基于EEMD方法的全新世亚洲季风石笋氧碳同位素对比研究  

Comparison of oxygen-carbon isotopes from a Holocene stalagmite by EEMD method

作　　者：杨少华[1,2,3] 陈仕涛[1,2,3] 汪永进[1,2,3] 张振球[1,2,3] 曾雅兰[1,2,3] 

机构地区：[1]南京师范大学地理科学学院,虚拟地理环境教育部重点实验室,南京210023 [2]江苏省地理环境演化国家重点实验室培育建设点,南京210023 [3]江苏省地理信息资源开发与利用协同创新中心,南京210023

出　　处：《地理研究》2017年第8期1455-1466,共12页Geographical Research

基　　金：国家自然科学基金项目(41130210,41572340);江苏高校优势学科建设工程资助项目(164320H116)

摘　　要：采用集合经验模态分解方法(EEMD),对贵州省董哥洞全新世石笋δ^(18)O、δ^(13)C记录进行多尺度分解,分别获得8、9个本征模分量。在254 a以下尺度上,石笋δ^(13)C和δ^(18)O的本征模分量基本一致,其中254 a和116 a两个周期都类似于大气Δ^(14)C表征的太阳活动周期,表明植被生产力和低纬水汽都受控于太阳活动。同一周期对应的δ^(13)C振幅几乎是δ^(18)O的2倍,说明洞穴地点的土壤生产率放大了太阳活动的初始信号。526 a周期对石笋δ^(13)C贡献最大(~20%),与北大西洋深层水体550 a周期一致,可能的机制是北半球高纬气候通过西风带影响了东亚大陆的环境变化。石笋δ^(13)C的趋势分量变化平稳,明显不同于δ^(18)O的趋势分量,表明洞穴地点的土壤生产率并不直接响应于轨道尺度的太阳辐射变化。The connection between Asian summer monsoon and northern high-latitude climate and solar forcing during the Holocene has been reported by the oxygen isotope records from Dongge cave, Guizhou province, China. In this paper, time series of carbon isotope from this stalagmite were reanalyzed via the ensemble empirical mode decomposition（EEMD）. The decomposed results, intrinsic mode function, indicated three main time scale changes, e.g. interdecadal（imfc1-imfc3）, centennial scale（imfc4-imfc6） and millennial scale（imfc7-imfc9）. The δ^（13）C values reflect the types and density of vegetation and the production of soil CO2 above the cave. Discrepancies and similarities both occur between δ^（13）C and δ^（18）O time series. At centennial to decadal scales, both isotopic records are closely coupled, among which the periodicities of 254 a and 116 a agree well with the atmospheric Δ^（14）C（proxy for solar activity）, denoting both soil CO2 and the hydrologic circulation of low latitudes were controlled by solar activity. This relationship is further confirmed by the analysis of cross wavelet spectrum between the stalagmite δ^（13）C values and the detrended atmospheric Δ^（14）C. The contribution of the imfc6 component is the highest, which presents a quasi-periodicity variability of 526 a, and is similar to the 550 a periodicity of the North Atlantic Deep Water formation, denoting a teleconnection between the carbon isotope variation and the environment change of the northern high latitude region. The trend of δ^（13）C variations is significantly different from δ^（18）O record, suggesting the production of soil CO2 is not influenced directly by the change of solar irradiation. EEMD results show that the amplitude of imfc is about twice of IMFo in the same cycle, which means that the stalagmite δ^（13）C may be more sensitive to climate changes than the δ^（18）O. Hence, the δ^（13）C signal can be more suitable for the study of the relationship between solar activit

关 键 词：集合经验模态分解(EEMD) 全新世 亚洲季风 石笋碳同位素 

分 类 号：P532[天文地球—古生物学与地层学]