Comparing solubility algorithms of greenhouse gases in Earth-System modelling

Abstract. Accurate solubility estimates are fundamental for (i) Earth-System models forecasting the climate change taking into consideration the atmosphere–ocean balances and trades of greenhouse gases, and (ii) using field data to calibrate and validate the algorithms simulating those trades. We found important differences between the formulation generally accepted and a recently proposed alternative relying on a different chemistry background. First, we tested with field data from the Baltic Sea, which also enabled finding differences between using water temperatures measured at 0.5 or 4 m depths. Then, we used data simulated by atmospheric (Meteodata application of WRF) and oceanographic (WW3-NEMO) models of the European Coastal Ocean and Mediterranean to compare the use of the two solubility algorithms in Earth-System modelling. The mismatches between both formulations lead to a difference of millions of tons of CO₂, and hundreds of tons of CH₄ and N₂O, dissolved in the first meter below the sea surface of the whole modelled region.