Ten years of Spanish ion carbonate data in the North Atlantic Ocean and Mediterranean Sea

Concentration of ion carbonate has become the fifth measurable variable of the seawater CO2 system since the publication of the work by Byrne and Yao (2008) introducing a spectrophotometric method similar to the standard pH procedure. However, opposite to pH, the ion carbonate method has been refined and updated in a series of works(Easley et al., 2013; Patsavas et al., 2015; Sharp et al., 2017 and Sharp and Byrne, 2019) that introduced modifications in the equations relating the UV absorbance measurements and the final ion carbonate concentration, the reagent used and other details. Except for the USA seminal research group, and the two Spanish teams at the IEO A Coru??a and IIM-CSIC, no other oceanographic group has published research data using the ion carbonate spectrophotometric methods. The work by Fajar et al. (2015) used a collection of Spanish cruises from 2009 to 2014 to compare the initial spectrophotometric ion carbonate methods by Byrne and Yao (2008) and Easley et al. (2013).