Secular Dynamics of Asteroids in the Inner Solar System     

Patrick Michel  Christiane Froeschlé  Paolo Farinella 《Celestial Mechanics and Dynamical Astronomy》1997,69(1-2):133-147

In the last three years we have carried out numerical and semi-analytical studies on the secular dynamical mechanisms in the region (semimajor axis a < 2 AU) where the NEA orbits evolve. Our numerical integrations (over a time span of a few Myr) have shown that: (i) the linear secular resonances with both the inner and the outer planets may play an important role in the dynamical evolution of NEAs; (ii) the apsidal secular resonance with Mars could provide an important dynamical transport mechanism by which asteroids in the Mars-crossing region eventually achieve Earth-crossing orbits; (iii) in this region, due to the interaction with the terrestrial planets, the Kozai resonance can occur at small inclinations, with the argument of perihelion ω librating around 0° or 180°, providing a temporary protection mechanism against close approaches to the planets. The location of the linear secular resonances in this zone has also been obtained by an automatic procedure using a semi-numerical method valid for all values of the inclinations and eccentricities of the small bodies, and also in the case of libration of the argument of perihelion. A map of the secular resonances in the (a, i) plane shows — in agreement with the numerical integrations — that all the resonances with the terrestrial and giant planets are present, and also that some of them overlap. Thus the way is now open to fully take into account secular resonances in modelling the dynamical evolution of NEAs. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

2015年广东开汛前后旱涝急转特征及成因分析     

于玲玲  麦健华  纪忠萍  张东 《热带气象学报》2021,(44):611-622

利用1961—2015年广东86站3—5月逐日降水资料、NCEP/NCAR再分析资料及NOAA的Hysplit后向轨迹模式资料和海温资料,分析了2015年广东开汛前后旱涝异常特征,旱涝急转前后的大气环流和水汽条件转变及成因。(1) 2015年5月第1候广东发生了严重的旱涝急转事件,旱涝急转前全省严重干旱,旱涝急转后广东大部地区降水异常偏多。(2) 旱涝急转前后,500 hPa中高纬度由“两槽两脊”转为“两脊一槽”和“两槽一脊”,副高持续加强,广东地区高层辐散和低层辐合加强,地面由冷空气控制广东转为冷暖空气在广东交汇;水汽输送通道由北部湾和长江中下游地区转为南海南部和中南半岛南部海面,广东低层水汽净流入增加。 (3) 黑潮区、北太平洋中部、Ni?o3、Ni?o4区及印度洋和南海的海温异常增暖造成了旱涝急转前后大气环流和水汽的转变。  相似文献   

国际气候治理中的公正转型议题：概念辨析与治理进展     

张莹  姬潇然  王谋 《气候变化研究进展》2021,17(2):245-254

国际气候治理中的公正转型议题涉及就业、关乎民生,是各国都很关注的政策领域之一,因此也被视为是支持应对气候变化的一种重要社会机制。近年来,国际社会积极推动建设气候治理公正转型制度体系,各国也在所制定的国家应对气候变化战略和规划中越来越多地提出与公正转型和就业相关的目标与措施。公正转型议题在国际气候治理进程中主流化的趋势给中国参与和引领全球气候治理带来了新的机遇与挑战。中国应加强关于该问题的基础性研究;在国内应对气候变化的行动中充分考虑该问题,保障受影响就业群体获得社会公正对待;总结具体实践经验;在政策领域协调上做好新的布局;积极参与《联合国气候变化框架公约》下公正转型治理体系的构建中。  相似文献   

基于Kriging方法的空间数据插值研究   总被引：11，自引：0，他引：11  

曾怀恩  黄声享 《测绘工程》2007,16(5):5-8

介绍了Kriging插值方法及其实质,提出一种变异函数理论模型参数估计的新方法,给出变异函数理论模型有效性评定的统计指标,并通过算例予以验证。最后,通过实例与反距离加权法相比较,证实Kriging插值的优越性。  相似文献   

Evolution of the Pearl River and its Implication for East Asian Continental Landscape Reversion     

ZHANG Hao  CUI Yuchi  QIAO Peijun  ZHAO Meng  XIANG Xuhong 《《地质学报》英文版》2021,95(1):66-76

As the link connecting the South China Continent and the northern South China Sea(SCS),the Pearl River is the focus of sedimentology and petroleum geology research.Its evolutionary process and controlling factors are of great significance in revealing the East Asian continental landscape reorganization during the Late Cenozoic.Based on published data,’source-to-sink’provenance analyses allow systematic deliberation on the birth and evolutionary history of the Pearl River.Close to the Oligocene/Miocene boundary,an abrupt shift in the sedimentary composition indicates significant westward and northward expansion of the river’s watershed area,followed by the establishment of a near-modern fluvial network.This sedimentary change generally concurred with a series of regional geological events,including the onset of the Yangtze throughflow,large-scale development of the loess plateau,and formation of the northwestern arid zone and Asian Monsoon system.These major changes in the geology-climate-ecoenvironment system are in close response to the process of the Cenozoic Xizang(Tibetan)Plateau uplift.Consequently,the East Asian continental landscape and most of midCenozoic drainage systems underwent critical reversion into east-tilting,or east-flowing networks.  相似文献   

实物地质资料二次开发利用在矿山深边部找矿中的作用          下载免费PDF全文

高建伟  任香爱  邓会娟  李秋玲  李英康  赵国春 《地质找矿论丛》2018,33(1):156-160

随着多年的开采,我国许多矿山成为危机矿山,外围及深部的找矿工作迫在眉睫。在前人研究的基础上,笔者总结了矿山二次利用实物地质资料进行找矿预测的方法,并将其归纳为成果及原始资料的重新分析、成矿预测方法的正确选择、实物地质资料的重新利用、找矿思路的重新确定、成矿规律的重新认识5个方面内容,以期望生产矿山加强实物地质资料二次开发力度,开辟深边部找矿的新局面。  相似文献   

“Source to Sink”: A Review of Tectonics-Erosion-Sedimentation Interactions in the Analogue Experiments of Accretionary WedgeEI北大核心CSCD     

Deng B.  Huang R.  Ma H.  He Y.  Lai D.  Jiang L.  Liu S. 《大地构造与成矿学》2018,(3):431-444

It is believed that the tectonics-erosion-sedimentation interaction in the analogue experiments was essentially improved by the theory of “from source to sink”. In particular, the widespread uplift and exhumation in the western China occurred in Cenozoic can be considered to be a typical natural laboratory in the world. Here we review our current understanding from tectonic sandbox models of tectonics-erosion-sedimentation and their interactions, as well as from natural laboratory. As we known, there are widespread erosion occurred predominantly at hinterland of the accretionary wedge, in contrast to the sedimentation occurred widely at foreland of the wedge. Therefore, fold-and-thrust belts with low syntectonic sedimentation and erosion would evolve in a self-similar fashion to produce a narrow accretionary wedge, while high syntectonic sedimentation and erosion would produce accretionary wedge with very active hinterland thrusts, and a large width. Furthermore, the critically tapered wedge model suggests that the crust-scale thrust-and-fold belts under a horizontal compressive force would come into a self-similar growth of a forward-tapering wedge when it reaches a critical taper angle of the combined angles of the base dip and the wedge slope. Such a process has important influence on the tectonics-erosion- sedimentation and their interactions both in accretionary wedges and their analogue experiments. Although there is a significant similarity between the analogue experiments and natural accretionary wedges in the surface processes of tectonics- erosion-sedimentation and their interactions, it is difficult to get more universal parameters between them. It should be noted that sandbox models of the accretionary wedges in the natural laboratory would improve significantly our understanding of the theory of the tectonics-erosion-sedimentation interactions and “from source to sink”. © 2018, Science Press. All right reserved.  相似文献   

准噶尔盆地南缘小渠子背斜T/P 同构造不整合几何学、运动学特征及地质意义   总被引：1，自引：0，他引：1       下载免费PDF全文

马德龙潘建国  张虎权王宏斌王彦君  魏彩茹陈雪珍 《地质科学》2018,(1):146-154

为探讨准噶尔盆地南缘二叠纪-三叠纪盆地构造性质及构造演化过程,笔者对盆地南缘小渠子背斜保存较完整的T/P 不整合进行了几何学、运动学和沉积韵律旋回特征的分析。T/P 不整合具有同构造不整合的特点,表现为不整合之下削蚀、之上超覆,是由于盆地南缘经历晚二叠世-早三叠世区域性挤压作用造成的。通过对小渠子地区深层地质结构的分析,认为晚二叠世-早三叠世的构造演化过程与早石炭世伸展断陷的反转密切相关。  相似文献   

改进IPAT等式的可持续性评价应用——以张掖市为例     

王肖波  徐中民 《冰川冻土》2018,40(5):1056-1064

综合的可持续评价是对地区经济发展的准确衡量,也是科学指导地区可持续发展的重要凭借。构建了一个基于IPAT等式改进的恒等式评价模型——IPADSEFÍÁ等式,以水资源在农业种植业方面的利用现状作为环境影响因素,综合考虑人口规模、经济增长、农业依赖度、农业产业结构、生产效益和先进农业技术应用等人文因素,结合1990-2014年的地区发展历程,对张掖的发展进程进行了分解和归因,并对发展的可持续性进行评价,得出张掖当前的发展模式对自然环境存在较强的压迫,尤其在水资源利用方面不是可持续的。而进行合理的产业结构调整、发展高附加值农业产业、继续加大应用先进农业技术可以缓解目前的水资源压力,让张掖的发展更具可持续性。  相似文献   

中国玛珥湖及其研究意义   总被引：4，自引：2，他引：2  

储国强  刘嘉麒 《岩石学报》2018,34(1):4-12

随着全球变化研究的深入,科学家们认识到古气候变化除轨道尺度的冰期/间冰期旋回之外还存在年代际-千年尺度的高频变化和突变事件。要认知这些变化,古气候记录的时间分辨率要达到"年-年代际"。因此,寻求时间跨度长、连续性好、信息丰富的高分辨率记录是过去全球变化研究面临的主要任务之一。玛珥湖为火山射汽喷发形成的封闭湖泊,由于其独特的形成机制及水文背景,使其能够提供数万年乃至几十万年连续稳定的沉积记录,是高分辨率古气候、古环境变化研究的重要对象。中国玛珥湖得天独厚,从热带到寒温带均有分布,为系统研究中国不同气候区各种时间尺度古气候变化规律提供了理想材料。本文基于中国玛珥湖的分布及沉积特征,探讨玛珥湖沉积记录能够为古全球变化研究做出怎样的贡献,解决什么科学问题,具体包括以下三个方面的内容:(1)在轨道尺度上,精确定位现代气候在地质历史中的位置是未来最具挑战性的科学问题之一。我国热带地区玛珥湖沉积物跨越了至少4个冰期-间冰期旋回,能够为理解冰期驱动机制、下一次冰期来临、高低纬关联等关键科学问题提供多学科数据;(2)千年尺度古气候变化,其成因可能源于不同的动力学机制,是气候系统对各种外部和内部驱动因子响应的结果,因此千年震荡可能存在明显的时空差异。集成不同气候带的玛珥湖沉积记录将为理解千年震荡规律及其驱动因子做出贡献;(3)年-年代际气候变化是预测未来气候变化的基础,PAGES、IPCC以及PAGES-Asia 2K均将过去2千年来气候变化作为预测未来几十年至百年尺度上重大全球变化的背景,并为此构建全球数据体系,玛珥湖沉积特别是纹层沉积记录能够填补某些地区高分辨率数据的空白。  相似文献