지난최대 빙하기와 홀로세중기의 아시아몬순 고해상도 시뮬레이션

Abstract

The change in the Asian monsoon during the mid-Holocene (6,000 years before present (ka)) and Last Glacial Maximum (20 ka) is simulated by a high-resolution climate model. The model has horizontal resolution with spectral truncations of T170, which corresponds to grid cell sizes of roughly 75 km. The simulation was forced with observed present sea surface temperatures (SST) for the present, called MOD, and mid-Holocene simulation, called HOL, and CLIMAP SST reconstructions for the LGM simulations. Orbital parameters are changed to match at 6 ka and 20 ka and CO2 concentration is reduced to 200 ppm for the LGM simulation. With the 6 ka conditions, the precipitation associated with the summer monsoon is enhanced over wider zonal band from northern Africa to southeast Asia, whereas in winter there is not much change in precipitation. The surface wind also increases over the Arabian Sea showing the enhanced southwest wind during the summer. In the LGM, the precipitation associated with summer monsoon largely reduces over India and south-east Asia, even though there is an increase in precipitation over northern Africa and Saudi Arabia. The reduction in summer precipitation over India and south-east Asia seems to be due to the reduction in the south-west wind as shown in Fig. 1d. In winter, a moderate reduction in precipitation is simulated in the LGM. The change in precipitation is consistent with the proxy data of lake level reported by Kofheld and Harrison (2000) and de Noblet et al. (1996) for both the mid-Holocene and LGM. Overall, the high-resolution simulation captures detailed features of the Asian monsoon and the monsoon is enhanced during the mid-Holocene, especially in summer, and reduced in the LGM. This result is in a broad agreement with previous simulations (e.g., Bush, 2002).