Wind-driven pollen records implication of the East Asian winter monsoon changes during the last glacial period

Abstract

Pollen analysis was conducted on piston core taken from northern part of the Ulleung Basin, Korea, in order to unravel vegetation and climate changes during the last glacial period. The marine pollen records represent the orbital-scale variation: warm to cool temperate trees and boreal conifer increased in interstadial and stadial periods, respectively. In particular, fluctuations in relative abundance of conifer bisaccate pollen are likely linked to the intensity change of the East Asian winter monsoon. This is based on the fact that the relative amounts of bisaccate pollen are mainly controlled by the intensity of wind because they have a higher aerodynamic and lower hydrodynamic efficiency than other pollen. A close correlation between the variation of wind-driven bisaccate pollen and other records representing the East Asian winter monsoon also supports this interpretation. Bisaccate pollen increase sharply during the periods of MIS 2 and 4,reflecting that the East Asian winter monsoon was intensified during the two periods.