Temporal and Spatial Variations in Carbonate System and Air-Sea CO<sub>2</sub> Flux in the Kuroshio and Kuroshio Extension

Abstract

biological production due to the supply of nutrients from subsurface layers to the upper layer (Wooster and Reid 1963). The difference in the partial pressure of CO2 between the sea surface and the overlying air is one of the factors controlling the air-sea CO2 flux. Compared with the partial pressure of CO2 in the air (pCO2 air), the partial pressure of CO2 in surface seawater (pCO2 sea) varies largely, both in time and space. Therefore, it is the pCO2 sea that determines the direction of the CO2 flux between the sea surface and the air. By compiling numerous pCO2 sea data, Takahashi et al. (2009) have reported that the western North Pacific (WNP) is the area where the greatest air-sea CO2 flux (oceanic CO2 uptake) occurred in the Pacific Ocean, while the eastern North Pacific (ENP) is a weak sink for atmospheric CO2. In the Kuroshio extension, Ogawa et al. (2006) confirmed a large air-sea CO2 flux in 1999 and 2000 based on the voluntary observation ship pCO2 sea data. In the area including the Kuroshio extension (30– 40∞N, 150–180∞E), Takahashi et al. (2006) reported low decadal rates of change in Temporal and Spatial Variations in Carbonate System and Air-Sea CO2 Flux in the Kuroshio and Kuroshio Extension