High-resolution Simulation of the Asian Summer Monsoon for the mid-Holocene and the Last Glacial Maximum

Abstract

Asian monsoon between the mid-Holocene and the LGM using results obtained by a relatively fine resolution numerical model. The simulations were performed with the Community Climate Model version 3 (CCM3) atmospheric general circulation model at about 75 km with 18 vertical levels. In the mid-Holocene summer, surface temperature increases in Asian continent by 3-5°C. Associated with the increase in surface temperature, surface pressure becomes deeper inside the continent and this intensifies the landward winds, especially the southwest wind in the Arabian Sea. An increase in landward winds is also shown in the northeast Pacific. In the LGM, on the other hand, the surface temperature decreases and consequently sea level pressure increases in the Tibetan Plateau, which leads to a marked decrease in southwest winds and thus the summer monsoon circulation. In conclusion, the Asian summer monsoon becomes stronger in the mid-Holocene and weaker in the LGM. These model results agree with observational proxy evidence and other previous model simulations.