极移对地面重力及大地水准面的影响     

华仲春 《测绘学院学报》1989,(1)

地球自转轴的变动必然会导致地面重力值及大地水准面的变动。本文导出了这些变动的简便计算公式。计算结果表明,极移引起的地面重力变化最大达15μgal;大地水准面高的变化最大达5cm;垂线偏差的变化最大达0.003。这些量对目前及将来高精度大地测量产生的影响是不可忽视的。  相似文献   

The Use of Second-generation Wavelets to Combine a Gravimetric Quasigeoid Model with GPS-levelling Data     

A. Soltanpour  H. Nahavandchi  W. E. Featherstone 《Journal of Geodesy》2006,80(2):82-93

The merging of a gravimetric quasigeoid model with GPS-levelling data using second-generation wavelets is considered so as to provide better transformation of GPS ellipsoidal heights to normal heights. Since GPS-levelling data are irregular in the space domain and the classical wavelet transform relies on Fourier theory, which is unable to deal with irregular data sets without prior gridding, the classical wavelet transform is not directly applicable to this problem. Instead, second-generation wavelets and their associated lifting scheme, which do not require regularly spaced data, are used to combine gravimetric quasigeoid models and GPS-levelling data over Norway and Australia, and the results are cross-validated. Cross-validation means that GPS-levelling points not used in the merging are used to assess the results, where one point is omitted from the merging and used to test the merged surface, which is repeated for all points in the dataset. The wavelet-based results are also compared to those from least squares collocation (LSC) merging. This comparison shows that the second-generation wavelet method can be used instead of LSC with similar results, but the assumption of stationarity for LSC is not required in the wavelet method. Specifically, it is not necessary to (somewhat arbitrarily) remove trends from the data before applying the wavelet method, as is the case for LSC. It is also shown that the wavelet method is better at decreasing the maximum and minimum differences between the merged geoid and the cross-validating GPS-levelling data.  相似文献   

Quasigeoid evaluation with improved levelled height data for Norway     

D. I. Lysaker  O. C. D. Omang  B. R. Pettersen  D. Solheim 《Journal of Geodesy》2007,81(9):617-627

GPS-levelling points are widely used to control gravimetric geoid or quasigeoid models. Direct comparison is often interpreted to reveal the accuracy of the gravimetric model, using GPS-levelling as a reference. However, both GPS and levelled heights contain errors, and in order to achieve a centimeter-accuracy geoid, these should be investigated. The Norwegian Height System NN1954 is known to contain large systematic errors due to postglacial land uplift in the area. In this study, the current height system and two revised versions, corrected for uplift, are applied to compute three sets of control quasigeoid heights in the southern part of Norway. These heights are then compared to various Nordic gravimetric quasigeoid models generated during the last two decades. In contradiction to some earlier studies, the accuracy of gravimetric quasigeoid models for this area are found to improve near-linearly with time. This is in accordance with expectations, since both data coverage and computation methods have progressed during this time. However, this study shows the importance of establishing accurate and error-free control data for geoid comparisons.  相似文献   

The spheroidal fixed–free two-boundary-value problem for geoid determination (the spheroidal Bruns' transform)     

E. W. Grafarend  A. Ardalan  M. G. Sideris 《Journal of Geodesy》1999,73(10):513-533

The target of the spheroidal Gauss–Listing geoid determination is presented as a solution of the spheroidal fixed–free two-boundary value problem based on a spheroidal Bruns' transformation (“spheroidal Bruns' formula”). The nonlinear spheroidal Bruns' transform (nonlinear spheroidal Bruns' formula), the spheroidal fixed part and the spheroidal free part of the two-boundary value problem are derived. Four different spheroidal gravity models are treated, in particular to determine whether they pass the test to fit to the postulate of a level ellipsoidal gravity field, namely of Somigliana–Pizzetti type. Received: 4 May 1999 / Accepted: 21 May 1999  相似文献   

一种新型重力测量卫星系统确定全球重力场的性能分析   总被引：1，自引：0，他引：1       下载免费PDF全文

徐新禹  姜卫平  张晓敏  周晓青  丁延卫  朱广彬 《地球物理学报》2018,61(6):2227-2236

本文设计了一种高-低卫星跟踪卫星、低-低卫星跟踪卫星和卫星重力梯度测量相结合的新型重力测量卫星系统,其可在一定程度上发挥卫星重力梯度和低低卫星跟踪卫星两种测量模式各自的优势.基于重力卫星系统指标设计的半解析法,深入分析了不同重力测量卫星系统配置和不同观测量及其不同白噪声水平情况下,新型卫星重力测量模式反演重力场模型的能力.数值模拟分析结果表明：在观测值精度和星间距离相同的条件下,轨道高度是影响重力场反演精度的关键因素;随着星间距离的增大,高频重力场信号反演精度会先提高后降低,轨道高度在200~350 km之间时,星间距离在150~180 km之间时反演精度最优;星间距离变率和卫星重力梯度两类观测值仅在某些精度配置时可达到优势互补,如果某一类观测值精度很高,则另一类观测值在联合解算时贡献非常小或者没有贡献.在300 km轨道高度,若以GRACE和GOCE任务的设计指标1 μm·s^-1/√Hz和5 mE/√Hz来配置新型重力测量卫星系统中星间距离变率和引力梯度观测值的精度,联合两类观测值解算200阶次模型大地水准面的精度比独立解算分别提高1.2倍和2.8倍.如果以实现100 km空间分辨率1~2 cm精度大地水准面为科学目标,考虑卫星在轨寿命,建议轨道高度选择300 km,星间距离变率和卫星重力梯度的精度分别为0.1 μm·s^-1/√Hz和1 mE/√Hz.本文的研究成果可为中国研制自主的重力测量卫星系统提供参考依据.  相似文献   

The GEOID96 high-resolution geoid height model for the United States   总被引：4，自引：0，他引：4  

D. A. Smith  D. G. Milbert 《Journal of Geodesy》1999,73(5):219-236

The 2 arc-minute × 2 arc-minute geoid model (GEOID96) for the United States supports the conversion between North American Datum 1983 (NAD 83) ellipsoid heights and North American Vertical Datum 1988 (NAVD 88) Helmert heights. GEOID96 includes information from global positioning system (GPS) height measurements at optically leveled benchmarks. A separate geocentric gravimetric geoid, G96SSS, was first calculated, then datum transformations and least-squares collocation were used to convert from G96SSS to GEOID96. Fits of 2951 GPS/level (ITRF94/NAVD 88) benchmarks to G96SSS show a 15.1-cm root mean square (RMS) around a tilted plane (0.06 ppm, 178^∘ azimuth), with a mean value of −31.4 cm (15.6-cm RMS without plane). This mean represents a bias in NAVD 88 from global mean sea level, remaining nearly constant when computed from subsets of benchmarks. Fits of 2951 GPS/level (NAD 83/NAVD 88) benchmarks to GEOID96 show a 5.5-cm RMS (no tilts, zero average), due primarily to GPS error. The correlated error was 2.5 cm, decorrelating at 40 km, and is due to gravity, geoid and GPS errors. Differences between GEOID96 and GEOID93 range from −122 to +374 cm due primarily to the non-geocentricity of NAD 83. Received: 28 July 1997 / Accepted: 2 September 1998  相似文献   

Improved convergence rates for the truncation error in gravimetric geoid determination   总被引：2，自引：2，他引：0  

J. D. Evans  W. E. Featherstone 《Journal of Geodesy》2000,74(2):239-248

 When Stokes's integral is used over a spherical cap to compute a gravimetric estimate of the geoid, a truncation error results due to the neglect of gravity data over the remainder of the Earth. Associated with the truncation error is an error kernel defined over these two complementary regions. An important observation is that the rate of decay of the coefficients of the series expansion for the truncation error in terms of Legendre polynomials is determined by the smoothness properties of the error kernel. Previously published deterministic modifications of Stokes's integration kernel involve either a discontinuity in the error kernel or its first derivative at the spherical cap radius. These kernels are generalised and extended by constructing error kernels whose derivatives at the spherical cap radius are continuous up to an arbitrary order. This construction is achieved by smoothly continuing the error kernel function into the spherical cap using a suitable degree polynomial. Accordingly, an improved rate of convergence of the spectral series representation of the truncation error is obtained. Received: 21 April 1998 / Accepted: 4 October 1999  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987112000333     

G.F.Ufimtsev 《地学前缘(英文版)》2012,3(5):559-569

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准噶尔盆地中西部油区精化似大地水准面建立与实施     

程引录  薛民 《测绘与空间地理信息》2011,34(4):226-228

利用GPS定位技术结合准噶尔盆地区域内的重力资料、水准资料、高分辨率的地形数据以及最新的重力场模型,精确研究并确定准噶尔盆地的似大地水准面模型,以求取不同地区、不同位置高精度的高程异常值,从根本上解决GPS定位技术无法直接提供正常高的问题。  相似文献   

南极冰盖的形成与消融对全球大地水准面与海面的影响     

张赤军  陆洋 《海洋与湖沼》1998,29(1):104-108

采用球函数表征了南极冰川覆盖的高度,并运用位理论与地壳均衡观念,研究了南极冰盖形成、消融对大地水准面与相对海面的影响。结果表明,冰盖形成后的大地水难面发生了明显变化,在南极为＋115m,在南纬25°带上为－37m,在北极为＋8m;若地壳为弹性固体而地幔为流体,设地慢密度为3270kg／m3,则在冰川消融、地壳均衡调整后的沿海大陆相对海面的变化仅为2．8m。  相似文献