Interpretation and preliminary simulation of the 40 ka periodicity of the Quaternary glaciation  

作　　者：LI Nan CHEN Xingt 

机构地区：[1]Department of Atmospheric Sciences, Nanjing University, Nanjing 210093, China

出　　处：《Chinese Science Bulletin》2007年第16期2275-2284,共10页

基　　金：Supported by the National Natural Science Foundation of China (Grant No. 40475035);the National Basic Research Program of China (Grant No. 2006CB400500)

摘　　要：More and more proxy records approved that the periodicity of the glacial cycles is about 40 ka before MPT (middle Pleistocene transition) as early as late Tertiary from 3.0 Ma to 0.9 Ma,whereas it changes to about 100 ka after MPT. Summer insolation at high latitude in Northern Hemisphere,usually consid-ered as the main external force for the ice age,is dominated by the 23 ka precession period,which does not match the period of the glacial cycles. In this paper,we define an energy index C and its threshold Ct that indicate the net energy supply and the overall response of the climate system. The difference between these two parameters determines whether the ice sheet melts or not,and accordingly the start and termination of the interglacial stages,as well as the periodicity of glacial oscillations. Based on the energy threshold hypothesis,the preliminary simulation experiments are made to test the period of the glacial cycles and driven factors from a conceptual model. The results indicate that energy index C and threshold Ct can interpret not only the 40 ka periodicity before MPT,but also the quasi-100 ka perio-dicity after MPT to some extent,and the 40 ka is the basic period of the glacial cycles,which discloses the inherent continuity of climatic change before and after MPT.More and more proxy records approved that the periodicity of the glacial cycles is about 40 ka before MPT （middle Pleistocene transition） as early as late Tertiary from 3.0 Ma to 0.9 Ma, whereas it changes to about 100 ka after MPT. Summer insolation at high latitude in Northern Hemisphere, usually considered as the main external force for the ice age, is dominated by the 23 ka precession period, which does not match the period of the glacial cycles. In this paper, we define an energy index C and its threshold Ct that indicate the net energy supply and the overall response of the climate system. The difference between these two parameters determines whether the ice sheet melts or not, and accordingly the start and termination of the interglacial stages, as well as the periodicity of glacial oscillations. Based on the energy threshold hypothesis, the preliminary simulation experiments are made to test the period of the glacial cycles and driven factors from a conceptual model. The results indicate that energy index C and threshold Ct can interpret not only the 40 ka periodicity before MPT, but also the quasi-100 ka periodicity after MPT to some extent, and the 40 ka is the basic period of the glacial cycles, which discloses the inherent continuity of climatic change before and after MPT.

关 键 词：第四纪 冰川作用 米兰柯维奇理论 周期性 太阳暴晒 

分 类 号：P343.6[天文地球—水文科学]