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黄土磁化率可用以指示夏季风强度,并已在中国风尘堆积的古气候演化周期研究中得到较好应用,但迄今多集中于东南季风区.以青藏高原东南缘甘孜A黄土剖面磁性地层学研究为基础,对1.16Ma以来的磁化率记录进行经验模态分解(EMD),探讨西南季风演化的多时间尺度周期性.结果表明:偏心率、地轴倾斜、岁差的准周期成分在西南季风区黄土沉积中有明显反映,指示西南季风的演化受天文因素控制;出现岁差的拍频周期,指示印度季风系统具有热带特征;准200ka周期是真实存在的,但其成因机制需要进一步研究;约400ka周期波动,可能对应理论值为准400ka的偏心率长周期.西南季风演化的主要驱动因素可能是低纬太阳辐射.对于沉积记录的周期性研究来讲,经验模态分解更切合实际,它比传统谱分析方法有明显的优势和应用潜力.
The magnetic susceptibility of loess can be used to indicate the intensity of the summer monsoon and has been well applied in the study of paleoclimate evolution cycles of dust accumulation in China so far, but it is mainly concentrated in the southeast monsoon region. Based on the magnetic stratigraphy of the Garze A Loess Plateau in the southeastern margin of the Qinghai- (EMD) of magnetic susceptibility records since 1.16Ma, and discuss the multi-time scale periodicity of southwest monsoon evolution.The results show that the eccentricity, The evolution of the southwest monsoon is controlled by the astronomical factors. The beating period of the precession indicates that the Indian monsoon system has tropical characteristics. The quasi 200ka period is real, but its mechanism needs further study. The period of about 400 ka Which may correspond to the long period of eccentricity with the theoretical value of 400 K. The main driving force for the evolution of the southwestern monsoon may be the low latitude solar radiation.The empirical mode decomposition is more realistic for the periodic study of sedimentary records than traditional Spectral analysis has obvious advantages and potential applications.