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1.
Energy integral method for gravity field determination from satellite orbit coordinates 总被引:21,自引:1,他引:21
A fast iterative method for gravity field determination from low Earth satellite orbit coordinates has been developed and implemented successfully. The method is based on energy conservation and avoids problems related to orbit dynamics and initial state. In addition, the particular geometry of a repeat orbit is exploited by using a very efficient iterative estimation scheme, in which a set of normal equations is approximated by a sparse block-diagonal equivalent. Recovery experiments for spherical harmonic gravity field models up to degree and order 80 and 120 were conducted based on a 29-day simulated data set of orbit coordinates. The method was found to be very flexible and could be easily adapted to include observations of non-conservative accelerations, such as (to be) provided by satellites like CHAMP, GRACE, and GOCE. A serious drawback of the method is its large sensitivity to satellite velocity errors. Existing orbit determination strategies need to be altered or augmented to include algorithms that focus on optimizing the accuracy of estimated velocities. 相似文献
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缺乏有效的大地水准面成果精度评估方法,是高程基准现代化及其成果应用面临的关键问题。本文基于GNSS水准高程异常与重力场频域误差特性,研究GNSS水准与重力地面高程异常融合的技术要求,进而提出一种大地水准面成果的误差表达与精度评估方法。经示例测试分析,得出主要结论如下:①实用地面高程异常(即融合后的似大地水准面)精度,应采用随距离非线性变化的高程异常差误差曲线表达;②似大地水准面的精度评估,推荐采用两项误差指标和两条误差曲线共4个要素完整表达,即重力地面高程异常差误差、实用地面高程异常内部误差、实用地面高程异常差误差曲线与GNSS水准高程异常差误差曲线;③当两个GNSS水准点间距离接近或小于所有GNSS水准点平均间距时,GNSS水准高程异常对实用地面高程异常的贡献起主要作用;④较大空间尺度的实用地面高程异常精度主要依靠重力地面高程异常控制。 相似文献
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正由于GRACE(gravity recovery and climate experiment)时变重力场模型直接解算质量变化时存在较大的误差,需要对其进行相应的滤波处理,提高质量变化的反演精度。本文总结了GRACE监测全球与区域质量变化的研究进展,分析了最新时变重力场模型的精度及其滤波方法;提出了基于重力位系数协方差阵的时变重力场滤波方法;分析了南极冰盖的质量变化、亚马孙流域陆地水质量和海平面变化。本文的研究成果及创新点主要包括以下几个方面: 相似文献
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Efficient GOCE satellite gravity field recovery based on least-squares using QR decomposition 总被引:3,自引:0,他引:3
We develop and apply an efficient strategy for Earth gravity field recovery from satellite gravity gradiometry data. Our approach
is based upon the Paige-Saunders iterative least-squares method using QR decomposition (LSQR). We modify the original algorithm
for space-geodetic applications: firstly, we investigate how convergence can be accelerated by means of both subspace and
block-diagonal preconditioning. The efficiency of the latter dominates if the design matrix exhibits block-dominant structure.
Secondly, we address Tikhonov-Phillips regularization in general. Thirdly, we demonstrate an effective implementation of the
algorithm in a high-performance computing environment. In this context, an important issue is to avoid the twofold computation
of the design matrix in each iteration. The computational platform is a 64-processor shared-memory supercomputer. The runtime
results prove the successful parallelization of the LSQR solver. The numerical examples are chosen in view of the forthcoming
satellite mission GOCE (Gravity field and steady-state Ocean Circulation Explorer). The closed-loop scenario covers 1 month
of simulated data with 5 s sampling. We focus exclusively on the analysis of radial components of satellite accelerations
and gravity gradients. Our extensions to the basic algorithm enable the method to be competitive with well-established inversion
strategies in satellite geodesy, such as conjugate gradient methods or the brute-force approach. In its current development
stage, the LSQR method appears ready to deal with real-data applications. 相似文献
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The performance of the L-curve criterion and of the generalized cross-validation (GCV) method for the Tikhonov regularization
of the ill-conditioned normal equations associated with the determination of the gravity field from satellite gravity gradiometry
is investigated. Special attention is devoted to the computation of the corner point of the L-curve, to the numerically efficient
computation of the trace term in the GCV target function, and to the choice of the norm of the residuals, which is important
for the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) in the presence of colored observation noise. The
trace term in the GCV target function is estimated using an unbiased minimum-variance stochastic estimator. The performance
analysis is based on a simulation of gravity gradients along a 60-day repeat circular orbit and a gravity field recovery complete
up to degree and order 300. Randomized GCV yields the optimal regularization parameter in all the simulations if the colored
noise is properly taken into account. Moreover, it seems to be quite robust against the choice of the norm of the residuals.
It performs much better than the L-curve criterion, which always yields over-smooth solutions. The numerical costs for randomized
GCV are limited provided that a reasonable first guess of the regularization parameter can be found.
Received: 17 May 2001 / Accepted: 17 January 2002 相似文献
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Space-wise approach to satellite gravity field determination in the presence of coloured noise 总被引:2,自引:2,他引:2
For many years, the gravity field of the Earth was only seen by satellite geodesy as the main factor affecting the orbit and consequently it was retrieved together with a number of other orbital perturbations. Since the advent of a new generation of accelerometers, non-gravitational perturbations can be separated from the gravity effects and a new era of gravity field estimates from space has been born. During preparatory data analysis for new missions performed by the geodetic community, three approaches have been proposed and numerically tested: the brute force method (direct approach), the semi-analytical (time-wise) method and the space-wise method. In particular, the time-wise method takes advantage of the incoming time flow of data and, after performing a Fourier transform of the observation equations, exploits the prevailing block diagonal structure of the normal equations to estimate the spherical harmonic coefficients of the gravity field. Complementary to this is the space-wise approach, which goes back to the traditional computation of the harmonic coefficients by an integration technique or by least-squares collocation. Some advantages and disadvantages are peculiar to both methods, particularly the space-wise approach, which has for a long time ignored the marked signature of the noise spectrum due to the specific measuring conditions of space-borne accelerometers. The application of a proper Wiener filter, exploiting the correlation along the orbit, embedded into an iterative scheme, seems to be the answer. The solution to this major problem of the space-wise approach is illustrated and simulation results are discussed. 相似文献
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不同于当前广泛使用的空域法、时域法、直接解法,本文尝试采用Torus方法处理GOCE实测数据,利用71 d的GOCE卫星引力梯度数据反演了200阶次GOCE地球重力场模型,实现了对参考模型的精化。首先,采用Butterworth零相移滤波方法加移去—恢复技术,处理引力梯度观测值中的有色噪声,并利用泰勒级数展开和Kriging方法对GOCE卫星引力梯度数据进行归算和格网化,计算得到了名义轨道上格网点处的引力梯度数据。然后,利用2D-FFT技术和块对角最小二乘方法处理名义轨道上数据,获得了200阶次的GOCE地球重力场模型GOCE_Torus。利用中国和美国的GPS/水准数据进行外部检核结果说明,GOCE_Torus与ESA发布的同期模型的精度相当;GOCE_Torus模型与200阶次的EGM2008模型相比,在美国区域精度相当,但在中国区域精度提高了4.6 cm,这充分体现了GOCE卫星观测数据对地面重力稀疏区的贡献。Torus方法拥有快速高精度反演卫星重力场模型的优势,可以在重力梯度卫星的设计、误差分析及在轨快速评估等方面得到充分应用。 相似文献
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Gravity field determination from satellite gradiometry 总被引:7,自引:1,他引:7
An orbiting gradiometer measures simultaneously several gravity quantities, ideally all six second-order derivatives of the
gravitational potential. These contain information on the orbit, on the structure of the gravity field, and on the attitude
of the space-craft. Due to the availability of several components simultaneously it is possible to separate orbit determination
from attitude or gravity field recovery. This facilitates the analysis of the gradiometer measurements and allows the use
of the principles of fast spherical harmonic analysis. The separation of gravity field recovery and orbit determination is
tested numerically with a simplified gravity field (with a purely zonal spherical harmonic expansion) up to degree 300. For
both the potential coefficients and for the orbit an almost exact recovery is attained after two iteration steps. 相似文献
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A preliminary error analysis of the gravity field recovery from a lunar Satellite-to-Satellite mission 总被引:2,自引:0,他引:2
Hüseyin Bâki Iz 《Journal of Geodesy》1993,67(3):173-177
Summary A low cost lunar Satellite-to-Satellite radio tracking mission in a low-low configuration could considerably improve the existing knowledge about the lunar gravity field. The impact of various mission parameters that may contribute to the recovery of the gravity field, such as satellite altitude, satellite separation, mission duration, measurement precision and sampling interval were quantified using the Jekeli-Rapp algorithm. Preliminary results indicate that the gravity field resolution up to harmonic degree 40 to 80 is feasible depending on various mission configurations. Radio tracking data from a six-month mission with a precision of 1 mm s–1 every 10 s and 300 km satellite separation at 150 km altitude will permit the determination of 5o×5o mean gravity anomalies with an error of approximately 15 mgals. Consideration of other unaccounted error sources of instrumental, operational as well as environmental nature may lower this resolution. 相似文献
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卫星重力梯度数据重力异常的精度分析 总被引:1,自引:0,他引:1
针对GOCE卫星确定的地球重力场模型精度的不确定性,对比分析GOCE位模型与多个不同重力场模型确定的重力异常,并将其分别与船测重力数据、南极航空重力数据、北极重力数据以及美国和中国台湾地面重力数据比较研究。结果表明:GOCE位模型的内符合精度最高,与地面重力观测数据符合最优;与船测以及航空重力测量符合相对较差、精度较低。研究表明,在一定精度前提下,GOCE卫星确定的重力数据可用于无人区,从而提高重力观测数据的覆盖率。 相似文献
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A geopotential error analysis for a non planar satellite to satellite tracking mission 总被引:1,自引:0,他引:1
This study is concerned with gravity field recovery from low-low satellite to satellite range rate data. Compared against
a coplanar mission an improvement is predicted in errors associated with certain parts of the geopotential by the separation
of the orbital planes of the two satellites. Using Hill's equations an analytical scheme is developed to model the range rate
residuals. It is flexible enough to model the residuals between pairs of satellites in the same orbital plane or whose planes
are separated in right ascension. This scheme should allow the possibility of larger planar separations than previously since
no small angle approximation is made. The effects of such an orientation on gravity field recovery can therefore be analysed
by means of an extensive error analysis. The results of this analysis indicate that a significant improvement in the errors
of the near sectorial coefficients are obtained when the satellite's orbital planes are separated.
Received: 9 April 1996; Accepted: 26 September 1996 相似文献
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利用卫星重力数据计算地幔对流应力场 总被引:1,自引:0,他引:1
针对我国东南边缘及其邻近区域地幔对流应力场分布形态与地表构造活动特征的相关性问题,提出利用Runcorn模型及高阶卫星重力球谐系数计算欧亚板块与菲律宾板块复合接触带及其邻近区域的地幔对流应力场。结果显示,地幔对流应力矢量特征与地震应力场分布具有较好的一致性。在两大板块的接触部位均出现了显著的应力增强与汇聚趋势,同时在琉球海沟的弧后扩张带上出现的较强的地幔对流应力发散带。而在各板块相对稳定的内部区域存在微弱的地幔发散流。通过计算和分析得出,该区域下地壳小尺度的地幔对流可能是控制这一区域型构造过程的重要因素之一。 相似文献