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61.
1945—1995年国际参考地磁场 总被引:1,自引:0,他引:1
本文回顾了国际参考地磁场(IGRF)的建立和修改过程;介绍了最新的IGRF模型,即第六代国际参考地磁场;综述了国际参考地磁场在地磁学中的应用,并指出了在使用过程中需要注意的一些问题. 相似文献
62.
63.
略论浊度标准,单位和测量仪器的研究与进展 总被引:4,自引:0,他引:4
本文阐述了国内外各行业所使用的浊度标准物质,计量单位,表达形式和单位换算以及各种不同设计原理的测量仪器研制进展概况,着重介绍了水质行业浊度标准物选定,浊度的测量和应有用并根据海洋环境浊度监测调查特点提出了几点认识。 相似文献
64.
简要总结了原城区导线网复测、更新状况,以及采用传统测量方法维护、更新城市导线网点存在的主要问题。采用GNSS RTK技术对中心城区加密控制网进行重新设计、布网和观测,根据相关改算公式对满足要求的点位进行改正,以满足加密控制测量的精度要求。通过实际应用,采用GNSS RTK施测方法进行城区加密控制测量是可行的。 相似文献
65.
Reference 3D是法国Spot立体卫星影像生成的DEM、ASTER DEM是高分辨率卫星成像设备—ASTER获取的立体影像生成的DEM,它们全球覆盖范围广、数据获取快、质量稳定。针对我国缺乏1:10000或1:5000基础地形资料的地区、难以获取资料的海外交通建设地区,本文探讨基于这两种DEM进行公路勘察设计。工程实践表明:Reference 3D相比ASTERDEM有着更高的精度,质量更加稳定可靠,可以满足公路勘察设计中规划、工可等阶段的需要,从而提高工作效率,缩短外业周期,降低成本。 相似文献
66.
地球重力场椭球谐模型的建立 总被引:2,自引:0,他引:2
本文以参考椭球面为边界来研究下列边值问题其中Σ是参考椭球面,γ是Somigliana正常重力,h是Σ的外法向。我们首先在保持扁率量级的前提下推导了问题(*)的简化形式,然后研究了求解的方法,最后讨论了建立椭球谐重力场模型的理论。 相似文献
67.
Monitoring Earth orientation using space-geodetic techniques: state-of-the-art and prospective 总被引:10,自引:10,他引:0
D. Gambis 《Journal of Geodesy》2004,78(4-5):295-303
Earth orientation parameters (EOPs) provide the transformation between the International Terrestrial Reference Frame (ITRF) and the International Celestial Reference Frame (ICRF). The different EOP series computed at the Earth Orientation Centre at the Paris Observatory are obtained from the combination of individual EOP series derived from the various space-geodetic techniques. These individual EOP series contain systematic errors, generally limited to biases and drifts, which introduce inconsistencies between EOPs and the terrestrial and celestial frames. The objectives of this paper are first to present the various combined EOP solutions made available at the EOP Centre for the different users, and second to present analyses concerning the long-term consistency of the EOP system with respect to both terrestrial and celestial reference frames. It appears that the present accuracy in the EOP combined IERS C04 series, which is at the level of 200 as for pole components and 20 s for UT1, does not match its internal precision, respectively 100 as and 5 s, because of propagation errors in the realization of the two reference frames. Rigorous combination methods based on a simultaneous estimation of station coordinates and EOPs, which are now being implemented within the International Earth Rotation Service (IERS), are likely to solve this problem in the future. 相似文献
68.
69.
Burša M. Kenyon S. Kouba J. Šíma Z. Vatrt V. Vojtíšková M. 《Studia Geophysica et Geodaetica》2004,48(3):493-502
A Global Vertical Reference Frame (GVRF) has been realized by means of several regional and local vertical datums (LVD) distributed world-wide: the North American Vertical Datum 1988 (NAVD 88), Australian Height Datum 1971 (AHD 71), LVD France, Institute Géographique National 1969 (IGN 69) and Brazilian Height Datum 1957 (BHD 57). The vertical shifts of the above LVD origins have been related to the adopted reference geopotential value W
0 = (62 636 856.0 ± 0.5) m2s–2 and they were determined at the 5 cm level. However, the W
0 reference value can be chosen arbitrarily, the methodology, which was developed here, does not require that the above value be adopted. 相似文献
70.
The Integrated Global Geodetic Observing System (IGGOS) viewed from the perspective of history 总被引:1,自引:0,他引:1
Towards the end of the 19th century, geodetic observation techniques allowed it to create geodetic networks of continental size. The insight that big networks can only be set up through international collaboration led to the establishment of an international collaboration called “Central European Arc Measurement”, the predecessor of the International Association of Geodesy (IAG), in 1864. The scope of IAG activities was extended already in the 19th century to include gravity.At the same time, astrometric observations could be made with an accuracy of a few tenths of an arcsecond. The accuracy stayed roughly on this level, till the space age opened the door for milliarcsecond (mas) astrometry. Astrometric observations allowed it at the end of the 19th century to prove the existence of polar motion. The insight that polar motion is almost unpredictable led to the establishment of the International Latitude Service (ILS) in 1899.The IAG and the ILS were the tools (a) to establish and maintain the terrestrial and the celestial reference systems, including the transformation parameters between the two systems, and (b) to determine the Earth's gravity field.Satellite-geodetic techniques and astrometric radio-interferometric techniques revolutionized geodesy in the second half of the 20th century. Satellite Laser Ranging (SLR) and methods based on the interferometric exploitation of microwave signals (stemming from Quasars and/or from satellites) allow it to realize the celestial reference frame with (sub-)mas accuracy, the global terrestrial reference frame with (sub-)cm accuracy, and to monitor the transformation between the systems with a high time resolution and (sub-)mas accuracy. This development led to the replacement of the ILS through the IERS, the International Earth Rotation Service in 1989.In the pre-space era, the Earth's gravity field could “only” be established by terrestrial methods. The determination of the Earth's gravitational field was revolutionized twice in the space era, first by observing geodetic satellites with optical, Laser, and Doppler techniques, secondly by implementing a continuous tracking with spaceborne GPS receivers in connection with satellite gradiometry. The sequence of the satellite gravity missions CHAMP, GRACE, and GOCE allow it to name the first decade of the 21st century the “decade of gravity field determination”.The techniques to establish and monitor the geometric and gravimetric reference frames are about to reach a mature state and will be the prevailing geodetic tools of the following decades. It is our duty to work in the spirit of our forefathers by creating similarly stable organizations within IAG with the declared goal to produce the geometric and gravimetric reference frames (including their time evolution) with the best available techniques and to make accurate and consistent products available to wider Earth sciences community as a basis for meaningful research in global change. IGGOS, the Integrated Global Geodetic Observing System, is IAG's attempt to achieve these goals. It is based on the well-functioning and well-established network of IAG services. 相似文献