第四纪古气候变化非线性动力学初步研究——黄土粒度曲线的奇异谱分析  

A STUDY ON NONLINEAR DYNAMICS OF PALEOCLIMATE VARIATIONS DURING QUATERNARY:SINGULAR SPECTRUM ANALYSIS OF LOESS GRAIN-SIZE RECORD

作　　者：余志伟[1] 丁仲礼[2] 刘东生[2] 

机构地区：[1]中国矿业大学地质系 [2]中国科学院地质研究所

出　　处：《第四纪研究》1993年第3期214-230,共17页Quaternary Sciences

基　　金：国家自然科学青年基金

摘　　要：作者将奇异谱分析(SSA)引入第四纪古气候变化研究中,收到了较好的效果。奇异谱分析是一种新的时间序列分析工具,它可形成一个单边(向前)滤波器,将原时间序列有效地分解成各个主成分,其滤波系数完全由数据本身决定。由奇异谱分析确定的统计维,给出动力维上界的估计,为非线性动力学研究打下基础。分析表明,在整个第四纪,宝鸡黄土粒度曲线的统计维为19,与深海钻孔V28-239氧同位素分析结果(=18)十分接近;各主成分在地球轨道几何参数各成分中大都能找到对应关系,但均不是线性响应关系;与偏心率、地轴倾斜度和岁差有关的成分分别占46、43和6％左右;其中第一主成分还揭示出与偏心率约0.4Ma周期对应的振荡仅在2.5—1.7和0.7—0.3Ma B.P.出现。The authors regard the Baoji loess grain-size time series, generated by employing orbital tuning approach by SPECMAP project, as a proxy of paleoclimatic variations during the Quaternary and apply Singular Spectrum Analysis (SSA) to investigate the dynamic characteristics of paleoclimate and lay foundations for nonlinear dynamics study in this field. SSA provides estimates of the statistical dimension, which gives a theoretical upper boundary for the minimal number of degrees of freedom required to describe the attractor of a dynamic system. It also gives time-domain moving-average filters determined directly by the data by means of solving eigenvectors of the embedding matrix, so that we can effectively divide the time series into principal components (PCs). The percentage of every eigenvalue out of all the eigenvalues reflects the relative weight of the PC. Those PCs describe the main physical phenomena reflected by the data and the regime changes of the dynamic system. It turns out that SSA is a new and powerful spectrum analysis for time series and a powerful descriptive tool for nonlinear dynamics in general and climate dynamics in particular. We have investigated the Baoji loess grain-size record, i.e. the profile of radio <2μm％ to >10μm％, which is considered to he a proxy indicator of winter monsoon strength. Data are sampled at a regular depth interval of 10 cm, containing 1587 raw points and corresponding to unequal time intervals. To obtain uniform samling in time, the techniques of orbital tuning approach developed by SPECMAP project is employed, followed by interpolation of the data to the new time scale. For this time series, the mean has been subtracted and the values normalized by its standard deviation. We apply this apparatus to two time spans,0.8—0.0 and 2.5—0.0 MaB.P., of Baoji grain-size time series respectively. The results are as follow: (1) 0.8—0.0 Ma. B.P. Fig. 1 shows the singular spectra for M(embedding dimension)=10,20 and 40; the corresponding window lengths (τ_w) are

关 键 词：第四纪 古气候 非线性动力学 黄土 粒度 

分 类 号：P532[天文地球—古生物学与地层学]