Long-term variations in ocean acidification indices in the Northwest Pacific from 1993 to 2018

Abstract Long-term variations in ocean acidification indices the Northwest Pacific were examined using observational data and a biogeochemical model with an operational product for period 1993–2018. The surface (< 100-m depth) exhibit consistent patterns of subtropical Kuroshio Extension regions relative alkalinization (i.e., reduced acidification) subarctic region Pacific. Below depth, dominated regions. We attribute excess to vertical mixing dissolved inorganic carbon (DIC) exceeding DIC release by air–sea exchange. These regional differences are attributed spatially variable biological processes upper horizontal physical redistribution DIC. Our results have implications spatial extent pattern acidification, along strength sink, which key aspects global climate change.