Revisiting the connection between variations in the Tsushima Warm Current and winter rainfall along the coast of Japan

Abstract

Enhanced autumn transport via the Tsushima Warm Current (TWC) has been reported to increase winter rainfall along Japan’s northern coast. However, observations reveal a significantly weakened correlation after 2006. Although enhanced transport via the Eastern channel of the Tsushima Strait affects rainfall by enhancing latent heat flux along Japan’s northern coast, the role of oceanic flows in varying sea-surface temperatures has weakened since 2006. Stronger northwesterly winds co-occur with enhanced surface heat loss that overwhelms the impact of the TWC. Our findings imply that atmospheric conditions should be considered when using TWC transport as a precursor for winter rainfall.