Development of the East Korea Warm Current in the Hupo Trough of the southwestern East Sea (Japan Sea) since the Last Glacial Maximum based on TEX86 and [formula omitted] paleothermometers

Abstract

In this study, we documented seawater temperatures estimated from U37K′ and TEX86 using a sediment core (ES14-GC02) from the Hupo Trough influenced by the East Korea Warm Current (EKWC) and tested the applicability of the TEX86 paleothermometer to reconstruct seawater temperature variability of the EKWC since the Last Glacial Maximum (LGM). Compared to in situ observational data, U37K′ temperature on core-top sediment coincides with the average sea surface temperature (SST) during spring to fall, whereas TEX86 or TEX86L temperature corresponds to either the mean annual temperature at the subsurface (30–50 m) or the seawater temperature at the surface mixed layer during winter. TEX86 temperature has increased rapidly since the LGM, whereas its U37K′ temperature during the last glacial period was higher than the Holocene and has decreased rapidly since the last deglaciation. Both TEX86 and U37K′ temperatures indicate that the EKWC has been relatively stable since the mid-Holocene (i.e., ∼8.2 ka), despite a gradual increase and slightly larger fluctuation during the late Holocene. Our records also show that variation pattern between TEX86 and U37K′ was opposite and the centennial- to millennial-scale variability was within a range of ca. 4 °C during the late Holocene. The temperature change of the EKWC in the Hupo Trough seems to have strong linkage to the global/regional climate variability including the East Asian monsoon and El Niño Southern Oscillation. Finally, we suggest that TEX86 supplemented with SST by U37K′ can be applied to reconstruct the subsurface seawater temperature in the East Sea (Japan Sea).