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黄土高原260万年以来东亚夏季风演变信号研究
引用本文:薛根元,周锁铨,陈旸,郦敏捷,陈红梅,全利红.黄土高原260万年以来东亚夏季风演变信号研究[J].气候与环境研究,2007,12(1):63-73.
作者姓名:薛根元  周锁铨  陈旸  郦敏捷  陈红梅  全利红
作者单位:1. 南京信息工程大学,南京,210044;浙江省气象局,杭州,310002
2. 南京信息工程大学,南京,210044
3. 南京大学表生地球化学研究所成矿作用国家重点实验室,南京,210009
4. 浙江省杭州市气象局,杭州,310008
5. 浙江省绍兴市气象局,绍兴,312000
6. 中国科学院大气物理研究所,北京,100081
基金项目:国家重点基础研究发展计划(973计划);国家自然科学基金
摘    要:在研究黄土高原东亚季风地质时期周期演变中,引入了用于定量检测周期的奇异谱分析方法,结合小波分析,对典型的黄土高原陕西省洛川黄土剖面、甘肃省灵台黄土剖面的磁化率中2.6 MaB.P.以来东亚季风的强信号进行了研究。结果表明:2.6-1.0 MaB.P.之间地质时期,除在1.87-1.37 MaB.P.之间可能存在一个周期演变不明显的缺失时段外,东亚季风演变的主导周期是40 ka,0.9-0.6 MaB.P.是40 ka周期和100 ka周期的调整过渡期。0.6 MaB.P.以来的主导周期是100ka。研究还发现,1.2 MaB.P.前后没有明显的周期差异,说明1.2 MaB.P.不是一次真正意义上的周期转型事件,而是周期演变过程中的触发事件,这一触发事件对0.9 MaB.P.以后出现的周期转型事件影响深刻。40 ka周期从1.2 MaB.P.开始衰减,至0.9MaB.P.时100 ka周期逐渐建立。0.6 MaB.P.开始东亚季风出现冷暖大幅振荡的100 ka演变周期,因而0.6MaB.P.具有气候振荡加剧的突变性质。

关 键 词:小波分析  奇异谱分析  黄土  磁化率  东亚季风
文章编号:24354042
修稿时间:05 23 2005 12:00AM

Significant Spectrum Evolution of the East Asian Summer Monsoon on the Loess Plateau During the Last 2.6 MaB.P.
XUE Gen Yuan,ZHOU Suo Quan,CHEN Yang,LI Min Jie,CHEN Hong Mei and QUAN Li Hong.Significant Spectrum Evolution of the East Asian Summer Monsoon on the Loess Plateau During the Last 2.6 MaB.P.[J].Climatic and Environmental Research,2007,12(1):63-73.
Authors:XUE Gen Yuan  ZHOU Suo Quan  CHEN Yang  LI Min Jie  CHEN Hong Mei and QUAN Li Hong
Affiliation:1 .Nanjing University of Information Science and Technology, Nanjing 210044 ;2. State Key Laboratory of Mineral Deposit Research, Institute of Surficial Geochemistry, Departrnentof Earth Sciences, NanjingUniversity, Nanjing 210093 ;3. Meteorological Bureau of Zhejiang Province, Hangzhou 310002 ;4 .Meteorological Burean of Hangzhou in Zheijiang Province, Hangzhou 310008 ;5 .Meteorological Bureau of Shaoxing in Zhejiang Province, Shaoxing 312000 ;6 .Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100081
Abstract:The loess-paleosol sequence in central China is regarded as an excellent continental record of palaeoclimatic and palaeoenvironmental changes during the Late Cenozoic era.The alternation of paleosol and loess units is commonly interpreted as an indication of alternating waxings and wanings of the paleomonsoon in the East Asia,with the soil-forming periods corresponding to strengthened summer monsoon and loess deposition to strengthened winter monsoon.Previous studies investigated orbital cycles(100,41,21 and 19 ka) of the East Asian monsoon variation recorded in the loess-paleosol sequences,however,discrepancies persist about other non-orbital cycles(66,57,35 and 31 ka,etc),the time that 100-ka cycle appeared and the interval that 100-ka cycle dominated,due to different proxies used,different time scale models established and different spectral analyses applied.Wavelet transform and Singular Spectrum Analysis(SSA) are powerful and quantitative methods of spectral analysis for time series,the former can provide flexible localized time-frequency information,and the latter can give estimates of statistical dimension and divide the time series into principle components.In this study,SSA and the wavelet analysis are used to determine the periodicity of the East Asian monsoon evolution on the Chinese loess plateau quantitatively.Magnetic susceptibility(MS),an indicator of the East Asian summer monsoon intensity,is determined in the loess-paleosol sequences over the last 2.6 Ma from the typical loess sections at Luochuan,Shaanxi province,and Lingtai,Gansu province,respectively.The time series of MS are established using the time scale model derived from relationship between Rb-concentration and sedimentation rate.Then the significant evolution cycles of the East Asian summer monsoon are extracted and can be verified within the two sections.The results show that: (1) There are three stages of the evolution of the East Asian summer monsoon during the past 2.6 MaB.P.1) 2.5-1.0 MaB.P.,40-ka cycle is dominant except that there may be no significant cycles during the 1.87-1.37 MaB.P.interval,reflecting orbital forcing on the summer monsoon variation;2) 0.9-0.6 MaB.P.,a transition period from 40-ka cycle to 100-ka cycle;3) 0.6-0 MaB.P.,100-ka cycle is dominant,indicating possible influence from low-latitude oceans on the summer monsoon evolution through the adjustment from global carbon cycle or atmospheric CO2 content.(2) There is no obvious change of cycles around 1.2 MaB.P.It indicates that 1.2 MaB.P.is not a real transition time of climatic cycles,but a trigger time for the evolution of cycles in the summer monsoon.This trigger event may be driven by the Kulun-Yellow River movement occurring in 1.2 MaB.P.and affect greatly on the cycle transition between 0.9-0.6 MaB.P.(3) Both wavelet analysis and SSA give the consistent results that 40-ka cycle begins to weaken from 1.2 MaB.P.and breaks down from 0.9 MaB.P.while 100-ka cycle has gradually generated since 0.9 MaB.P.The East Asian summer monsoon begins to evolve into greatly warm/cool fluctuations dominated by 100-ka cycle since 0.6 MaB.P.Therefore,0.6 MaB.P.is the time that the summer monsoon climate has abrupt changes with large amplitude of fluctuations.
Keywords:wavelet analysis  singular spectrum analysis  loess plateau  magnetic susceptibility  evolution cycles of the East Asian summer monsoon
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