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1.
在国际古气候模拟比较设计设定的边界条件下（其中包括：海洋表面温度，陆地冰盖，CO2浓度，地球轨道参数等变化）。本文汇报了利用中国科学院大气物理研究所的9层全球大气环流格点模式对末次盛冰期气候进行数值模拟的研究成果。结果表明：末次盛冰期全球年平均温度在低5．3℃，降雨量下降9％，其中大陆年平均降水量仅为目前的71％。通过与其他模式模拟结果和重建古气候资料的对比表明，该模式捕捉到了末次盛冰期干，冷的冰期气候特征。在此基础上，我们根据刘东生等的科研成果，初步探讨了青藏高原在末次盛冰期倘若存在一定范围的冰盖，那么该冰盖会对东亚区域古气候模拟结果产生怎样的冲击。 相似文献
2.
中国内蒙古哈马尔太碱湖Ha01孔岩心13000a以来的古气候记录 总被引：1，自引：0，他引：1
通过对内蒙古哈马尔太碱湖Ｈａ０１孔岩心古气候记录的研究，划分出１３０００ａ以来的１０个气候期及若干气候阶。对比表明，与全球气候变化是一致。在末次冰期盛冰期之后，冰后期之前，有三次明显的急速降温，先后有老仙女木冰阶、中仙女木冰阶和新仙女木冰队；冰后期以来，有两次大幅度的降温事件，均具有全球性，一次冷点是７６４０ａＢ．Ｐ．，一次冷点为５０００ａ．Ｂ．Ｐ．，前者相当Ｄｅｎｔｏｎ称作的第一新冰期，后者相当 相似文献
3.
通过对内蒙古哈马尔大碱湖Ｈａ０１孔岩心古气候记录的研究，划分出１３０００ａ以来的１０个气候期及若干气候阶。对比表明，与全球气候变化是一致的。在末次冰期盛冰期之后，冰后期之前，有三次明显的急速降温，先后有老仙女木冰阶、中仙女木冰阶和新仙女木冰阶；冰后期以来，有两次大幅度的降温事件，均具有全球性，一次冷点是７６４０ａＢ．Ｐ，一次冷点为５０００ａＢ．Ｐ，前者相当Ｄｅｍｏｎ称作的第一新冰期，后者相当第一新冰期。近２０００年该盐湖的气候变化与中国历史文献资料相吻合。 相似文献
4.
在国际古气候模拟比较计划设置的标准试验方案下,首先利用中国科学院大气物理研究所的全球大气环流模式（IAP-AGCM）模拟了末次盛冰期东亚气候状况,然后通过4组数值敏感性试验逐一模拟了大气CO2浓度、海洋表面温度（SST）和海冰、陆地冰盖和地形、东亚植被变化4项强迫因子的单独气候效应,进而对末次盛冰期东亚气候的成因进行了检测。结果表明,末次盛冰期除华南局部略有升温外,中国年均地表气温显著降低,降温幅度总体上向北增大,青藏高原处存在一个降温中心。其中,SST和海冰变化是华南局部略偏暖的主因,它同时导致了东亚其他区域地表气温的显著降低,特别是在东北亚地区;陆地冰盖和地形变化对于东亚地表气温的显著冷却作用主要体现在东亚的西北部;大气CO2浓度降低会引起东亚地区0.2～0.9℃的普遍降温;相对而言,东亚植被的降温作用（0.5～1.0℃）主要显现在中国40°N以南的区域。与此同时,SST和海冰变化能引起中国东部年均降水一定程度的减少,而大气CO2浓度、陆地冰盖和地形、东亚植被单独变化均不会显著影响东亚年均降水的分布状况,然而,上述四项因子的共同变化会通过协同作用引起中国东部年均降水的显著减少,西部地区降水则与现在差别不大。此外,末次盛冰期东亚夏季风的显著减弱源于SST和海冰变化,冬季风变化则可归因于SST和海冰、陆地冰盖和地形的变化。 相似文献
5.
文章回顾了1965年李四光先生追寻末次冰期对环境影响的讲话,以及40余年来在天津-河北沿海钻孔地层中、末次盛冰期下切河谷的发现过程。在源到汇过程中,起码自晚更新世以来,研究区已经是古黄河沉积区,多处发现的末次盛冰期下切河谷底板多位于30~32 m深度,低于全新统底板一般在20 m的深度;与长江口地区钻孔末次盛冰期下切河谷深62 m相比,研究区下切河谷规模不如前者,也没有一个统一的大河口。末次盛冰期下切河谷最远地点,是距现代海岸约80 km的河北省孟村回族自治县县城北侧,即西汉黄河亚三角洲叶瓣顶部。众多钻孔见早全新世快速沉积,只能是黄河支流有这样充足的泥沙供给,在局部顶托了早全新世海侵作用发生。 相似文献
6.
华北平原石家庄东南部宁晋泊地区湖相地层的年龄测定 总被引：1，自引：0，他引：1
对华北平原宁晋泊地区南王庄剖面和钻孔上部岩心的湖相沉积物作了^14C、细颗粒(2～8μm)多矿物组分的热释光(TL)和光释光(OSL)3种技术的年代测定，确定了宁晋泊地区湖相地层的年龄。剖面上部12．90m为距今3万年以来的沉积物，其中最顶部的5.34m为全新统，其下为上更新统，年龄分辨率高，建立了一个可信的沉积地层年代序列，为研究华北平原宁晋泊地区的古气候和古环境演化提供了准确的年代学资料。 相似文献
7.
末次间冰期以来地球气候系统的突变 总被引：14，自引：0，他引：14
地球气候系统的突然变化是近年来地学研究的热点。取自极地冰芯、海洋沉积物和陆地的古气候记录表明,末次间冰期以来全球经历了一系列数百年—千年时间尺度的气候突变事件,证明了在末次冰期—间冰期旋回大尺度气候变化背景下,全球气候存在较大不稳定性这一基本事实。尽管末次间冰期以来这些数百年—千年时间尺度气候突变事件的成因和影响范围还存在明显的不确定性,但已从诸如末次间冰期(MIS 5e)中期的干冷事件、末次冰期的Dansgaard-Oeschger旋回、Heinrich事件和Younger Dryas事件以及发生在全新世冰后期的一些降温事件的研究中,获得对过去130 ka来气候变化过程总体上的认识和理解。综述了近年来的主要研究成果,介绍了有关末次间冰期以来全球气候突变事件发生的时间、过程和机制等最新的研究进展。 相似文献
8.
稻城冰帽区更新世冰川测年研究 总被引：14，自引：6，他引：8
通过ESR和14C测年对典型冰碛物进行直接和间接定年, 并结合冰碛地貌形态和位置, 确定稻城冰帽区自中更新世以来经历了6次较大规模的冰川前进, 依次与MIS-16、 MIS-6、 MIS-3中期、 MIS-2早期、全球意义上的末次盛冰期(MIS-2)和冰后期对应, 冰川作用规模基本上逐渐减小.最早、规模最大的冰川作用发生在570 ka BP前后, 意味着本段高原面在570 ka BP之前已进入了冰冻圈, 且自那时起, 该区经历了较大规模的抬升作用. 全新世到来之前, 稻城冰帽全部消失了, 它是一个随着气候冷暖波动逐渐后退的过程, 不是以死冰的方式突然消亡. 值得注意的是, 末次冰期大间冰阶中期(MIS-3b)的冰川前进规模超过了末次盛冰期(MIS-2), 表明末次冰期最盛期在全球范围内的不同步性. 其不同步的原因可能是: MIS-3中期, 北半球夏季太阳辐射相对较低, 但其海陆分布状况能够诱发较强的南亚夏季风, 它给以季风降水为主要补给的海洋性冰川区带来较多的降水, 结合该时段较低的温度, 有利于冰川较大规模前进; 末次盛冰期时, 气候严寒, 但夏季风微弱, 降水稀少, 冰川平衡线下降程度反而不及MIS-3b. 相似文献
9.
显生宙全球气候变化与生物绝灭事件的联系 总被引：3，自引：1，他引：3
根据显生宙各地质时期全球气候敏感沉积物和生物地理单元数据库，显生宙（寒武纪至中新世）可识别出２４次全球范围内不同级别的气候变化事件。有些事件与全球生物事件有着密切的联系，而不少则并无重要联系，即使这两种事件发生的时间和规模上存在着明显的一致性，也并不一定就存在着因果关系。这２４次事件根据二者的一致性和不一致性，可归纳为两类：（１）早寒武世末（一致）；（２）晚寒武世末（不一致）；（３）早奥陶世末（Ｉｂｅｘｉａｎ末，不一致）；（４）奥陶纪末（一致）；（５）志留纪兰多维列世（不一致）；（６）志留纪文洛克世早期（不一致）；（７）志留纪文洛克世末（不一致）；（８）志留纪罗德洛世末（不一致）；（９）志留纪普利道里世末（不一致）；（１０）早泥盆世埃姆斯期初（不一致）；（１１）中泥盆世艾菲尔期末（一致）；（１２）中泥盆世吉维特期末（一致）；（１３）晚泥盆世弗拉斯期末（一致）；（１４）泥盆纪末（不一致）；（１５）早石炭世末（一致）；（１６）晚石炭世维斯发期末（一致）；（１７）早二叠世萨克马尔晚期（一致）；（１８）二叠纪末（一致）；（１９）早三叠世（一致）；（２０）中—晚三叠世（不一致）；（２１）早侏罗世赫塘期（不一致）；（２? 相似文献
10.
末次盛冰期以来中国北方干旱区演化及短尺度干旱事件 总被引：13，自引：0，他引：13
对中国北方干旱区329个古土壤和湖泊沉积物的14C年龄数据的时空分布及频数统计分析表明, 从末次盛冰期至冰消期, 我国整个干旱区受控于西风带;在全新世, 干旱区东部环境变化主要受控于东亚季风系统, 而其西部仍属西风控制区。全新世以来, 中国干旱区存在至少4次百年至千年级的干旱事件, 且干湿变化基本上与全球西风模式区的气候变化相反, 而与低纬非洲干旱区气候变化有很好的对应关系 。由于我国干旱区和非洲干旱区的干湿变化均受控于来自低纬热带海洋的夏季风的强弱, 因此 两区干旱事件的同时发生可能与低纬热带海洋的气候变化有关。同时, 本文利用14C年龄的时空分布和其它地质资料, 初步恢复了末次盛冰期和全新世最适宜期我国干旱区的沙漠分布状况。 相似文献
11.
Mollusk record of millennial climate variability in the Loess Plateau during the Last Glacial Maximum 总被引：2，自引：0，他引：2
NAIQIN WU TUNGSHENG LIU XIUPING LIU ZHAOYAN GU 《Boreas: An International Journal of Quaternary Research》2002,31(1):20-27
A high-resolution terrestrial mollusk record from the Loess Plateau of China has been studied to characterize climate variability during the Last Glacial Maximum (LGM). The rapid successions in mollusk taxa in the Weinan loess sequence reveal that climate changes occurred at least four times in this period. In the loess region, millennia-scale climate fluctuations existed, as documented in the grain size and weathering intensity records. Our results show such millennia-scale fluctuations reflecting changes in both temperature and precipitation, rather than a simple cold and warm alternation. Changes in temperature and precipitation were not in phase during the LGM. Temperature varied earlier than precipitation, which could have been the effect of winter and summer monsoon interactions. Our data also reveal that the East Asian summer monsoons could reach the southeast part of the Loess Plateau during the whole of the LGM. The intensification of winter monsoons during the LGM led to short duration of summer monsoons annually impacting on the Loess Plateau, but the intrinsic intensity of summer monsoons would not have changed significantly, thus providing the thermo-hydrological conditions for temperate-humidiphilous mollusks to persistently grow and develop in the glacial age. 相似文献
12.
本文通过对渭南黄土剖面末次盛冰期地层较高分辨率的蜗牛化石记录研究，发现这一时期特征蜗牛种类峰值的演替反映了古气候的演化过程和温，湿度的组合关系。气候变化显示出百年-千年尺度波动的特征，温度的变化明显地要早于湿度（降水）的变化1000-2000a，表现为变冷-冷湿-冷干-温干-温湿的气候过程，研究认为造成这一气候特点的原因是东亚冬，夏季风共同作用的结果，可喜温湿蜗牛种类的研究，揭示出东亚夏季风在这一时期至少能够持续地影响到黄土高原的东南部地区，这个时期冬季风强化的结果之一是影响了夏季风在这一地区滞留的时间，加大了季节性的差异，分析表明尽管夏季风在这一地区滞留的时间缩短，但维持了它固有的强度，提供了适量的水热条件供喜温湿蜗牛种类在这一寒冷阶段持续地生长和发育。 相似文献
13.
The effect of seasonally reversing monsoons in the northern Indian Ocean is to impart significant changes in surface salinity (SS). Here, we report SS changes during the last 32 kyr in the Lakshadweep Sea (southeastern Arabian Sea) estimated from paired measurements of d18O and sea surface temperature (SST) using Globigerinoides sacculifer, an upper mixed layer dwelling foraminifera. The heaviest d18OG.sacculifer (–0.07±0.08‰) is recorded between 23 and 15 ka, which could be defined as the last glacial maximum (LGM). The d18OG.sacculifer shift between the LGM and Holocene is 2.07‰. The SST shows an overall warming of 2°C from the LGM to Holocene (28°C to 30°C). However, coldest SSTs are observed prior to LGM, i.e., ~27 ka. The SS was higher (~38 psu) throughout most of the recorded last glacial period (32.5–15 ka). This high salinity together with generally lower SSTs suggests a period of sustained weaker summer or stronger winter monsoons. The deglacial warming is associated with rapid reorganization of monsoons and is reflected in decreased salinity to a modern level of ~ 36.5 psu, within a period of ~5 kyr. This indicates intensification of summer monsoons during cold to warm climate transition. 相似文献
14.
Huei-Fen Chen Yuan-Pin Chang Shuh-Ji Kao Min-Te Chen Sheng-Rong Song Li-Wei Kuo Shie-Ying Wen Tien-Nan Yang Teh-Quei Lee 《Journal of Asian Earth Sciences》2011,40(6):153-1249
We present a mineralogical and geochemical study of core MD012404, retrieved from the central Okinawa Trough (OT) of the East China Sea. Our studies reveal that the sediment sources of the core have been changed through time during the past 100 ka. Our mineralogical proxies indicate that the sediments source from the Yangtze River correlates well sea-level changes before 24 ka. Our Ti/Al ratios otherwise indicate an increase of sediment supply from eastern Taiwan after 26 ka. The cooler climate of the Last Glacial Maximum (LGM, 23～19 ka) led to a reduction in fluvial sediments from the Yangtze River. However, subsequent climate warming (after ～19 ka) resulted in an abrupt increase in fluvial sediments. After the LGM, the Kuroshio intrusion flow into the OT may have increased. We also infer anomalous changes in eolian sources transported by winter monsoons during the LGM and at 80 ka based on an eolian mineralogical indicator (feldspar). We conclude that the sediment source of core MD012404 is primarily of terrestrial origins, but influenced by sea-level changes and variations in the East Asian monsoon. 相似文献
15.
Climate fluctuation on a kiloyear scale during the Late Last Glacial in Mu Us Desert,China: evidence from Rb and Sr contents and ratios 总被引：1，自引：0，他引：1
Yuejun Si Baosheng Li David Dian Zhang Xiaohao Wen Fengnian Wang Shuhuan Du Dongfeng Niu Yihua Guo 《Environmental Earth Sciences》2014,72(11):4521-4530
The MGS2 segment of the Milanggouwan stratigraphical section in China’s Salawusu River Valley records 5.5 sedimentary cycles consisting of dune sands alternating with fluviolacustrine facies or/and palaeosols. The high Rb and Sr contents and low Rb/Sr ratios in the fluviolacustrine facies indicate the presence of a warm and humid climate, and vice versa for a dry and cold climate. Rb and Sr appeared to have 5.5 element cycles that are consistent with the sedimentation changes, and each cycle lasts about 2 ka on average. This study suggests that the observed cycles mainly resulted from variations in the strength of the East Asian winter and summer monsoons, and the MGS2 segment experienced six cold-dry winter monsoons and five warm-humid summer monsoons during the OIS2. In addition, the millennial-scale monsoonal climate fluctuations revealed by the element cycles corresponded well with the Dansgaard–Oeschger cycles recorded in the Greenland ice cores and Heinrich events in the North Atlantic marine sediments. Therefore, the monsoonal climate fluctuations revealed by the Rb and Sr in the MGS2 segment were likely triggered by global climate change. 相似文献
16.
《Quaternary Science Reviews》2007,26(19-21):2505-2525
New Zealand's climate during the Last Glacial Maximum (LGM) has been investigated using the United Kingdom Met Office global (HadAM3H) and regional model (HadRM3H). All models were set up according to the glacial conditions as specified by the Paleoclimate Modelling Intercomparison Project (PMIP), although SSTs and sea-ice were supplied from a set of prior coupled model (HadCM3) runs. The simulated climate of New Zealand during the LGM was mainly compared against a control simulation which was set up for pre-industrial conditions. New Zealand's simulated LGM climate was cooler than today, varying spatially between 2.5 and 4 °C. There was an increase in seasonality in temperature with the seasonal cooling being largest during winter. Excluding the Alpine/Fiordland region, the largest cooling geographically took place in the east of the South Island (ESI). Annual mean precipitation was reduced but there were significant regional and seasonal variations. The main band of precipitation along the West Coast shifted westwards, resulting in a reduction in precipitation over those regions in the Southern Alps that receive the largest amount of precipitation in today's climate. The westerly circulation increased considerably over the North Island and the northern part of the South Island, but did not change much over the rest of the South Island. The stronger westerly wind accentuated the cooling over the western and northern parts of the North Island and it probably reduced the occurrence of incursions of tropical lows over the north of the North Island. The westerly winds were weaker over New Zealand during winter, which appears to be related to enhanced blocking activity during that season. The number and the strength of the southerlies increased, and they were capable of bringing very cold polar air over most of the country. The east of the South Island was affected especially by these cold winds.The simulated cooling during the LGM is not sufficient to limit forest growth. It is proposed here, that together with the general drier and colder conditions, it was the increase in seasonality and extremes of climate that limited the growth of certain vegetation types. 相似文献
17.
研究过去气候快速变化能为当前极端气候分析和未来环境预测提供自然背景理解。亚洲季风在北半球乃至全球的第四纪气候变化中扮演着重要角色,其演化是全球气候变化背景下的典型区域响应。然而,不同地质载体及不同指标所记录的亚洲冬、夏季风变化存在着较大差异,产生差异的原因及受到的动力机制是值得深入研究的科学问题。渭河盆地位于黄土高原和古三门湖沉积交叠的区域,是研究第四纪亚洲季风演化的理想场所。在盆地西南部西安市户县和长安县获取了两个黄土沉积钻孔,户县ZZC孔长4 m,长安县XFC孔长3 m,两孔的年代均超过25 ka。通过两钻孔的粒度和元素地球化学等代用指标研究,对比分析不同指标对气候变化的敏感度差异,反演了末次冰盛期(LGM)以来的区域沉积环境变化,并尝试探讨该时期发生的气候突变事件及反映的季风强度变化。结果表明,两钻孔的平均粒径从LGM到中全新世逐渐变细,中全新世之后少许变粗,空间上表现出一致性,总体反映了末次冰盛期以来的冬季风强度演化;Ca/Ti反映了与季风降水相关的淋溶强度,从LGM到全新世暖期夏季风逐渐减弱,并记录了若干次气候快速变化。粒度和元素比值变化表明,渭河盆地沉积良好地记录了末次冰盛期至全新世的大幅冷干-暖湿波动及若干次持续时间较短的快速水文变化事件,主要是受到太阳辐射和冰量等因素调控的影响。由于渭河盆地有上千米的新生代沉积,未来开展高分辨率研究有望揭示不同时间尺度季风变化特征及其与区域和全球变化的联系。 相似文献
18.
青藏高原与东西两侧大陆的气温差异 总被引：1，自引：1，他引：0
主要对我国昆仑山-秦岭以南的东西部气温的差异问题进行简要讨论。比较气象台站实测气温和换算至海面后的温度,明显反映西部、中部和东部3个地貌阶块的海面气温自西向东逐级降低。我国西部高原地区全年温度较东部丘陵平原区相对偏高,主要原因在于青藏高原和南亚次大陆主要为西南季风所控制,致使气温相对偏高,而东部深受东南季风和来自高纬冬季风的影响,气温相对偏低。因而,全球变化和区域性季风气候是导致东西部气温差异的主导原因,而不能笼统地归之为高原增温效应和东部"冷槽"影响所致。 相似文献
19.
青藏高原东北部共和盆地风成沉积地球化学特征及其揭示的气候变化 总被引：4，自引：0，他引：4
通过对共和盆地东部风成沉积的地球化学分析,并结合14C和OSL年代,重建了区域末次盛冰期以来气候变化过程。21 ka BP之前气候寒冷偏湿,21～15.82 ka BP为末次盛冰期(LastGlacial Maximum,LGM),气候极为寒冷干燥;15.82～9.5 ka BP气候转暖且偏干,其中14.5～13.6ka BP和11.9～9.5 ka BP气候明显冷干,分别为老仙女木时期(Oldest Dryas,OD)和新仙女木时期(Younger Dryas,YD),而15.82～14.5 ka BP和13.6～11.9 ka BP(BФlling-AllerФd暖期,B/A)相对温暖;9.5～7.2 ka BP暖湿程度明显提高,7.2～5.1 ka BP气候波动频繁,相对冷干和相对暖湿多次更替。5.1～2.7 ka BP暖湿程度基本稳定,之后气候趋于寒冷但湿度明显较大。这些气候变化过程与青藏高原大量的古气候信息记录具有良好的一致性,表明共和盆地气候变化与青藏高原气候变化的高度一致性。 相似文献
20.
The evolution and future projection of the regional and global monsoons, one of the major components of Earth climate system in the low-latitudes and middle-latitudes, has long been the research focus in the paleoclimate and modern climate communities. Session 4 of the 4th Conference on Earth System Sciences (CESS) in Shanghai focused on the evolution, variability, and driving mechanism of regional and global monsoon system across multiple timescale, and the role of the monsoon system in changes in the Earth system. During the session, the issues of features of past and contemporary monsoons based on observation data and geological reconstruction, model simulation of past and contemporary monsoons, and response of monsoon climate to the past and present global warming were intensively discussed. The future research directions were also addressed. 相似文献