Modeling the WMAP large-angle anomalies as an effect of a local density inhomogeneity

We investigate large-angle scale temperature anisotropy in the Cosmic Microwave Background (CMB) with the Wilkinson Microwave Anisotropy Probe (WMAP) data and model the large-angle anomalies as the effect of the CMB quadrupole anisotropies caused by the local density inhomogeneities. The quadrupole caused by the local density inhomogeneities is different from the special relativity kinematic quadrupole. If the observer inhabits a strong inhomogeneous region, the local quadrupole should not be neglected. We ...     

多层湍流大气相位屏的数值模拟

高分辨图像重建技术可以有效消除湍流大气的影响,重建目标的接近望远镜衍射极限的图像。但是当目标的视场角比较大时,大气—望远镜综合系统不再是线性空不变的,给图像重建带来新的困难,它是大气性质中的一个重要特性,对大气相位屏的模拟应该满足这一特性。提出了一种可以模拟等晕区效应的多层大气相位屏的数值模拟方法,这种方法可以应用于等晕区对高分辨统计重建方法的影响的研究中。利用该数值模拟方法模拟了5″和8″的双星的斑点图,用斑点干涉术对模拟的双星进行了重建,并与实测的双星的斑点干涉术重建结果进行了比较。比较结果表明该数值模拟方法所产生的等晕区效应与实际的等晕区效应相似。     

大气对532nm激光影响在漫反射激光测距中的应用

激光光束在大气中的传输是与大气特征有关的,如大气湍流、大气散射与吸收,而且激光测距的回波除了与距离有关外,其回波数及精度也与大气特征相关。漫反射激光测距的目标是低轨空间碎片,在一定反射截面的条件下,应用一定功率的激光进行地面靶板漫反射测距试验,以确定多少功率的激光器可实现空间碎片的漫反射测距,这时地面靶的距离选取应该具有代表性,它代表了在一定斜程下穿过整个大气层的效应。通过对大气湍流和大气衰减对激光传输的影响进行分析,理论上计算出在低轨目标为400km时,漫反射激光测距试验地面靶的水平距离该取多远时才能代表在一定斜程下穿过400km大气层的效应,从而为漫反射激光测距试验地面靶距离的选取提供参考依据。     

行星际闪烁单站单频数据处理

太阳风是日地空间的主要物质来源,太阳风的观测对日地空间环境及地球物理的研究具有重要意义。地基行星际闪烁观测是监测太阳风风速,测量太阳风等离子体不规则结构,研究遥远致密射电源角径的重要且有效的方法。介绍了行星际闪烁地基观测的单站单频模式的基本理论,针对单站单频模式观测的数据处理及自编软件。本文的工作是为行星际闪烁单站双频系统数据分析处理作前期准备。     

Biogenic Sediments and Their Paleoceanographic Implication in West Pacific Warm Pool during the Pleistocene

Primary productivity has played an important role in the global carbon cycle during the Quaternary. The average Corg/N ratio was 7.0 from the core MD97-2140 in the West Pacific Warm Pool (WPWP) over the last 1 755 ka, which indicates a main contribution of marine organic carbon to the organic matter in the sediments. Large fluctuations in mass accumulation rates (MARs) of biogenics and lithogenics from this core since the marine isotope stage (MIS) 6 reflected the moderate variability in oceanographic condi...     

Glacier Changes at Svartisen,Northern Norway,during the Last 125 Years:Influence of Climate and Other Factors

The two ice caps of Svartisen,at the latitude of the Arctic Circle in Norway,supply 60 glaciers,ranging in size from >50 to <1 km2.Until the last two decades of the 19th century,the glaciers remained close to their maximum recent(Little Ice Age) size.In response to the prevailing 20th century climate,they have become smaller,but the changes have varied between glaciers.Climatic factors have not been the sole control of the variations.The response times of small,steep glaciers are shorter than those of the l...     

Characteristics and Environmental Significance of pH and EC in Summer Rainfall and Shallow Firn Profile at Yulong Snow Mountain,Lijiang City,China

The seasonal and inter-annual variations of pH and EC(electrical conductivity) at Yu-long(玉龙) Snow Mountain,Lijiang(丽江) City,are sensitive to precipitation variations and are important indicators of the atmospheric environment.The pH of summer rainfall at Lijiang City ranges from 6.7 to 7.4,and alkaline mineral salts dominate the variations of rainfall acidity.pH values in theshallow firn profile at Baishui(白水) Glacier No.1 range from 5.6 to 6.3,and EC values from 2.4 to 7.3 μs/cm.The ranges are lower than ...     

Observed Glaciohydrological Changes in China's Typical Monsoonal Temperate Glacier Region since 1980s

Under the background of significant climate warming since the 1980s,the glaciers in China's monsoonal temperate glacier region respond to the warming intensely.Based on the glaciohy-drological observations at some typical glaciers from Mts.Yulong(玉龙) and Gongga(贡嘎) of Heng-duan(横断) Mountains Range in the southeastern Tibetan plateau,the glaciohydrological changes in the temperate glacier region since the 1980s were investigated.First,the glacier terminus exhibited an accelerating retreat.Second,as the glaci...     

Detrital Zircon Geochronology and Provenance of Core Sediments in Zhoulao Town,Jianghan Plain,China

In our study,the U-Pb age spectrum of detrital zircons from terrigenous sediments is used to determine the sources.The Middle and Upper Reaches of the Yangtze River drain the western Yangtze craton and eastern Tibetan plateau,and take lots of sediments to the Jianghan (江汉) plain.Detrital zircons collected from Zhoulao (周老) core provide an ideal sample for the provenance studies.Here we report LA-ICP-MS U-Pb ages of 125 detrital zircons from one sand sample in the core sediments,which is recovered from a dep...     

Modeling the Contemporary Stress Field and Deformation Pattern of Eastern Mediterranean

The contemporary stress field in the earth's crust is important and provides insights into mechanisms that drive plate motions.In this study,elastic plane stress finite element modeling incorporating realistic rock parameters was used to calculate the stress field,displacement field,and deformation of the plate interactions in the eastern Mediterranean.Modeled stress data for the African-Arabian-Anatolian plate interactions with fixed European platform correlate well with observed contemporary stress indica...