CLIMATIC DYNAMICS FOR 6 kaBP VEGETATIONAL CHANGES IN ASIAN MONSOON REGION

Pollen-based reconstruction of palaeovegetation at 6 kaBP shows that the broad-leaved evergreen and deciduous forest zones as well as the mixed needle-leaved and deciduous forest zone expanded successively northwards to a large extent when compared with the present in China, suggesting a warmer-than-present winter and summer in China. However, the warming event during the 6 ka BP winter can not be proved on the basis of the orbit-forcing climate simulations at 6 ka BP because the simulations have witnessed a lower insolation than present in winter season in the low and middle latitudes of the Northern Hemisphere. This discrepancy indicates that the climatic dynamics can not be solely predicated by the orbit-forcing mechanism. A climate modeling with land processes (AGCM+SsiB) is thus used to explore the issues of the palaeoclimates. The simulation by the climate model with land surface processes as main factors can simulate the changes in temperature at 6 kaBP that increased both in summer and winter, and is in good agreement with pollen data. The preliminary results of the modeling demonstrated that land surface feedback in Asian monsoon region had played an important role.

Project Supported:

Clc Number:

P532 Q914.5