Interannual variations in net community production in the North Pacific Ocean

Accurate estimation of net community production (NCP) in the ocean and its interannual variations is important for determining the future trend for carbon dioxide concentrations in the atmosphere and thus for understanding the global carbon cycle and climate change. We used large data sets obtained from the North Pacific Ocean of seawater pCO₂ comprising approximately 940,000 data (obtained from 2003 to 2017; Surface Ocean CO₂ Atlas version 2019), which are 2 orders of magnitude greater than the dissolved inorganic carbon (DIC) data set; this enabled accurate resolution of the seasonal evolution of pCO₂ in the North Pacific Ocean. In particular, the combination of this data set with a surface alkalinity data set (Lee et al., 2006) and the established thermodynamic model for the seawater carbonate system should enable the seasonal evolution of DIC in the North Pacific from 2003 to 2017 to be accurately resolved. Our results based on direct observations showed considerable interannual variability in NCP in the North Pacific. Such large interannual variability appeared to be associated with large-scale climatic variability in the North Pacific basin.