The increase in the global average temperature during the last century is considered an integrated result of anthropogenic and natural forcing, but different views remain about the anthropogenic impacts on the Asian m...The increase in the global average temperature during the last century is considered an integrated result of anthropogenic and natural forcing, but different views remain about the anthropogenic impacts on the Asian monsoon precipitation. Based on the ~2000-year records of stalagmite δ18O from the Dongge Cave (Guizhou Province) and Wanxiang Cave (Gansu Province), we address the possible anthropogenic impacts on the southwest and southeast Asian monsoon from 1900-2000 AD, using the method of Singular Spectrum Analysis (SSA). The results show that the monsoon precipitation trends in the last 100 years at both sites can be obtained through SSA prediction using the data prior to 1900 AD. These suggest that human activity has not significantly affected the trends of monsoon precipitation despite of its impact on the global temperature.展开更多
研究晚全新世季风气候演变有助于进一步认识与预测未来季风区气候变化。太平洋东西两岸是全球季风集中分布的地区,已经有大量的古气候记录发表,但是缺乏对各个季风区气候突变事件以及整体变化趋势的对比研究。针对这一问题,选取亚洲季...研究晚全新世季风气候演变有助于进一步认识与预测未来季风区气候变化。太平洋东西两岸是全球季风集中分布的地区,已经有大量的古气候记录发表,但是缺乏对各个季风区气候突变事件以及整体变化趋势的对比研究。针对这一问题,选取亚洲季风区、印澳季风区、北美季风区、南美季风区11个洞穴石笋δ18O和1个湖泊Ti含量,对比研究各个记录在3.5~0.5 ka B.P.期间指示的夏季风变化特征。通过对比发现四大季风区的石笋δ18O在晚全新世整体上呈现偏正趋势,指示夏季风减弱;2次重要的气候突变事件1.5 ka B.P.和2.7 ka B.P.弱夏季风事件在各个季风区内均有表现;同时也记录了一系列十年际-百年际尺度的弱夏季风事件,表明太平洋东西两岸和南北半球的夏季风都有减弱的趋势,这与先前研究认为的南北半球呈现"see-saw"模式表现出不一样的特征。晚全新世以来ENSO(El Nino-Southern Oscillation)活动的增强对太平洋东西两岸南北半球夏季风减弱具有重要影响。在El Nino事件发生时,Walker环流减弱,而且它的上升支向东移动远离西太平洋暖池,西太平洋副热带高压增强并向西移动,导致亚洲夏季风减弱。Walker环流的东移也会使得印度尼西亚-太平洋暖池(Indo-Pacific Warm Pool,简称IPWP)海温下降,热带季节内震荡减弱致使印澳夏季风减弱;此外,El Nino事件发生时,赤道东太平洋海水温度上升导致东西太平洋海水温度梯度减弱,在此状态下南美季风区低空急流(Low Level Jet,简称LLJ)减弱,导致南美夏季风减弱;同时,北美洲加勒比海低空急流增强,使得该季风区下沉气流增强,导致北美夏季风减弱。我们的研究表明,在晚全新世ENSO活动增强的状态下,太平洋东西两岸南北半球夏季风变化可能都呈现减弱趋势。展开更多
文章基于山西黎城白云洞高分辨率石笋(BY2)δ^18O记录,重建了53.82~47.41 ka B.P.东亚夏季风演化历史.BY2δ^18O值在52.2 ka B.P.和49.5 ka B.P.前后显著偏负,指示两次夏季风显著增强阶段,分别对应于格陵兰冰芯记录的DO14和DO13事件.山...文章基于山西黎城白云洞高分辨率石笋(BY2)δ^18O记录,重建了53.82~47.41 ka B.P.东亚夏季风演化历史.BY2δ^18O值在52.2 ka B.P.和49.5 ka B.P.前后显著偏负,指示两次夏季风显著增强阶段,分别对应于格陵兰冰芯记录的DO14和DO13事件.山西白云洞石笋清晰记录了CIS13事件"双峰"结构,与NGRIP冰芯记录相对应,反映了东亚季风边缘区对北大西洋海-气耦合振荡,以及ITCZ南北移动引起的雨带范围变化的敏感响应.但BY2δ^18O记录的CIS13事件转换过程较NGRIP缓慢,其中开始过程呈现"三相位"变化特征:即亚洲夏季风提前出现缓慢增强趋势、在达到水热阈值条件后表现出与格陵兰温度的同步快速爆发、 最后仍持续增强直至峰值;这与热带大西洋和印度洋海盆岩芯反照率记录相似,可能与南大洋越赤道气流以及ITCZ持续北移有关.另一方面,千年尺度事件和百年-年代际振荡幅度分别高达5‰和2‰,明显较东亚季风区其他石笋 δ^18O记录大,尤其是在百年-年代际尺度上呈现出"高频、大幅"的变化特征;表明其敏感响应于不同时间尺度气候波动.功率谱结果表明,其具有明显的50 a、60 a和206 a变化周期,可能受到太阳活动和海洋水文变化的双重影响.展开更多
The causal correlation or linkage between the East Asian Monsoon (EAM) intensity and rise/fall of Chinese dynasties recently proposed by high-resolution paleoclimate reconstructions is examined in detail. Aside from m...The causal correlation or linkage between the East Asian Monsoon (EAM) intensity and rise/fall of Chinese dynasties recently proposed by high-resolution paleoclimate reconstructions is examined in detail. Aside from many exceptions to the correlation, both instrumental and historical climate records show strong spatial variations of rainfall on annual-to-decadal scales over eastern China. The relationship between rainfall and EAM intensity also exhibits regional disparity. These observations suggest: (1) Tak-ing paleo-proxy records from a single locality in eastern China to imply changes in drought/wetness as to affect the cultural and political history of China is fraught with uncertainty. (2) On annual-to-decadal scales, the thesis that δ18O in speleothems can be used as a proxy for the EAM strength lacks empirical underpinnings.展开更多
Occurrence or absence of centennial-scale climatic variability during Marine Isotope Stage(MIS)7e,the first peak interval of the Penultimate Interglacial,remains ambiguous due to the limited available high-resolved re...Occurrence or absence of centennial-scale climatic variability during Marine Isotope Stage(MIS)7e,the first peak interval of the Penultimate Interglacial,remains ambiguous due to the limited available high-resolved records.Here,we present a decadal-resolved stalagmiteδ^(18)O record from northern China spanning from 242.3 to 236.8 ka BP,covering MIS7e.The composite KLSδ^(18)O record,integrating this study with the previous record in the same cave,shows a descending trend from TerminationⅢto MIS7e,which follows the increasing Northern Hemisphere summer insolation(NHSI).This observation further emphasizes the important influence of NHSI on the glacial/interglacial transition.There are more large-amplitude,millennial-to centennial-scale variability occurring during TerminationⅢcompared with MIS7e,implying that ice-sheet decay potentially plays an important role in climatic excursions.Four centennial-scale summer monsoon collapses,peaking at~242.1,~240.8,~239.3 and~238.2 ka BP,are detected in our new record,indicating the pervasiveness of the intra-interglacial climatic instability.Given the lack of solar activity and freshwater outbursts data during MIS7e,it is not possible to conclude about the drivers of the identified abrupt climatic anomalous.Following the dynamic mechanisms of sub-millennial climatic anomalous during early Holocene,we tentatively propose that slowdown of the meridional overturning circulation caused by freshwater fluxes into North Atlantic and/or attenuated solar irradiance is the potential forcing for the abrupt climate events within MIS7e.Additionally,attenuated solar irradiance could also result in climatic anomalies through low-latitude processes.展开更多
近些年,对于东亚季风区石笋δ^(18)O的气候环境指示意义的争论较多,主要在东亚季风区石笋δ^(18)O代表夏季和风强度、夏季风降水还是水汽源变化。基于中国东部华北地区降水与长江中下游地区降水反相变化和长江中下游地区降水与菲律宾海...近些年,对于东亚季风区石笋δ^(18)O的气候环境指示意义的争论较多,主要在东亚季风区石笋δ^(18)O代表夏季和风强度、夏季风降水还是水汽源变化。基于中国东部华北地区降水与长江中下游地区降水反相变化和长江中下游地区降水与菲律宾海降水反相变化(遥相关),从年际-年代际到千年-轨道尺度对石笋δ^(18)O与夏季风降水、厄尔尼诺-南方涛动(ENSO)的相互关系进行了探讨分析。通过对比石笋δ^(18)O记录与华北和梅雨区降水,发现石笋δ^(18)O偏负对应华北降水增加,梅雨区降水减少;石笋δ^(18)O偏正对应华北降水减少,梅雨区降水增加。这种对应关系不仅存在年际-年代际尺度,而且在千年-轨道尺度同样存在,石笋δ^(18)O不仅反映夏季风强弱变化,同时与中国东部区域降水关系是明确对应的。通过降水的空间相互关系,发现ENSO活动主要通过影响中国东部降水的空间分布格局而作用于石笋δ^(18)O。La Ni a态导致南海及菲律宾海对流加强,西太副高位置偏北,长江中下游地区梅雨期缩短,华北夏季降水增加,东亚季风区石笋δ^(18)O偏负。El Ni o态,南海和菲律宾海对流受到抑制,西太副高位置南移,长江中下游地区梅雨期延长,华北夏季降水减少,东亚季风区石笋δ^(18)O偏正。另外,水汽源分析发现,菲律宾海水汽输送对东亚季风区降水及降水δ^(18)O贡献相对较小。因此,综合分析认为,东亚季风区石笋δ^(18)O主要反映了亚洲夏季风的强弱变化。展开更多
基金supported by Chinese Academy of Sciences (Grant Nos.KZCX2-YW-Q1-15 and KZCX2-YW-117)National Natural Science Foundation of China (Grant No.40730104)
文摘The increase in the global average temperature during the last century is considered an integrated result of anthropogenic and natural forcing, but different views remain about the anthropogenic impacts on the Asian monsoon precipitation. Based on the ~2000-year records of stalagmite δ18O from the Dongge Cave (Guizhou Province) and Wanxiang Cave (Gansu Province), we address the possible anthropogenic impacts on the southwest and southeast Asian monsoon from 1900-2000 AD, using the method of Singular Spectrum Analysis (SSA). The results show that the monsoon precipitation trends in the last 100 years at both sites can be obtained through SSA prediction using the data prior to 1900 AD. These suggest that human activity has not significantly affected the trends of monsoon precipitation despite of its impact on the global temperature.
文摘研究晚全新世季风气候演变有助于进一步认识与预测未来季风区气候变化。太平洋东西两岸是全球季风集中分布的地区,已经有大量的古气候记录发表,但是缺乏对各个季风区气候突变事件以及整体变化趋势的对比研究。针对这一问题,选取亚洲季风区、印澳季风区、北美季风区、南美季风区11个洞穴石笋δ18O和1个湖泊Ti含量,对比研究各个记录在3.5~0.5 ka B.P.期间指示的夏季风变化特征。通过对比发现四大季风区的石笋δ18O在晚全新世整体上呈现偏正趋势,指示夏季风减弱;2次重要的气候突变事件1.5 ka B.P.和2.7 ka B.P.弱夏季风事件在各个季风区内均有表现;同时也记录了一系列十年际-百年际尺度的弱夏季风事件,表明太平洋东西两岸和南北半球的夏季风都有减弱的趋势,这与先前研究认为的南北半球呈现"see-saw"模式表现出不一样的特征。晚全新世以来ENSO(El Nino-Southern Oscillation)活动的增强对太平洋东西两岸南北半球夏季风减弱具有重要影响。在El Nino事件发生时,Walker环流减弱,而且它的上升支向东移动远离西太平洋暖池,西太平洋副热带高压增强并向西移动,导致亚洲夏季风减弱。Walker环流的东移也会使得印度尼西亚-太平洋暖池(Indo-Pacific Warm Pool,简称IPWP)海温下降,热带季节内震荡减弱致使印澳夏季风减弱;此外,El Nino事件发生时,赤道东太平洋海水温度上升导致东西太平洋海水温度梯度减弱,在此状态下南美季风区低空急流(Low Level Jet,简称LLJ)减弱,导致南美夏季风减弱;同时,北美洲加勒比海低空急流增强,使得该季风区下沉气流增强,导致北美夏季风减弱。我们的研究表明,在晚全新世ENSO活动增强的状态下,太平洋东西两岸南北半球夏季风变化可能都呈现减弱趋势。
文摘文章基于山西黎城白云洞高分辨率石笋(BY2)δ^18O记录,重建了53.82~47.41 ka B.P.东亚夏季风演化历史.BY2δ^18O值在52.2 ka B.P.和49.5 ka B.P.前后显著偏负,指示两次夏季风显著增强阶段,分别对应于格陵兰冰芯记录的DO14和DO13事件.山西白云洞石笋清晰记录了CIS13事件"双峰"结构,与NGRIP冰芯记录相对应,反映了东亚季风边缘区对北大西洋海-气耦合振荡,以及ITCZ南北移动引起的雨带范围变化的敏感响应.但BY2δ^18O记录的CIS13事件转换过程较NGRIP缓慢,其中开始过程呈现"三相位"变化特征:即亚洲夏季风提前出现缓慢增强趋势、在达到水热阈值条件后表现出与格陵兰温度的同步快速爆发、 最后仍持续增强直至峰值;这与热带大西洋和印度洋海盆岩芯反照率记录相似,可能与南大洋越赤道气流以及ITCZ持续北移有关.另一方面,千年尺度事件和百年-年代际振荡幅度分别高达5‰和2‰,明显较东亚季风区其他石笋 δ^18O记录大,尤其是在百年-年代际尺度上呈现出"高频、大幅"的变化特征;表明其敏感响应于不同时间尺度气候波动.功率谱结果表明,其具有明显的50 a、60 a和206 a变化周期,可能受到太阳活动和海洋水文变化的双重影响.
基金supported by the Science Council of Taiwan (NSC 97-2628-M-006-014)the National Natural Science Foundation of China (Grant Nos 40672202 and 40599424)
文摘The causal correlation or linkage between the East Asian Monsoon (EAM) intensity and rise/fall of Chinese dynasties recently proposed by high-resolution paleoclimate reconstructions is examined in detail. Aside from many exceptions to the correlation, both instrumental and historical climate records show strong spatial variations of rainfall on annual-to-decadal scales over eastern China. The relationship between rainfall and EAM intensity also exhibits regional disparity. These observations suggest: (1) Tak-ing paleo-proxy records from a single locality in eastern China to imply changes in drought/wetness as to affect the cultural and political history of China is fraught with uncertainty. (2) On annual-to-decadal scales, the thesis that δ18O in speleothems can be used as a proxy for the EAM strength lacks empirical underpinnings.
基金supported by the National Natural Science Foundation of China (Grant Nos.42172208,41772184&41731174)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB26020000)。
文摘Occurrence or absence of centennial-scale climatic variability during Marine Isotope Stage(MIS)7e,the first peak interval of the Penultimate Interglacial,remains ambiguous due to the limited available high-resolved records.Here,we present a decadal-resolved stalagmiteδ^(18)O record from northern China spanning from 242.3 to 236.8 ka BP,covering MIS7e.The composite KLSδ^(18)O record,integrating this study with the previous record in the same cave,shows a descending trend from TerminationⅢto MIS7e,which follows the increasing Northern Hemisphere summer insolation(NHSI).This observation further emphasizes the important influence of NHSI on the glacial/interglacial transition.There are more large-amplitude,millennial-to centennial-scale variability occurring during TerminationⅢcompared with MIS7e,implying that ice-sheet decay potentially plays an important role in climatic excursions.Four centennial-scale summer monsoon collapses,peaking at~242.1,~240.8,~239.3 and~238.2 ka BP,are detected in our new record,indicating the pervasiveness of the intra-interglacial climatic instability.Given the lack of solar activity and freshwater outbursts data during MIS7e,it is not possible to conclude about the drivers of the identified abrupt climatic anomalous.Following the dynamic mechanisms of sub-millennial climatic anomalous during early Holocene,we tentatively propose that slowdown of the meridional overturning circulation caused by freshwater fluxes into North Atlantic and/or attenuated solar irradiance is the potential forcing for the abrupt climate events within MIS7e.Additionally,attenuated solar irradiance could also result in climatic anomalies through low-latitude processes.
文摘近些年,对于东亚季风区石笋δ^(18)O的气候环境指示意义的争论较多,主要在东亚季风区石笋δ^(18)O代表夏季和风强度、夏季风降水还是水汽源变化。基于中国东部华北地区降水与长江中下游地区降水反相变化和长江中下游地区降水与菲律宾海降水反相变化(遥相关),从年际-年代际到千年-轨道尺度对石笋δ^(18)O与夏季风降水、厄尔尼诺-南方涛动(ENSO)的相互关系进行了探讨分析。通过对比石笋δ^(18)O记录与华北和梅雨区降水,发现石笋δ^(18)O偏负对应华北降水增加,梅雨区降水减少;石笋δ^(18)O偏正对应华北降水减少,梅雨区降水增加。这种对应关系不仅存在年际-年代际尺度,而且在千年-轨道尺度同样存在,石笋δ^(18)O不仅反映夏季风强弱变化,同时与中国东部区域降水关系是明确对应的。通过降水的空间相互关系,发现ENSO活动主要通过影响中国东部降水的空间分布格局而作用于石笋δ^(18)O。La Ni a态导致南海及菲律宾海对流加强,西太副高位置偏北,长江中下游地区梅雨期缩短,华北夏季降水增加,东亚季风区石笋δ^(18)O偏负。El Ni o态,南海和菲律宾海对流受到抑制,西太副高位置南移,长江中下游地区梅雨期延长,华北夏季降水减少,东亚季风区石笋δ^(18)O偏正。另外,水汽源分析发现,菲律宾海水汽输送对东亚季风区降水及降水δ^(18)O贡献相对较小。因此,综合分析认为,东亚季风区石笋δ^(18)O主要反映了亚洲夏季风的强弱变化。
