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越来越多的资料证实,从第四纪和第三纪晚期到大约900ka前的中更新世转变前(MPT,mid-Pleistocene transition),北半球冰期变化周期为40ka,MPT之后转变为100ka.一般作为外强迫来解释冰期间冰期循环的北半球中高纬度夏季太阳辐射变化是由地球轨道进动控制的,但其主要周期是20ka,这和实际的冰期间冰期循环的周期不相符.定义了一个能量指标C和响应阈值Ct,前者表示外部辐射能量的供给大小,后者代表了气候系统的整体响应.C与Ct的大小关系决定冰原融化或者积累,控制间冰期的开始和结束的时间,并决定冰期循环的周期.基于能量阈值假设,从一个概念模式出发对冰期循环周期和控制因子进行了模拟试验.结果显示,能量指标C和阈值Ct不仅能够解释中更新世转变之前冰期的40ka周期变化,也能够部分地解释MPT之后冰期的准100ka周期变化,其中40ka是冰期循环的基本周期,从而揭示了MPT前后气候系统变化和周期演变的内在连续性.
More and more data confirm that from the late Quaternary and the Tertiary to the pre-Pre-MPE (MPT) transition about 900ka, the period of the Northern Hemisphere ice age is 40ka and the MPT is changed to 100ka. As a result of external forcing to account for glacial ice cycles during the Northern Hemisphere mid-high latitudes Summer solar radiation changes are controlled by the precession of the Earth’s orbit, but its main period is 20 ka, which is not consistent with the actual ice period cycle. Energy index C and response threshold Ct, the former indicates the supply of external radiant energy, and the latter represents the overall response of the climate system.The relationship between C and Ct determines the melting or accumulation of ice sheets and controls the beginning and ending time of interglacials and Based on the assumption of energy threshold, a simulation experiment was conducted on the cycle and control factors of glacial period from a conceptual model.The results show that the energy index C and the threshold Ct can not only explain the 40ka cycle change in the glacial period before the mid-Pleistocene transition , It is also possible to explain, in part, the quasi-100ka periodic variation of the glacial phase after MPT, where 40ka is the basic cycle of the glacial cycle, thus revealing Inherent Continuity of Climate System Change and Periodic Evolution before and after MPT.