[A-CG47] Status and future view on global ocean observation: toward achievement and development for OneArgo

[ACG47-P03] Value chain of ocean CO₂ measurements for societal outcomes

*Masao Ishii¹, Naohiro Kosugi¹, Katsuya Toyama¹, Yosuke Iida², Shin-ichiro Nakaoka³, Yosuke Niwa³ (1.Meteorological Research Institute, 2.Japan Meteorological Agency, 3.National Institute for Environmental Studies)

Keywords:ocean carbon, air-sea CO2 flux, IPCC

Quantifying the variability of ocean CO₂ content and sea-air CO₂ flux in space and time and understating their controlling mechanisms and ocean carbon-climate feedbacks are important in projecting the consequences of increasing/reducing anthropogenic CO₂ emission on the CO₂ concentration in the atmosphere under Paris Agreement due to the insufficiency/success of activities toward zero-carbon emission. Today, data of surface pCO₂ measurements are collected mainly by ship-of-opportunity and onboard research vessels, quality-controlled and synthesized in the database SOCAT, and used to assess the variability of surface ocean pCO₂, sea-air CO₂ flux and the variables relevant to “the other CO₂ problem” ocean acidification such as pH and saturation index of calcium carbonate minerals from regional- to global-ocean scales. Similarly, data of ocean CO₂ system variables such as DIC and TA in the interior of the ocean have been collected together with other biogeochemical and physical ocean variables by research vessels under the international ocean observing network of the GO-SHIP and other national programs, quality-controlled and synthesized in GLODAPv2, and used to assess the variability of ocean carbon content due to changes in ocean circulation and biological activities and accumulation of anthropogenic carbon. These data of surface and interior ocean carbon have also been used to validate and/or improve global and regional ocean biogeochemistry models and for atmospheric CO₂ inverse models and ocean carbon inverse models as a prior. The results for carbon budget and scientific outcomes from these integrated scientific activities in addition to those from individual research programs such as those of time-series measurements are summarized in Global Carbon Project and in IPCC Working I Assessment Reports. They are used for international policy making in UNFCCC for actions toward zero carbon emission and to see their consequences on the carbon budget. However, these ocean carbon measurements are yet far from sufficiency, making the assessments of global ocean carbon budget uncertain. A development of extended and sustainable ocean observing network of BGC-Argo equipped with a high-quality pH sensor in particular in high-latitudinal zones in winter, in addition to the existing but vulnerable networks of research vessels and ship-of-opportunity, is expected to fill in the large gaps of ocean carbon measurements.