Annual averaged alkalinity over the SMOS mission period 2010-2014 deduced from space borne SMOS SSS and GHRSST SST (OSTIA) products using the algorithm by Lee et al., 2006

As recently described in Land et al. (2015), approximately a quarter of the carbon dioxide (CO2) that we emit into the atmosphere is absorbed by the ocean. This oceanic uptake of CO2 leads to a change in marine carbonate chemistry resulting in a decrease of seawater pH and carbonate ion concentration, a process commonly called ‘Ocean Acidification’. Salinity data are key for assessing the marine carbonate system, and new space-based salinity measurements will enable the development of novel space-based ocean acidification assessment. Recent studies have highlighted the need to develop new in situ technology for monitoring ocean acidification, but the potential capabilities of space-based measurements remain largely untapped. Routine measurements from space can provide quasi-synoptic, reproducible data for investigating processes on global scales; they may also be the most efficient way to monitor the ocean surface. As the carbon cycle is dominantly controlled by the balance between the biological and solubility carbon pumps, innovative methods to exploit existing satellite sea surface temperature and ocean color, and new satellite sea surface salinity measurements, are needed and will enable frequent assessment of ocean acidification parameters over large spatial scales.

This work was conducted under the frame of the ESA STSE Pathfinders Ocean Acidification project  leaded by Dr Jamie Shutler (PML) and performed in collaboration with IFREMER. More details: http://www.pathfinders-oceanacidification.org