Argo-based anthropogenic carbon concentration and inventory in the Labrador and Irminger Seas over 2011-2021

The ocean is a net sink for a quater of the carbon dioxide emitted to the atmosphere by human industrial activities and land-use change (C_ant). The North Atlantic Ocean encompasses the highest ocean storage capacity of C_ant per unit area. In particular, the Labrador and Irminger Seas are two basins storing a high amount of C_ant due to the deep convection activity taking place there. The temporal evolution of C_ant concentration in these two basins and their C_ant inventories in the 0-1800 depth layer are estimated over the period 2011-2021. The C_ant values are estimated from Argo floats equipped with oxygen sensors, predictive neural networks (ESPER_NN and CONTENT) and a carbon-based back-calculation method (φC^O_T method). On average, C_ant inventories are similar in the two basins and amount to 75.3 and 75.6 mol/m² in the Irminger and Labrador seas, respectively. Over the study period, Cant inventories increase in the two basins at a storage rate of 1.01±0.14 mol/m²/yr in the Irminger Sea and 0.94±0.2 mol/m²/yr in the Labrador Sea. The processes involved in Cant evolution in the two basins are then investigated.