天体运动的轨道偏心率研究概述---从恒星系统到行星系统

偏心率是描述天体运动轨道的重要参数之一, 能够为揭示天体的动力学演化提供重要线索, 进而帮助理解天体形成与演化的过程及背后的物理机制. 随着天文观测技术的不断发展, 人们对于天体运动轨道的研究已经走出太阳系, 包含的系统也从大质量端的恒星系统延伸到了低质量端的行星系统. 聚焦天体轨道偏心率研究, 回顾了目前在恒星系统(包括主序恒星、褐矮星以及致密星)和行星系统(包括太阳系外巨行星以及``超级地球''、``亚海王星''等小质量系外行星)方面取得的进展, 总结了不同尺度结构下偏心率研究的一些共同之处和待解决的问题. 并结合当下和未来的相关天文观测设备和项目, 对未来天体轨道偏心率方面的研究工作进行了展望.     

塔里木西缘晚新生代造山过程的记录——磨拉石建造及生长地层和生长不整合

通过对黄土高原洛川、长武剖面最近35万年来陆生蜗牛化石的高分辨率研究,揭示出喜温湿和喜冷干蜗牛种类分别存在不同的变化周期:喜温湿类蜗牛化石所揭示的东亚夏季风的变化存在明显的41 000a和23 000a周期,与地轴倾角和岁差(低纬度太阳辐射)的变化周期有关;而反映冬季风变化的喜冷干蜗牛种类则表现出不同的变化特点,其主要为0.1Ma和41 000a的周期.冬、夏季风的变化与地轴倾角41 000a周期都存在很好的相关性,但与地球轨道的岁差(19 000～23 000a)及偏心率(0.1Ma)的周期没有一致的相关关系.在轨道尺度上冬、夏季风之间不存在此消彼长的简单变化模式.     

泥河湾盆地基于粒度气候指标的轨道调谐时间标尺

泥河湾盆地东部出露一套厚近百米的以湖相为主的地层.我们测量了洞沟剖面的粒度和磁化率.通过磁化率记录的对比, 我们可以将前人确定的古地磁界线转移到我们的深度坐标上来, 并建立了初步的时间标尺.样品中粒径在20~50μm之间的颗粒含量时间序列可以与ETP曲线对比, 即低含量对应高ETP值.这样的对比意味着在北半球夏季太阳辐射量相对增加的时期, 进入泥河湾盆地沉积物中的风尘物质减少了.这与已知的北方风尘的演化历史是吻合的, 所以我们认为粒度(20~50μm) 含量是泥河湾盆地沉积物中比较可靠的古气候变化的替代性指标.对于沉积速率相对高的时段, 即 > 780ka的地层, 我们尝试用轨道调谐的方法建立了高分辨率的时间标尺.新的粒度(20~50μm) 含量时间序列滤波获得的20ka和41ka的周期成分与岁差及地轴倾斜度的理论值可以重合.这显示洞沟剖面的粒度(20~50μm) 含量记录可以作为轨道调谐的气候曲线.      

Quaternary biogenic opal records in the South China Sea: Linkages to East Asian monsoon, global ice volume and orbital forcing

Particulate fluxes investigated in the central South China Sea (SCS) during 1993―1996 indicate that opal flux can be used to show primary productivity change, which provides a foundation for tracing the evolutionary relationship between the surface productivity and East Asian monsoon in the SCS during the late Quaternary glacial and interglacial periods. Based on the studies of opal % and their mass accumulation rates (MAR) at the six sites recovered from the SCS during the “Resolution” ODP Leg 184 and “Sonne” 95 cruise of the Sino-Germany cooperation, opal % and their MARs increased evidently in the northern sites since 470―900 ka, and they enhanced and reduced, respectively, during the glacial and interglacial periods. Whereas they increased obviously in the southern sites since 420―450 ka, and they augmented and declined, respectively, during the interglacial and glacial periods. The vari- ability in opal % and their MARs in the late Quaternary glacial cyclicity indicate the “seesaw” pattern of surface productivity in the SCS. The winter monsoon intensified during the glacial periods, surface productivity increased and decreased, respectively, in the northern and southern SCS. The summer monsoon strengthened during the interglacial periods, surface productivity increased and decreased, respectively, in the southern and northern SCS. The cross spectral analyses between the opal % in the northern and southern SCS during the Quaternary and global ice volume (δ 18O) and orbital forcing (ETP) indicate that the East Asian winter and summer monsoons could be ascribed to the different drive mechanisms. On the orbital time scale, the global ice volume change could be a dominant factor for the winter monsoon intension and temporal variations. As compared with the winter monsoon, the correlative summer solar radiation with the obliquity and precession in the Northern Hemisphere could be a mostly controlling factor for the summer monsoon intension and temporal variations.     

Orbital imprint on Holocene palaeohydrological variations in west‐central Europe as reflected by lake‐level changes at Cerin (Jura Mountains,eastern France)

This paper presents a lake‐level record for the Holocene at Lake Cerin (Jura Mountains, eastern France). It is based on a range of sedimentological techniques validated in previous studies, with a combination of systematic lithostratigraphic investigations of the infillings accumulated in the lacustrine basin, and sediment analyses of two selected cores. The chronology is based on 10 radiocarbon dates and pollen stratigraphy. On a millennial scale, the Cerin lake‐level record shows three distinct successive phases characterised by higher lake‐level conditions until ca. 9000 cal. a BP, followed by a maximal lowering at ca. 9000–8500 cal. a BP, and a progressive rise until the present. This rise was punctuated by centennial‐scale fluctuations, with major events around 4000, 2800 and after 1500 cal. a BP. Considered on a multimillennial scale, the general pattern of palaeohydrological changes reconstructed at Cerin reflects the impact of orbitally driven summer insolation. This is in agreement with other regional and extra‐regional palaeoclimatic records, although every record shows peculiarities in timing and shape depending on the proxy used for reconstruction. In this general context, centennial to multicentennial oscillations appear to have been second‐order events in comparison with the major influence of the orbital factor. Copyright © 2011 John Wiley & Sons, Ltd.     

土星卫星的精密定轨方案

由于星际探测事业的发展,对土星卫星的定位精度要求愈来愈高,经典的分析法定轨方法已难以适应,在当今计算技术条件高度发展的背景下,本文给出了土星卫星的数值法定轨方案,采用了土星卫星运动的高精度力学模型,并运用１８７４－１９８９这１００多年间的观测资料,引用现代最小二乘估计,对土星卫生进行精密定轨。该方案可以在引用同样的力学模型的前提下,对土星各颗卫星进行定轨,亦可同时进行多颗卫星的定轨。相应的软件比较     

近地小行星轨道演化的研究

本文主要阐述了近年来我们在近地小行星轨道演化研究所获得的一些基本结果,即合理的力学模型和相应的有效算法,并以实际预报算例与有关权威性的结果作了比较,证实这些研究结果确实是可信的。     

Responses of foraminiferal isotopic variations at ODP Site 1143 in the southern South China Sea to orbital forcing

1 Astronomical theory One of the greatest achievements of the EarthSciences in the 20th century is the establishment of theMilankovitch theory or the astronomical theory[1]. AsImbrie pointed out[2], the astronomical theory can bedescribed as a simple system model. The input to thesystem can be defined as changes in the geometry ofthe Earth’s orbit or the seasonal and latitudinal distri-bution of incoming solar radiation, whereas the outputto the system can be defined as one or more calc…     

GPS/VRS实时网络改正数生成算法研究

为提高厘米级网络GPS/VRS实时动态定位的精度和可靠性,系统地探讨VRS网络实时改正数的生成模型,并提出适用于中长距离参考站网络的电离层、对流层以及卫星轨道改正数计算的改进算法。结合四川GPS参考站网络(SGRSN)以及自主开发的虚拟参考站软件平台VENUS系统,对上述改正数生成算法进行试验验证,结果表明其大气误差改正数精度为2~4 cm,轨道误差的影响可基本消除,满足80 km以上中长距离稀疏参考站网络厘米级实时动态定位服务要求。