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1.
中纬度亚洲地区存在主要受季风环流影响的东南部湿润地区(简称季风区)和主要受西风环流控制的内陆干旱区(包括青藏高原北部高寒干旱区,简称西风区)。根据对近年来新发表的气候变化记录证据梳理总结,发现西风区在中—晚全新世气候湿润,与亚洲季风在早—中全新世强盛的格局显著不同。过去千年的西风区中世纪暖期干旱,而小冰期相对湿润,与此相对,万象洞石笋氧同位素记录则显示季风降水在中世纪暖期时整体处于高值,在小冰期处于低值段。在近百年,尤其是近50a,西北干旱区湿度增加,而季风影响范围内的西北东部和华北等地变得更干。不仅如此,在分属西风和季风影响区的青藏高原北部和南部,年代际—百年尺度上降水变化也表现出反相位关系。据此我们提出,亚洲中部西风带控制区在现代间冰期从数千年到年代际的各个时间尺度上均存在不同于季风区的湿度(降水)变化模式,称之为现代间冰期气候变化的西风模式。 相似文献
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北大西洋涛动对青藏高原夏季降水的影响 总被引：4，自引：2，他引：2
利用青藏高原中东部1961-2004年60个气象台站夏季(6-8月)降水资料,通过旋转经验正交函数分解发现青藏高原夏季降水存在南北反向变化的空间模态,分析表明这种变化模态与北大西洋涛动(NAO)密切相关.利用NCEP/NCAR再分析资料进行环流场分析,探讨了NAO对青藏高原这种降水空间变化模态的影响机制.结果表明:强NAO年份时,高原北部水汽输送通量强度增强,水汽辐合增强,而高原南部水汽输送通量强度减弱,此时高原切变线位置明显偏北,正是在这种水汽输送和环流形式配置下使得高原北部降水偏多而高原南部降水偏少;在弱NAO年份,上述情况基本相反. 相似文献
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青藏高原气候系统变化及其对东亚区域的影响与机制研究进展 总被引：1，自引：0，他引：1
青藏高原地区特殊的大气圈、水圈、冰冻圈、生物圈等多圈层相互作用过程及其变化,不仅对青藏高原及其周边地区的气候格局和变化有重要影响,而且对东亚、北半球乃至全球的环流形势和异常产生深远影响。为此,全球变化研究重大科学研究计划于2010年9月启动了"青藏高原气候系统变化及其对东亚区域的影响与机制研究"项目,旨在开展青藏高原环境、地表过程、生态系统对全球变化的响应及其对周边地区人类生存环境影响的综合交叉研究,以揭示青藏高原气候系统变化及其对东亚区域的影响机制,提出前瞻性的应对气候变化与异常的策略,减少其导致的区域自然灾害的损失。项目实施近3年来,开展了青藏高原首次"星—机—地"综合立体协同观测试验和大规模地气相互作用综合观测试验。在遥感结合地面观测估算青藏高原地表特征参数和能量通量方法,高原地区上对流层和下平流层结构,高原季风与东亚季风和南亚季风之间的内在联系,中国及青藏高原地区太阳辐射和风速的年代际变化趋势,青藏高原春季感热源减弱及其对亚洲夏季风和中国东部降水的影响,以及极高海拔地区土地覆被格局等方面取得了一些突出进展。 相似文献
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中国东部季风区和西北干旱区分别受控于季风和西风环流,是全球变化响应的敏感区域.过去50年全球升温,西北干
旱区降水显著增加,而东部季风区的降水变化不明显.在未来全球继续变暖的情况下,两个地区降水将如何变化尚不清楚.利
用湖北神农架三宝洞和新疆特克斯科桑洞的石笋生长速率记录,考察它们对降水变化的响应,研究冰期-间冰期旋回中两地
的降水变化及其差异,为未来气候变暖下的中国降水模型预测提供一个验证实例.研究表明,500ka以来中国东部季风区和西
部干旱区降水呈现冰期-间冰期波动变化,气温偏高的间冰期降水量大.但是,中国西北干旱区降水的响应滞后于东部季风
区,指示两地降水对温度变化的响应可能并非完全同步. 相似文献
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回顾了课题组近年来有关末次冰盛期和中全新世气候模拟分析的研究进展,包括中国气候、东亚和全球季风以及相关的主要大气环流系统等变化。多模式试验数据的分析表明,末次冰盛期中国降温和年均有效降水变化与重建记录定性一致,但模拟幅度偏弱;中国冻土区扩张、永冻土区活动层变薄,中国西部冰川物质平衡线高度降低;东亚季风变化在不同模式间差异较大,中国季风区范围和季风降水减小,北半球陆地季风区南移、全球季风区缩小和降水强度减弱共同引起全球季风降水减少;全球降水和潜在蒸散发共同减小使得全球干湿变化总体很小;北半球西风带在高层北移、低层南移,热带宽度变化依赖于指标的选取,厄尔尼诺—南方涛动气候影响、热带太平洋沃克环流均减弱并东移。在中全新世,多模式模拟的中国年和冬季偏冷仍然与大部分重建记录显示的偏暖不同;东亚冬季风增强,东亚夏季降水变化存在空间不一致性;中国和全球尺度的季风区范围和季风降水均增加;东北多年冻土退化、青藏高原多年冻土向低海拔扩张,北半球永冻土区减小、季节性冻土扩张、冻土区北退、永冻土区活动层变厚;全球干旱区面积总体变化很小;夏季东亚西风急流显著减弱并北移,厄尔尼诺—南方涛动减弱,热带太平洋沃克环流... 相似文献
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159个湖泊地质记录提供了欧亚大陆两万年来大气环流变化信息。盛冰期北欧低湖面而地中海地区高湖面,反映冰流反气旋控制和西风带南迁。随着晚冰期冰流高压减弱、西风带回迁,南欧为低湖面而北欧低湖面范围减小。全新世早中期北欧阻塞高压发展,干燥炎热;南欧地区性季风环流加强,气旋雨增加。中国青藏高原至东西伯利亚高湖面,反映东亚季风扩张、季风雨以及高原对流雨增加。晚更新世以来湖泊所反映的西风带和季风环流变化,揭示了辐射异常和北半球冰流消长的动力控制。 相似文献
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选取青藏高原36条(34个地点)由孢粉已重建的降水序列(8条)和化石孢粉谱(28条),分别采用直接提取和现代类比法获得1852个具有年代的定量降水数据,以高原4个分区为单位,建立青藏高原晚冰期以来古降水数据集。构建分区古降水空间模拟-多区面积加权的集成方法,即借助GIS分析,基于现代高原降水空间分布的地理因子模拟,集成重建晚冰期以来高原古降水序列。结果表明:16~12 ka B.P.,高原总体降水量较少,其中16 ka B.P.不到200 mm,约为现代降水量的一半,15~13 ka B.P.后降水显著增长,较前期上升70 mm;13~12 ka B.P.,又跌至220 mm,较现代低100 mm。进入全新世后,降水量迅速增长,降水在全新世早期的9.2~8.7 ka B.P.即达到最大值,高出现代70 mm,9.2~5.0 ka B.P.为全新世湿润期,平均高出现代50 mm;5 ka B.P.之后,降水波动较小,与现代基本持平。集成降水与其他高低分辨率环境记录有很好的可比性,说明集成序列有很好的代表性和一定的准确性。此外,高原降水变化区域差异明显,全新世最大降水呈现出西早东晚,西南季风(ISM)区早于东南季风(EASM)区的特点,高原西部和南部全新世早期9 ka B.P.左右即达极大值,而高原东缘迟至全新世中期的8.0~7.5 ka B.P.;降水增加最为明显的是高原西北部,最盛期降水约高出为现代的1倍,高原东部和南部现季风控制区域,只比现代高出0.2倍。 相似文献
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青藏高原南北降水变化差异研究 总被引：13，自引：5，他引：8
利用青藏高原1960-2004年近45 a气象台站年降水记录, 对高原中东部年降水做了空间变化分析, 发现高原以唐古拉山为界, 高原南北降水变化存在明显差异, 特别是高原南部和东北部降水几乎成相反的变化. 进一步分析5个重建的长时间降水序列, 发现青藏高原南北降水在百年时间尺度上也存在明显的差异. 在百年时间尺度上, 过去600 a高原南北降水变化都在1740年和1850年左右发生突变. 1740年以前, 整个高原北部降水都在波动中增加, 而高原南部在减小;1740-1850年期间, 高原北部降水在波动中减小, 而高原南部在增加;1850年以后, 高原北部降水又在波动中增加, 而高原南部降水在减小. 高原南北降水变化的空间差异主要是由季风和西风带决定的. 相似文献
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水体稳定同位素作为贯穿水循环的介质,是研究大气环流过程和传输路径的有效手段。介绍了水体稳定同位素技术在青藏高原大气环流研究中的应用,聚焦典型站点降水、河水和冰芯等水体稳定同位素的季节和空间变化特征,揭示了大气环流对地表水稳定同位素高程效应的显著影响,以及大气降水对地表水的主导;引入降水稳定同位素标准判断亚洲夏季风爆发时间;通过冰芯稳定同位素揭示了厄尔尼诺—南方涛动对整个青藏高原水循环的影响及其响应机制的区域差异。在未来的研究中,将加强跟地球系统模型的结合,关注水体稳定同位素在不同时间尺度的控制因子、突变过程以及激发机制,进而量化古气候替代指标中的稳定同位素变化、从较长的时间尺度上重建影响青藏高原的水汽来源的演变历史。同时关注过量氘等具有水汽来源诊断能力的参数,研究其与大尺度环流参数的相关性,从海表温度、蒸发等陆—气相互作用分析并将高原环流过程与全球环流过程紧密结合综合分析。 相似文献
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Guboglo M. N. 《GeoJournal》1980,4(1):53-58
International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen. 相似文献
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Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth
B. P. Kondratyev 《Astronomy Reports》2017,61(8):709-714
It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T 3 = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″. 相似文献
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Chronological analyses of correlations between certain global repeating events (mass extinctions of marine organisms, meteorite impacts, and flashes in the frequency of geomagnetic reversals) during the Phanerozoic Eon and the motion of the solar system in the Galaxy are presented for five rotationally symmetrical models for the regular Galactic gravitational field. Thirteen of sixteen mass-extinction events can be described by a repetition interval of 183±3 million years. This is in agreement with the anomalistic period (interval between two subsequent passages of the Sun through the apocenter of its Galactic orbit) in the model of Allen and Martos. The positions of the minima and maxima in Gaussian functions approximating the frequency distribution for geomagnetic reversals also agree with the times of passage of the Sun through the apocenter and pericenter, respectively, of its Galactic orbit in this model. The maximum in the distribution of the deviations of the dates of mass extinctions from the nearest dates of impacts of large, crater-forming bodies is close to zero, providing evidence that many such events are correlated. As a rule, extinctions follow impact events. The impacts of large bodies have occurred most often when the solar system passes through the Galactic plane, while mass extinctions occur more often at some distance from the Galactic plane (about 40 pc). As a rule, intervals of increases in the frequency of geomagnetic reversals coincide with dates of impacts of large bodies. At the same time, these intervals do not show a clear correlation with the dates of mass extinctions. The intensity of mass extinctions, like the energy released by impacts, is consistently higher in periods when the Sun is moving from the apocenter toward the pericenter of its orbit, than when it is moving from the pericenter toward the apocenter. Thus, there is evidence for a variety of relationships between repeating global events in the Phanerozoic and the motion of the Sun in the Galaxy. Long-period variations in the frequency of geomagnetic reversals are correlated with the orbital motion of the Sun, and increases in the frequency of geomagnetic reversals are correlated with impacts. Mass extinctions are correlated with the impacts of large bodies, whose motions may have been perturbed by clouds of interstellar material concentrated toward the Galactic plane and by the shock front associated with the Perseus spiral arm, through which the solar system passes. The velocity of the Sun relative to the spiral pattern is estimated. 相似文献
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摩擦桩基桩土间极限摩阻力取值问题探讨 总被引：1，自引：0，他引：1
通过对广珠东线高速公路横沥大桥的试桩及土体的工程地质条件分析,总结出影响摩擦桩基桩土间极限摩阻力取值的一般问题以及解决问题的方法和措施。 相似文献
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位于华北和扬子两板块碰撞带中的苏鲁榴辉岩形成的温压条件不但是超高压，而且是高温。榴辉岩的PTt轨迹表明其为陆-陆磁撞俯冲带的产物。榴辉岩的区域性围岩花岗质片麻岩为新元古代同碰撞期花岗岩，榴辉岩及其他直接围岩皆呈包体存在于其中，并见新元古代花岗岩呈脉状侵入榴辉岩包体中。区域性围岩新元古代花岗岩的锆石中发现有柯石英、绿辉石等包裹体，表明新元古代花岗岩的组成物质也经受过超高压变质作用，且榴辉岩与围岩新元古代花岗岩的锆石U-Pb体系同位素年龄基本相同。但新元古代花岗岩所记录的变质作用和变形作用期次（或阶段）却少于榴辉岩。椐上述可得如下推断：超高压榴辉岩与新元古代花岗岩岩浆是同时在碰撞带底部（俯冲板块前部）形成的；榴辉岩的第一折返阶段是由新元古代花岗岩岩浆携带上升的，其第二折返阶段是和新元古代花岗岩一起由逆冲及区域性隆起而上升，遭受剥蚀。 相似文献
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某高速公路下伏煤矿采空区稳定性分析 总被引：10，自引：0，他引：10
在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。 相似文献
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The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads 总被引：3，自引：1，他引：2
Clemente Irigaray Francisco Lamas Rachid El Hamdouni Tomás Fernández José Chacón 《Natural Hazards》2000,21(1):65-81
In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning. 相似文献
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The structure of the eastern Pyrenees consists mainly of south-directed thrusts involving basement and cover rocks. An antiformal stack developed by the piling up of basement thrust sheets which outcrop in the Axial zone. These structures account for a thin-skinned thrust model rather than a vertical fault model in which the Axial zone would be essentially autochthonous, and the North-Pyrenean fault the axial plane of a fan thrust system. New data from the Eastern Pyrenees and the thin-skinned model suggest that(1) the structure east of the Pedraforca nappe is similar to that of the Central Pyrenees; (2) the cover rocks of the South-Pyrenean units and of the Axial zone-after restoration—built up a northwards-thickening prism consistent with the existence of a unique Pyrenean sedimentary basin during Mesozoic time; (3) the Axial zone is only a complex antiformal stack developed as a part of South-Pyrenean system related to the Paleogene thrusting-tectonics. The Axial zone palaeogeographic area had no special meaning during Mesozoic time. 相似文献