Modeling the East Asian climate during the last glacial maximum

Using the CCM3 global climate model of National Center for Atmospheric Research (NCAR), this paper comparatively analyzes the characteristics of East Asian monsoon and surface water condition and the expansion of glacier on the Qinghai-Xizang (Tibetan) Plateau (QXP) between the present and the last glacial maximum (LGM). It is found that the winter monsoon is remarkably stronger during the LGM than at present in the north part of China and the western Pacific but varies little in the south part of China. The summer monsoon remarkably weakens in South China Sea and the south part of China during the LGM and has no remarkable changes in the north part of China between the present and the LGM. Due to the alternations of the monsoons during the LGM, the annual mean precipitation significantly decreases in the northeast of China and the most part of north China and the Loess Plateau and the eastern QXP, which makes the earth surface lose more water and becomes dry, especially in the eastern QXP and the western Loess Plateau. In some areas of the middle QXP the decrease of evaporation at the earth surface causes soil to become wetter during the LGM than at present, which favors the water level of local lakes to rise during the LGM. Additionally, compared to the present, the depth of snow cover increases remarkably on the most part of the QXP during the LGM winter. The analysis of equilibrium line altitude (ELA) of glaciers on the QXP, calculated on the basis of the simulated temperature and precipitation, shows that although a less decrease of air temperature was simulated during the LGM in this paper, the balance between precipitation and air temperature associated with the atmospheric physical processes in the model makes the ELA be 300–900 m lower during the LGM than at present, namely going down from the present ELA above 5400 m to 4600–5200 m during the LGM, indicating a unified ice sheet on the QXP during the LGM.