Orbital-scale Dynamics of the Eastern Asian Summer Monsoon

Abstract

Abstract Due to multiple factors influencing orbital-scale variability of the East Asian Summer monsoon (EASM), the interpretation of speleothem-based climate reconstructions from this region has remained challenging. Using a 130,000-year accelerated astronomically-forced simulation conducted with the isotope-enabled Community Earth System Model, we determine the drivers of orbital-scale EASM variability in oxygen isotopes (δ18O). Indian summer monsoon (ISM) and associated moisture transport changes control the strong precipitation-δ18O variability in the western part of the EASM domain on timescales of 21,000 years. In the eastern part of the EASM region, including Korea and Japan, the interactions between ISM, western North Pacific Subtropical High, and westerlies control precipitation-δ18O. Thus, precessional variability in precipitation-δ18O is suppressed by the compensating effects of oceanic and continental moisture sources.