Observed and simulated features of the CO2 diurnal cycle in the boundary layer at Beijing and Hefei,China

The mechanism of the CO2diurnal cycle is a basis for investigating the carbon budget and its impacts on climate and environment change.Regional diurnal variations in CO2concentration based on observations and modeling have been studied widely.However,few studies have focused on the pattern of the CO2diurnal cycle in China.In this study,a three-dimensional global chemical transport model,Goddard Earth Observing System(GEOS)-Chem,was applied to simulate the CO2concentration and its variation over China from 2004 to 2012.Meanwhile,we also analyzed the CO2concentration as observed by two eddy covariance flux observation towers,one located in Beijing(39°580N,116°220E)and one in Hefei(31°550N,117°100E),using LI-COR 7500A infrared gas analyzers.Observations showed the amplitude of the CO2diurnal cycle at Hefei to be larger than at Beijing,due to stronger ecological activities.GEOS-Chem successfully captured the main aspects of the diurnal cycle of the CO2concentration in the boundary layer observed at both Beijing and Hefei.However,some discrepancies between the model and observations did exist;specifically,the model tended to underestimate the amplitude of the CO2diurnal cycle.The data also showed that traffic emissions significantly enhanced the CO2concentration in the boundary layer.     

Precise determination of the reference point coordinates of Shanghai Tianma 65-m radio telescope

A local survey was implemented at the newly constructed Shanghai Tianma 65-m radio telescope. In this article, the survey implementation and data analysis are described. Particularly, by application of coordinate transformation, dimensionality reduction and step fitting of parameters, as well as adoption of reliability test measures of parameters, the mathematical model of data analysis is simplified, the detrimental effects of observation noises and unevenly spatial coverage of sample points are effectively compressed, the stability and precision of parameter solutions are improved, and so the geocentric three-dimensional coordinates of the reference point of this telescope in the precision of millimeters were determined, and the axisoffset was shown not significant on the precision level of 3 mm. The outcome provides important reference to the subsequent activities of antenna maintenance and scientific application, including the establishment of precise antenna orientation model, orientation guidance, fringe searching in data cross-correlation, analysis and application studies of VLBI observations. It is also important archive data for monitoring possible subsidence and lateral displacement of antenna foundation as well as deformation of antenna tracking-rail and structure.     

那些吸引人类奔月的理由

正新一轮的"月球热"背后,除了满足人们对这个神秘星球的数千年认识的渴望之外,当然还有十足的科学理由人类自古就曾无数次幻想去拜访地球最近的邻居——月球。自上世纪50年代末以来,苏联和美国就开始在探月研究方面的太空竞赛,最终阿波罗飞船于1969年成功登月,"迈出了人类的一大步",书写了人类在探月进程中辉煌的一     

预测修正下的动态数据传送机制

利用无线传感器网络中节点感知数据的相关性,提出了一种基于预测修正的动态数据传送机制.核心思想是:将数据预测与模型计算分离,接收节点先对数据进行平稳化处理,然后建立模型或动态更新模型,再把模型参数发送给采样节点.采样节点用精简的预测修正算法预测数据,通过比较法确定需要发送的采样数据,从而减少了数据传送的次数,延长了网络的生命期.仿真结果表明,所提算法可以滤除真实采样观测序列中83%的冗余数据,预测精度较一般预测算法提高了22%,它适用于能量约束性较强的无线传感器网络.     

空间对地观测技术发展及应用

介绍了对地观测技术的国外发展情况,从国家安全的角度分析了对地观测技术的发展趋势;接着结合国内对地观测技术发展现状,分析了我国对地观测系统发展存在的差距,从对地观测对国家安全的重要作用出发提出了启示和建议。对地观测系统可以满足面向各种应用的对陆地、海洋、大气等各个层面的全方位、立体观测信息需求,在维护国家安全、促进经济建设和推动技术发展等诸多方面发挥着越来越重要的作用。     

浅析软土路基施工中监控要点及沉降

本文结合洛湛铁路永洪段建设工程项目中监理单位在软土路基施工过程中的监控要点进行阐述,对软土路基的沉降观测进行分析和评价：洛湛铁路永洪段软土路基处理中,对软土路基进行沉降稳定观测,观测统计表明,通过对软基进行处理,严格按规范要求施工,其工程质量是能够达到预期目标的。     

黄海海洋观测研究站建设工作取得重要进展

日前,由中科院海洋所承担的“中国科学院近海海洋观测研究网络一黄海海洋观测研究站”建设工作取得重要进展。科研人员先后二次进行了黄海海洋观测研究站区域地质环境勘查与北黄海海洋生态环境多要素调查,采集了大量数据和样品,初步绘制了建设区域海底地形地貌图,标志着黄海海洋观测研究站建设工作与数据采集和积累工作已正式开始。     

对地观测中心成功接收并处理RADARSAT-2卫星数据

对地观测与数字地球科学中心 10月14日18时38分,中国科学院对地观测与数字地球科学中心成功接收了RADARSAT-2卫星向我国发送的第一轨数据,这标志这我国在接收国际民用高分辨率合成孔径雷达卫星数据方面又向前跨进了一大步。数据随即由位于密云县的卫星接收部通过高速网络传送到北京,并实现了高质量的成像处理。     

基于新息序列的多维MA(q)模型适时递推预测

利用Hilbert空间中正交投影的有关理论,给出并证明了最佳线性预测在内积定义下的一个定理,以此作为适时递归预测的基础.讨论了新息递归算法的理论和方法,将新息算法运用于多维MA(q)模型的预测问题.利用有穷观测值导出并证明了多维MA(q)模型的任意l步适时递归预测公式.     

黄土塬区特殊观测系统的设计及应用

针对黄土塬地表复杂的特点,设计了符合该区施工特点的特殊三维地震观测系统,在施工过程中及时进行了炮检点的实时动态设计分析,采用激发点的灵活布设、检波排列的适度调整,较好地解决了CDP的分布以及资料的完整性问题。通过该方法的应用,首次获取了吕梁山脉中段西部一个典型的黄土源区地震反射资料,进而探索出了一套适合低信噪比、地表极其复杂的三维地震采集技术。