Western boundary currents flow along the western edge of ocean basins, transporting vast amounts of heat and moisture from equatorial regions to higher latitudes. The Kuroshio Current (KC) and the Kuroshio Current Extension (KCE) is the western boundary current system of the North Pacific Subtropical Gyre (Figure 1). The KC originates from the westward-flowing North Equatorial Current and has an estimated volume transport of 23.7-25.0 Sverdrup (Sv; 1 Sv = 1 million cubic meters per second) (Ichikawa & Beardsley, 1993). The current flows past the Izu Ridge until it separates from the Japan coast at approximately 36°N, 141°E flowing east into the Pacific Ocean (Imawaki et al., 2013) where it becomes the KCE. Maximum transport volume of the KCE has been estimated to reach up to 130 Sv (Wijffels et al., 1998). Thus, the KCE jet alone provides massive amounts of heat and moisture for North Pacific midlatitude cyclones. By modifying the path and intensity of storm tracks, changes to the dynamic state of the KCE can alter the stability and pressure gradient within the local atmospheric layers and basin-scale wind stress patterns (Frankignoul & Sennechael, 2007;Kwon et al., 2010) which, in turn, influences atmospheric processes affecting precipitation patterns over Japan and the west coast of North America (Latif & Barnett, 1994).The KCE region is one of the most dynamic and important regions of the world's ocean. Meeting of subtropical water masses brought north by the KC with southward flowing subpolar waters by the Oyashio Current (Figure 1) creates a relatively steep temperature gradient across these currents in the northwest Pacific. This condition leads to annual average water temperatures differing by about 8°C from 35°N to 40°N across the KCE and Oyashio Current (Locarnini et al., 2013). Measurements of air-sea CO 2 fluxes over