Oral B5 Coastal and Marine Ecosystems, Blue Carbon and Regional Ocean

2:00 PM - 2:15 PM JST(5:00 AM - 5:15 AM UTC)

[TPZePaqP-01] Development of a digital twin for estimating blue carbon sequestration by macroalgal beds from the coastal areas of Hokkaido to the open ocean

*Hiromichi Igarashi¹ (1. Japan Agency for Marine-Earth Science and Technology (Japan))

An accurate estimate of the potential distribution of blue carbon sequestration enables us not only to understand the processes of transport and its fate but also to evaluate the amount of stored carbon in the deep sea. We are now developing a digital twin framework for quantifying blue carbon sequestration by seagrass and macroalgal beds from the coastal waters around Japan by integrating field observation of seagrass and macroalgal production and export, oceanographic observation by research vessels, chemical analyses of sediment and water samples, decomposition experiments for tracing the fate of organic carbon derived from seagrasses and macroalgae, and ocean numerical model simulation. In this study, we developed a numerical simulation model for estimating blue carbon sink by macroalgal beds from the coastal area of Hokkaido Island to the open ocean. A 3-dimensional particle tracking technique was applied to transport of kelp (Saccharina longissima) from the coastal area to the open ocean, taking into account decomposition and size reduction processes, as well as the associated change of sinking velocity. As ocean environments, we used daily 3-dimensional (zonal, meridional and vertical) current velocity fields derived from an historical run of Future Ocean Regional Projection (FORP)-JPN02 (Ver.4) datasets produced by JAMSTEC and MRI-JMA. The horizontal resolution of FORP-JPN02 is 1/33*1/50 degree with 60 vertical levels, which can provide realistic fields of 3-dimensional ocean circulation and environmental structures around Japan coastal area to the open ocean. The result of our experiments suggests that a part of the kelp drifted from coastal area of Hokkaido is transported offshore and trapped within submarine canyon in several days and sinks rapidly to the deep sea. And not only DOC but also decomposed DIC rapidly transported into the deep-sea could contribute to long-term blue carbon sequestration.