Pollen records of orbitally modulated variation in East Asian winter monsoon intensity and freshwater inflow to the Ulleung Basin of East Sea, South Korea, during the last glacial period

Abstract

Most pollen analysis in Korea has focused on the Holocene Epoch, because pre-last glacial maximum terrestrial archives suitable for palynological study in the Korean Peninsula are limited. Thus, to verify the responses of vegetation to climate changes over the orbital timescales, analysis of pollen in marine sediments is needed. Here, we present the pollen record of hemipelagic sediments of core DD09-ST21 obtained from the northern Ulleung Basin in the East Sea. The palynofloral assemblages were dominated by warm temperate broadleaved trees and boreal conifers during interglacial and glacial periods, respectively. We also demonstrated that bisaccate pollen and herbaceous pollen in the palynological sequence can be used as indicators of the variation in the East Asian winter monsoon (EAWM) intensity during the last glacial period and freshwater inflow into the East Sea, respectively. During glacial periods, the EAWM intensified in response to weakening of the summer insolation at 60 degrees N, while freshwater influx into the East Sea decreased due to a decrease in precipitation.