Agency (ESA), ESTEC, Noordwijk, the Netherlands.
5 Plymouth Marine Laboratory, Plymouth, United Kingdom.
6 IFREMER, Toulon, France.

The overall process commonly referred to as Ocean Acidification (OA) is nowadays gathering increasing attention for its profound impact at scientific and socio-economic level, as one of the major foci of climate-related research. To date, the majority of the scientific studies into the potential impacts of OA have focused on in-situ measurements, laboratory-controlled experiments and models simulations. Satellite remote sensing technology have yet to be fully exploited and could play a significant role by providing synoptic and frequent measurements, upscaling and extending in-situ carbonate chemistry measurements on different spatial/temporal scales, for investigating globally OA processes.

Within this context, the purpose of the ESA “Pathfinders – Ocean Acidification” project is to quantitatively and routinely estimate surface ocean pH by means of satellite observations in five case-study regions (global ocean, Amazon plume, Barents sea, Greater Caribbean, Bay of Bengal).

Satellite Ocean Colour, Sea Surface Temperature (SST) and Sea Surface Salinity (SSS) are being exploited, with an emphasis on the latter. A proper merging of these different satellites datasets will allow to compute at least two independent proxies among the seawater carbon dioxide system parameters: namely, the partial pressure of CO2 in surface seawater (pCO2); the total Dissolved Inorganic Carbon (DIC) and the total alkalinity (AT). Through the knowledge of these parameters, the final objective is to come up with the currently best educated guess of the surface ocean pH.

The innovation of this study lies mainly in the effort of unifying fragmented remote sensing studies and generating a novel value-added satellite product: a global and frequent surface ocean pH “cartography”. This will foster the advancement of the embryonic phase of OA-related remote sensing and will aim at bridging the gap between the satellite and the process studies communities, benefiting from their cross-fertilization and feedback.