[U-03] 人新世・第四紀の気候および水循環

[U03-P06] Spatiotemporal Variability of Local Marine Reservoir Correction in the North Western Pacific

*Zeng Yuning¹、横山 祐典¹、平林 頌子¹、宮入 陽介¹、鈴木 淳³、阿瀬 貴博¹、川久保 友太² (1.東京大学大気海洋研究所、2.東京大学 理学部 地球惑星環境学科、3.国立研究開発法人産業技術総合研究所 地質調査総合センター)

キーワード：地域的な炭素リザボア効果、サンゴ放射性炭素

The surface ocean exchanges with the atmosphere and the ¹⁴C-depleted deep ocean, and has a ¹⁴C level intermediate between these two reservoirs. This results in an apparent ¹⁴C age of surface ocean samples several hundred years older than contemporaneous terrestrial samples. Such an apparent age is defined as the radiocarbon marine reservoir age (R). As the R value of a given location may be different than the model R of the “global” surface ocean (a difference between ¹⁴C age of a marine calibration curve (e.g., Marine20) and that of a terrestrial calibration curve (e.g., IntCal20) at a given time), the ¹⁴C age offset between these two values is expressed as the regional marine reservoir correction (ΔR). ΔR values are strongly influenced by local oceanographic conditions, such as ocean currents, deep-water upwelling, and inflow of freshwater, therefore they were used for reconstructing ocean circulation. Here we report more than two hundreds ΔR data from a coral in Kikai Island covering 1580-1950 CE and discuss how its spatiotemporal distribution varies with changes in oceanographic and climatic conditions.