SIMULATION OF ABRUPT CLIMATE CHANGE IN EASTERN ASIA DURING YOUNGER DRYAS
Chen Xing Yu Ge Liu Jian(Department of Atmospheric Sciences, Nanjing University, Nanjing 210093;Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences , Nanjing 210008)
The abrupt climatic change event- Younger Dryas (YD) marks a rapid decreasing in global temperature, with average temperature dropping. The purpose of this study is to explore the possible causes and mechanisms of YD in eastern Asia by using global climate models. With our modeling approaches some sensitive simulations are carried out for verifying some hypothesis of the proposed causes of YD and to find potential physical and dynamical factors that contributed to the YD climate change in eastern Asia. The modeling results indicated that the melt fresh water from ice sheet is the direct extra forcing factor for YD climate change. The interaction and coupling between ocean and atmosphere and its intensity are important for the strength of propagating and time lag of YD from European to eastern Asia. Besides the melt fresh water from the northern Atlantic, the melt fresh water from Antarctic in the Southern Hemisphere may have played the same important role for the YD climate in eastern Asia. From coupled climate model ECHO-G, under the condition with inner oscillation of ocean-atmosphere, decreasing in temperature in eastern Asia is about two years lagging comparing with that in Europe. The maximum variability of temperature are -0.122℃/a in Europe and -0.067℃/a in eastern Asia, respectively. The climatic features from our modeling results are comparable to that from climatological records during the YD in eastern Asia. It suggests that the experimental design and the forcing fields in the simulation are close to the paleoclimate condition of YD in eastern Asia. Therefore, our simulated study is useful in understanding and exploring the physical and dynamical causes of YD and the interaction among ocean, ice sheet and atmosphere under such an extreme climatic condition.