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1.
垂线偏差时间变化的精度估计 总被引：3，自引：0，他引：3
对于利用Vening-Meinesz微分公式计算垂线偏差随时间变化的测定精度进行了初步估计。通过对地形改正项的影响、代表误差的影响、远区域重力异常的影响等3种主要误差的分析和实际估计，论证了它们对计算结果的综合影响不超过0.01″，比铅垂线的时间变化0.1″要高一个量级。因此认为重力方法在实践中是可行的。 相似文献
2.
地壳均衡假说与湘西北地壳均衡失调探讨 总被引：2，自引：0，他引：2
由湖南省1:100万10′×15′平均均衡重力异常图知,湘西北地区呈重力高;除此以外的广大地区,当消除花岗岩对应的局部重力低外,均衡异常基本呈零值特征。笔者认为这是湖南全省的地壳均衡失调区,并从5个方面对该问题进行了分析。 相似文献
3.
H. Abd-Elmotaal 《Journal of Geodesy》2000,74(5):390-398
Inverse problems in isostasy will consist in making the isostatic anomalies to be zero under a certain isostatic hypothesis.
In the case of the Vening Meinesz isostatic hypothesis, the density contrast is constant, while the Moho depth (depth of the
Mohorovičić discontinuity) is variable. Hence, the Vening Meinesz inverse isostatic problem aims to determine a suitable variable
Moho depth for a prescribed constant density contrast. The main idea is easy but the theoretical analysis is somewhat difficult.
Moreover, the practical determination of the variable Moho depths based on the Vening Meinesz inverse problem is a laborious
and time-consuming task. The formulas used for computing the inverse Vening Meinesz Moho depths are derived. The computational
tricks essentially needed for computing the inverse Vening Meinesz Moho depths from a set of local and global Bouguer anomalies
are described. The Moho depths for a test area are computed based on the inverse Vening Meinesz isostatic problem. These Moho
depths fit the Moho depths derived from seismic observations with a good accuracy, in which the parameters used for the fitting
agree well with those determined geophysically.
Received: 4 February 1999 / Accepted: 4 October 1999 相似文献
4.
联合TOPEX/Poseidon,ERS2和Geosat卫星测高资料确定中国近海重力异常 总被引：12，自引：3，他引：12
处理了 TOPEX/Poseidon(第 9周期至第 2 4 9周期 ) ,ERS2 (第 0周期至第 44周期 )和Geosat/GM(第 1周期至第 2 5周期 )以及 Geosat ERM(第 1周期至第 66周期 )卫星测高资料 ,求解了各自卫星任务的交叉点和垂线偏差 ,利用逆 Vening- Meinesz公式确定了 2 .5′×2 .5′中国近海海洋重力异常 ,并与我国南海船测重力异常作了比较 ,其精度为± 9.3m Gal( 1 Gal=1 cm/s2 )。本文同时导出了严密的 2维平面卷积公式 ,它与 1维严密卷积公式计算结果差值的标准差为± 0 .1 m Gal,而 2维球面公式为± 0 .5 m Gal 相似文献
5.
Mohammad Bagherbandi 《Journal of Asian Earth Sciences》2012,43(1):89-97
Crustal thickness can be determined by gravimetric methods based on different assumptions, e.g. by isostatic hypotheses. Here we compare three gravimetric inversion methods to estimate the Moho depth. Two Moho models based on the Vening Meinesz-Moritz hypothesis and one by using Parker-Oldenburg’s algorithm, which are investigated in Tibet plateau. The results are compared with CRUST2.0, and it will be presented that the estimated Moho depths from the Vening Meinesz-Moritz model will be better than the Parker-Oldenburg’s algorithm. 相似文献
6.
本文基于Vening Meinesz区域均衡模型,通过试验不同参数计算Vening Meinesz均衡补偿深度,将其与CRUST1.0模型给出的莫霍面深度进行拟合,得到适应于天山及邻区的平均补偿深度、"地区性指标"以及区域补偿半径.结合地球重力场模型EIGEN-6C4与地形数据,利用球冠体积分方法进行地形效应、沉积层效应计算和均衡校正,得到了研究区的Vening Meinesz均衡重力异常.结果显示天山及邻区的均衡重力异常幅值在-110~120 mGal之间,表明了天山及周边盆地岩石圈所处于的均衡状态,同时揭示了研究区的壳幔密度分布特征.天山、塔里木盆地、准噶尔盆地等块体的地壳垂向形变可能部分地由均衡调整引起,且均衡调整趋势与地面形变测量结果相契合.通过对均衡重力异常成因的解释,从地壳均衡角度分析了该地区复杂的构造背景及其新生代以来的演化历程. 相似文献
7.
Global mean sea surface heights (SSHs) and gravity anomalies on a 2′×2′ grid were determined from Seasat, Geosat (Exact Repeat Mission and Geodetic Mission), ERS-1 (1.5-year mean of 35-day, and
GM), TOPEX/POSEIDON (T/P) (5.6-year mean) and ERS-2 (2-year mean) altimeter data over the region 0∘–360∘ longitude and –80∘–80∘ latitude. To reduce ocean variabilities and data noises, SSHs from non-repeat missions were filtered by Gaussian filters
of various wavelengths. A Levitus oceanic dynamic topography was subtracted from the altimeter-derived SSHs, and the resulting
heights were used to compute along-track deflection of the vertical (DOV). Geoidal heights and gravity anomalies were then
computed from DOV using the deflection-geoid and inverse Vening Meinesz formulae. The Levitus oceanic dynamic topography was
added back to the geoidal heights to obtain a preliminary sea surface grid. The difference between the T/P mean sea surface
and the preliminary sea surface was computed on a grid by a minimum curvature method and then was added to the preliminary
grid. The comparison of the NCTU01 mean sea surface height (MSSH) with the T/P and the ERS-1 MSSH result in overall root-mean-square
(RMS) differences of 5.0 and 3.1 cm in SSH, respectively, and 7.1 and 3.2 μrad in SSH gradient, respectively. The RMS differences
between the predicted and shipborne gravity anomalies range from 3.0 to 13.4 mGal in 12 areas of the world's oceans.
Received: 26 September 2001 / Accepted: 3 April 2002
Correspondence to: C. Hwang
Acknowledgements. This research is partly supported by the National Science Council of ROC, under grants NSC89-2611-M-009-003-OP2 and NSC89-2211-E-009-095.
This is a contribution to the IAG Special Study Group 3.186. The Geosat and ERS1/2 data are from NOAA and CERSAT/France, respectively.
The T/P data were provided by AVISO. The CLS and GSFC00 MSS models were kindly provided by NASA/GSFC and CLS, respectively.
Drs. Levitus, Monterey, and Boyer are thanked for providing the SST model. Dr. T. Gruber and two anonymous reviewers provided
very detailed reviews that improved the quality of this paper. 相似文献
8.
利用多种测高数据反演中国南海海域重力异常 总被引：1，自引：0，他引：1
联合Geosat/GM、ERS-1/168和Envisat 3种测高数据,基于高精度地球重力模型EGM2008,采用垂线偏差方法和逆Vening-Meinesz公式,利用移去-恢复技术确定了中国近海及邻近海域(0°N～42°N,102°E～138°E)分辨率为2′×2′的重力异常.在中国南海海域,测高重力异常与船测重力... 相似文献
9.
Wavelet evaluation of the Stokes and Vening Meinesz integrals 总被引：1，自引：0，他引：1
The wavelet transform is a powerful tool in evaluating some singular geodetic integrals. Due to its localization properties in both the time (space) and frequency (scale) domains, and because the kernels of some geodetic integrals have singular points and decay smoothly and quickly away from the singularities, many wavelet transform coefficients of the kernels become zeros or negligible, and only a small number of wavelet transform coefficients are significant. It is thus possible to significantly compress the kernels of these integrals on a wavelet basis by neglecting the zero coefficients and the small coefficients below a certain threshold. Therefore, wavelets provide a convenient way of efficiently evaluating these integrals in terms of fast computation and savings of computer memory. A modified algorithm for the wavelet evaluation of Stokes' integral is presented. The same modified algorithm is applied to the evaluation of the Vening Meinesz integral, whose kernel has a stronger singularity than does Stokes' kernel. Numerical examples illustrate the efficiency and accuracy of the wavelet methods.Acknowledgments.The author express their sincere thanks to Dr. Salamonwicz for providing his PhD thesis. E-mail correspondence between the authors and Dr. Barthelmes and Dr. Benciolini contributed to the work. R. Benciolini and the other two anonymous reviewers are thanked for their constructive comments. Support for this research was provided by research grants to Dr. Sideris from the Natural Sciences and Engineering Reserch Council of Canada (NSERC) and the Geomatics for Informed Decisions (GEOIDE) Network of Centres of Excellence. The MATLAB Wavelet Toolbox package was used as the platform to develop the software in this project. 相似文献
10.
A computational scheme using the wavelet transform is employed for local geoid determination, where wavelet multiresolution analysis (MRA) is introduced as an alternative approach to the well-established fast Fourier transform (FFT). The Stokes and Vening Meinesz integrals are approximated in finite MRA subspaces. The algorithm is built using an orthogonal wavelet base function. The characteristics of the base function and its effect on the final result are investigated. Hard and soft thresholding are tested in the compression of the kernel as well as global thresholding is compared to level-wise thresholding to optimize the compression level with an acceptable accuracy. Both global and level-wise thresholding are combined in order to achieve the maximum compression level, with acceptable geoid accuracy. The compression rate depends on the degree of singularity of the kernel. In the case of Stokes, a 94 per cent compression level is achieved with 1 cm (rms) accuracy in comparison to FFT and numerical integration approaches. Due to its stronger singularity, in the case of the Vening Meinesz kernel, 97 per cent compression rate is achieved with a 0.07 arc-second (rms) accuracy. The compression percentages achieved in this study are higher than those reported in pervious studies, which shows that this algorithm is very suitable for use in local geoid determination. 相似文献