末次冰盛期以来十年百年际亚洲季风气候变率与驱动机制

发布时间：2018-05-21 21:25

本文选题：冰盛期 + 神秘期　；参考：《南京师范大学》2015年博士论文

【摘要】：过去50万年来的高分辨率亚洲石笋6180记录详细刻画了亚洲季风的变化历史；明确了太阳辐射对季风变化的调控作用及对北半球冰盖消融的诱发作用；揭示了北高纬冰盖变化对千年尺度变化事件发生频率和持续时间的影响；证实了在相对稳定的全新世太阳活动是季风百年尺度变率的主控因素；已成为全球气候对比的基石之一。从末次盛冰期到冰消期再到全新世,地球气候经历了从全球冰盖最大到快速消融再到退缩到最小的三个完全不同的阶段。因此,系统地研究这3个阶段的气候变化过程有利于深入理解地球系统内部各要素如冰盖变化过程、大洋/季风环流重组与C02气体变化之间的耦合关系,为评估温室气体是否对气候变化产生影响提供理论依据；提取石笋多元气候指标有助于了解各气候要素的响应行为特征和准确理解突变气候的发生机制,还有利于评估和验证颇有争议的石笋δ180的气候意义。本文选取贵州省西南区域的程家春洞石笋同位素和南京葫芦洞石笋同位素和微量元素变化建立了从冰盛期到晚全新世平均分辨率为5.2 a的亚洲季风演化序列。CJC-1记录覆盖的时段为21.5-2.0 ka,δ18O的变化范围为-6.5‰～-14.5‰,波幅达到8‰；即使在相对稳定的全新世,波幅也达到5‰,与现代降水δ180的波幅一致。CJC-1δ18O与其他亚洲石笋记录的重现性说明CJC-1沉积时同位素达到平衡分馏,可用来重建古气候变化,较大的δ18O波幅说明对外界气候变化敏感。在盛冰期～19.5-17.5 ka时段,CJC-1和葫芦洞石笋都显示季风强度异常增强,达到B(?)lling-Allerod间冰阶水平,不同于盛冰期时季风减弱的模拟结果。此强季风事件与北大西洋温盐环流(AMOC)增强呈对应关系,说明海洋环流在盛冰期向欧亚大陆输送的热量足以引起季风增强。神秘期(17.5-14.5 ka)得名于在该时段内发生了一系列相互难以解释的气候现象。美国西南大湖盆在～16.1 ka由大干旱向大湿润转型的原因一直悬而未决。通过对发育有年纹层的葫芦洞石笋YT进行刀削法采样,发现δ18O在～16.1 ka于20 a内迅速偏正2‰,与ITCZ迅速南移的持续时间(17 a)相当。表明在～16.1ka发生的H1a冰漂碎屑事件导致全球水文循环发生重组,极地急流南移促使太平洋输送到美国西南部的水汽增加,从而引发北美西南大湖盆由大干旱转向大湿润。YT石笋的微量元素Sr/Ca和纹层厚度记录都在16.1 ka发生明显转折,且在百年-数十年尺度上与反映区域大尺度季风环流的δ18O记录有很好的对应关系,进一步支持了MI内部发生有低纬水文循环变化的过程和δ18O能够反映亚洲季风强度的解释。另一个神秘的气候事件是大气△14C在此3000 a的时间内下降幅度达到190±10‰。通过数理分析,我们发现亚洲季风强度、AMO C、南大洋蛋白石通量、大气CO2和△14C各记录在YD和MI两个时段的相对变化幅度的比值大致相等(～0.5),暗示了冰消期时大气和大洋环流的紧密耦合关系,表明AMOC驱动了全球CO2和大气△14C的变化,引起CO2和△14C变化的碳库为南大洋。在YD事件内部,CJC-1 δ18O和δ13C记录的4个百年尺度振荡与NGRIP冰芯记录有极好的对应关系。但是,在YD事件开始时CJC-1 δ18O和613C记录呈现出明显差异：CJC-1 δ13C与NGRIP δ18O享有相同的结构特征和持续时间；而CJC-1 δ18O记录的持续时间要长于NGRIP δ18O记录,与其他亚洲石笋δ18O记录一致。CJC-1 δ13C和NGIRP记录的对应性有助于避免石笋与冰芯之间的年龄时标差异来评估δ180指示的季风环流与格陵兰温度之间的相位关系。结果表明在YD事件开始时,季风环流减弱要早于格陵兰温度变化,表明YD事件并不是由AMOC变化触发的。从YD事件开始,石笋CJC-1 δ13C与NGRIP δ18O、全球冰量变化在长期趋势上有很好的对应关系。去趋势后CJC-1δ13C记录的百年尺度波动与北大西洋IRD以及8.2 ka事件、格陵兰温度和太阳活动有明显的对应性。此对应关系进一步支持了基于董歌洞石笋δ18O记录得出的北大西洋气候和太阳活动共同影响全新世东亚气候的理论,也说明石笋δ18O确实能够反映季风区的水文循环。本研究首次提供了一支从冰盛期到晚全新世长达20 ka的连续的高分辨率石笋同位素记录。通过结合南京葫芦洞石笋记录,探讨了神秘期美国西南部大湖盆由大干旱向大湿润转型、大气C02升高和△14C下降的原因；通过对比CJC-1与格陵兰同位素记录,明确地发现YD事件开始时亚洲季风环流的减弱过程要早于格陵兰温度的下降过程CJC-1 δ13C首次记录了北大西洋IRD事件,证实了北大西洋气候在全新世对东亚水文循环的影响。
[Abstract]:The high resolution Asian stalagmite 6180 records over the past 500 thousand years depicted the history of the Asian monsoon, the regulation of the solar radiation on the monsoon changes and the inducing effect on the melting of the ice cover in the northern hemisphere, and the influence of the change of the ice cover on the occurrence frequency and duration of the Millennium scale change events. The relatively stable Holocene solar activity is the main controlling factor of the Centennial variability of the monsoon. It has become one of the cornerstones of the global climate contrast. From the last glacial to the deglaciation to the Holocene, the earth's climate experienced three completely different stages from the maximum of the global ice cover to the rapid ablation to the minimum. The study of the 3 stages of climate change is beneficial to the understanding of the changes in the internal elements of the earth system, such as the changing process of ice cover, the coupling relationship between the ocean / monsoon circulation and the change of C02 gas, which provides a theoretical basis for assessing whether the greenhouse gases will affect the climate change. The characteristics of the response behavior of the climatic factors and the accurate understanding of the occurrence mechanism of the catastrophic climate are beneficial to the assessment and verification of the climatic significance of the controversial stalagmite delta 180. This paper selects the isotopes of the Stalagmite in the Cheng Jia Chun cave in the southwestern region of Guizhou and the changes of the stalagmite isotopes and trace elements in the Hulu cave of Nanjing from the ice flourishing period to the late brand new period. The period of Asian monsoon evolution sequence.CJC-1 recorded with an average resolution of 5.2 a was 21.5-2.0 Ka, and the range of delta 18O was -6.5 per 1000 to -14.5 per 1000, and the amplitude reached 8 per thousand. Even in the relatively stable Holocene, the amplitude reached 5 per thousand, and the recurrence of.CJC-1 [Delta] 18O and other Asian stalagmite records was consistent with the amplitude of the modern precipitation delta 180. During the deposition of CJC-1, the isotopes reached equilibrium fractionation and can be used to reconstruct the paleoclimate change. The larger Delta 18O amplitude is sensitive to the external climate change. In the period of the peak ice period to 19.5-17.5 Ka, the CJC-1 and the gourd cave stalagmites show the abnormal intensities of the monsoon intensity, reaching the level of the B (?) lling-Allerod, which is different from the model of the weakening of the monsoon during the glacial period. This strong monsoon event has a corresponding relationship with the North Atlantic warm salt circulation (AMOC) enhancement, indicating that the heat transported to Eurasia during the full ice period is enough to cause the monsoon enhancement. The mysterious period (17.5-14.5 KA) is named for a series of unexplained climate phenomena during this period. The Great Lake Basin in the southwest of the United States is 16.1. The reason for the transformation of Ka from great drought to great wetness has been unresolved. By cutting the YT of gourd Stalagmite in the gourd hole, which is developed with annual grain, it is found that delta 18O is quickly 2 per 1000 in ~ 16.1 Ka in 20 A, which is equivalent to the duration of the rapid migration of ITCZ (17 A). It shows that the H1a ice drifting event in 16.1ka causes the global hydrological cycle. The rapid southward migration of polar jets caused the Pacific to transport to the southwest of the United States to increase water vapor, causing the trace elements Sr/Ca and layer thickness of the.YT stalagmite from the great drought to the great humid North America and the 16.1 Ka, and on the scale of the Centennial to the decades to reflect the large scale monsoon circulation in the region. The delta 18O record has a good correspondence, which further supports the process of low latitude hydrological cycle changes in the MI and the interpretation of the Asian monsoon intensity. Another mysterious climate event is that the atmospheric Delta 14C is down to 190 + 10 per thousand within the time of this 3000 a. Through mathematical analysis, we found the Asian monsoon intensity. AMO C, the Southern Ocean opal flux, the ratio of the atmospheric CO2 and delta 14C records to the relative amplitude of the two periods of YD and MI are approximately equal (~ 0.5), suggesting the close coupling relationship between the atmosphere and the ocean circulation during the period of the deglaciation, indicating that AMOC drives the global CO2 and atmospheric Delta 14C changes, and that the carbon Library of CO2 and delta 14C changes is in the South Ocean. Within the D event, the 4 Centennial oscillations of the CJC-1 Delta 18O and delta 13C records have an excellent correspondence with the NGRIP ice core records. However, the CJC-1 Delta 18O and 613C records at the beginning of the YD event show obvious differences: CJC-1 Delta 13C has the same structural characteristics and duration as NGRIP Delta, while the duration of the delta record is longer than that of the YD event. The GRIP Delta 18O record, and the correspondence between the.CJC-1 Delta 13C and NGIRP records consistent with the other Asian stalagmite Delta 18O records, helps to avoid the age time difference between the stalagmite and the ice core to assess the phase relationship between the monsoon circulation and Greenland temperature indicated by delta 180. The result indicates that the weakening of the monsoon circulation at the beginning of the YD event is earlier than Greenland temperature. The degree change indicates that the YD event is not triggered by the change of AMOC. From the beginning of the YD event, the CJC-1 Delta 13C and NGRIP Delta 18O, the global ice change has a good relationship with the long-term trend. After detrending, the 100 year scale fluctuation of the CJC-1 Delta 13C record is obvious to the North Atlantic IRD and 8.2 Ka, Greenland temperature and solar activity. This corresponding relationship further supports the theory that the North Atlantic climate and solar activity have a common influence on the climate of the Holocene in the North Atlantic, which is based on the delta 18O record of Dong song stalagmites. It also indicates that the stalagmite Delta 18O can indeed reflect the hydrological cycle of the monsoon region. This study provides the first time from the glacial to the late Holocene to a 20 Ka continuum. High resolution isotopic records of high resolution stalagmite were recorded. By combining the record of Stalagmite in Nanjing Hulu cave, the causes of the transition from great drought to great wetness in the Great Lake Basin in the southwest of the United States, the increase of atmospheric C02 and the decrease of delta 14C were discussed. By contrasting CJC-1 and Greenland isotopic records, the Asian monsoon circulation was weakened clearly at the beginning of the occurrence of the occurrence of the YD event. CJC-1 Delta 13C, which was first recorded in the North Atlantic IRD event earlier than the decline of Greenland temperature, confirmed the influence of the North Atlantic climate on the hydrological cycle of the East Asia in the Holocene.
【学位授予单位】：南京师范大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P532

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