The effects of Tsushima Warm Current on the interdecadal variability of the East/Japan Sea thermohaline circulation

Abstract

Using a four-box model with a throughflow system, it is shown that changes in the Tsushima Warm Current could induce thermohaline variability comparable to the ones observed in the northern deep part of the East/Japan Sea. When the current becomes stronger, salt flux to the northern surface area becomes larger. The vertical stability, then, weakens to produce warm and salty deep water through deep convection a few years after the maximum of the inflow. If the inflow salinity varies synchronously as well, deep convection could occur more easily. Interdecal variation in the atmospheric temperature also could induce thermohaline variability. When the air temperature is low, cold and fresh deep water would be formed. Therefore, neither the intensification of the current during 90s nor atmospheric cooling could explain the cold and salty deep convection observed during 2000-2001. Only when both effects are combined, the observed deep convection could be properly explained.