Alkenone temperature estimates for the East Sea during the last 190,000 years

The late Quaternary records of alkenone-based sea surface temperature (SST) from a core located in the western margin of the East Sea (Japan Sea) showed that the estimated temperature fluctuated greatly, the variability being consistent with orbital-scale global climate records. During the period of marine isotope stage (MIS) 6, the alkenone temperatures were low (7–10 °C), whereas during MIS 5.5 the temperature increased rapidly up to 21 °C. During the entire period of MIS 5, the temperature decreased from 21 °C to 13 °C. Then, the temperature fluctuated between 10 °C and 15 °C during MISs 4 and 3. After that, it continued to fluctuate between 15 °C and 17 °C. Variation in the East Sea SST is considered to be closely related to changes in the East Asian monsoon system and seawater transport by the Tsushima Warm Current. The glacial surface cooling could be associated with the strong winter monsoon and/or weakened summer monsoon in East Asia. During the glacial period, when the sea level was low, the influx of warm water was restricted and this might have enhanced the lowering of the surface temperature. These conditions most likely caused significant changes in surface water circulation. A basin-scale cyclonic gyre might have occurred in the East Sea without the development of the Subpolar Front. During the interglacial period, the surface warming seems to be related to the intensified summer monsoon system. The high stand of the sea level and climate change most likely caused the development of cyclonic and anti-cyclonic gyres in the north and south, respectively, and the Subpolar Front in the central part of the sea.