Spatial and temporal changes in sea surface temperature, circulation and subpolar front of the East Sea (Japan Sea) during the last 130,000 years

In order to reconstruct spatial and temporal changes in sea surface temperature (SST) of the East Sea (Japan Sea) on glacial–interglacial time scale, alkenone temperature records from the both Korean and Japan margins have been investigated for the period over the last 130 kyr. Results show that the temperature gradient between the Korean and Japan margins was relatively small (~ 2 °C) during the warm interval of the interglacial period (MIS 5e). But it was large (~ 10 °C) during the transitional period from the interglacial to the glacial (MIS 5a and b). The temperature of the Korean margin was colder than that of the Japan margin during the transitional period. Based on the reconstructed alkenone temperature, temporal changes in surface circulation and subpolar front (SPF) have been investigated. During the interglacial period when sea level was higher than today (MIS 5e), the influx of the Tsushima Warm Current (TWC) was enhanced and the both Korean and Japan margins were influenced by the warm water. At that time, the SPF appears to be located in the northern part compared to today. During the transitional period when the sea level was lower than today (MIS 5a and b), the TWC volume transport was reduced contributing to the lower SST. Its effect on the surface temperature appears to be larger along the Korean margin than the Japan margin, indicating that the strength of the East Korea Warm Current appears to be strongly correlated with the TWC volume transport. The SPF would displace southward orienting from southwest to northeast at that time. During the glacial period when the sea level was very lower (~ 100 m deep), the influx of warm water was almost completely restricted and the cold water expanded into the southern area. The SPF would disappear at that time. Model simulation results also support the relationship between the TWC volume transport and surface circulation and the SST.

► We reconstructed past sea surface temperature in the East Sea using alkenones.
► East–west SST gradient had been significantly changed during the MIS 5a and b.
► Decreasing the Tsushima Warm Current caused cooling in the Korean margin.
► We reconstructed changes in surface circulation and subpolar front from SST change.
► Numerical experiments with an OGCM confirm the proxy-based results.