卫星重力测量解析误差分析法

发布时间：2018-03-14 09:04

本文选题：重力测量　切入点：地球重力场　出处：《华中科技大学》2013年博士论文　论文类型：学位论文

【摘要】：卫星重力测量技术被公认为是探测和研究全球重力场最有效且极具发展潜力的方法之一。自进入21世纪以来，基于卫星跟踪卫星技术的CHAMP和GRACE以及基于卫星重力梯度技术的GOCE重力卫星计划相继成功实施，使得人们得以获取高精度和高分辨率的全球重力场信息，进一步提高了对全球物质分布、物质转移交换和地球内部精细结构等科学问题的认识水平。为了研究卫星重力测量计划中指标参数与科学目标之间的关系和评估各种噪声对恢复重力场精度的影响，传统研究方法一般是将重力观测值作为位置或者时间的函数，在此基础上利用最小二乘法进行相关的误差分析。最小二乘误差分析方法从数值的角度间接地进行评估参数的影响，难以直接评估某些单一参数的影响，而且随着解算模型的分辨率越来越高和阶数越来越大，计算量急剧增长并带来严重的数值不稳定性问题。为了快速评估和确定卫星重力测量计划有关参数，，以及评估不同类型载荷噪声的影响，根据仪器功率谱密度和重力位系数阶方差的定义，建立了卫星重力梯度测量噪声与恢复重力场模型精度的直接对应关系。利用二维傅立叶变换性质、二维采样定理和相应的调制理论，进一步推导出了卫星重力测量结果中所含二维空间信号与观测值的一维时间频率的联系，从而可以解析地评估卫星重力测量中色噪声的影响。利用此关系，首先讨论分析了白噪声模型下卫星重力测量技术中测量噪声、卫星轨道高度及运行时间等参数对重力场恢复精度的影响。接着分析了色噪声对恢复重力场模型精度的影响，结果表明低频的噪声在整个频带上都对恢复重力场位系数有影响。考虑到实际测量噪声为色噪声的情况下，如果不采取滤波措施，低频处的1/f噪声将较大地影响恢复重力场的空间分辨率和精度。但是，在使用滤波器后低频噪声得到抑制的同时，重力场信号每一阶所含有的低频信息也被抑制，可能使得单独使用梯度观测值恢复重力场模型系数时产生失真。此外，根据高低卫—卫跟踪测量原理并结合线性扰动理论和控制理论，我们建立起了高低卫—卫跟踪测量噪声功率谱与重力场恢复精度之间的解析表达式，并在此基础上分析讨论了高低卫—卫跟踪中GPS定位误差和静电悬浮加速度计测量噪声对所恢复重力场精度的影响。结果表明目前高低卫—卫跟踪得到的地球重力场精度主要受限于GPS的测量精度。为了获取高精度的月球引力场模型，开展了月球卫星引力梯度测量方案的研究。月球引力梯度测量不仅有利于恢复月球引力场的中短波分量信息，而且还有利于消除探月卫星受到的非保守力的影响，可望利用运行在轨道高度为20km的极圆轨道上、梯度测量水平为30mE/Hz1/2的重力梯度卫星，在半波长为7km的空间分辨率上，确定月球水准面的精度约为20.5cm的月球引力场模型。相对于传统的研究卫星重力测量误差分析和恢复能力论证的方法，我们提出的方法具有简单和直接等优点，且不需要消耗大量计算资源，特别适合项目建议初期对部分观测量或者载荷指标进行快速评估和确定，也可以对卫星重力测量系统数值模拟仿真中参数选择和优化设计提供指导。
[Abstract]:Satellite gravity measurement technology is recognized as one of the detection and study of global gravity field is the most effective and promising method. Since entering since twenty-first Century, based on satellite satellite tracking technology of CHAMP and GRACE and GOCE satellite gravity plan satellite gravity gradient based technology have been successfully implemented, so that people can get high precision and high resolution of the world the gravity field information, to further improve the distribution of the global material, the level of understanding of the mass transfer and exchange of the fine structure of scientific problems. In order to study between the index of satellite gravity measurement plan parameters and scientific objectives and the relationship between the assessment of noise on the recovery effect of gravity accuracy, the traditional research methods are generally gravity observations as the position or function of time, on the basis of using the least squares analysis related least squares error error. Difference analysis method from the numerical point indirectly evaluate parameters of the impact is difficult to directly evaluate certain single parameter, and with the solution model of more and more high resolution and order is more and more big, the sharp increase in the amount of calculation and serious numerical instability problems.
In order to evaluate and determine the parameters of satellite gravity measurement program, and to evaluate the effects of different types of load noise, according to the definition of power spectral density and gravity coefficient variance of order, the establishment of a satellite gravity gradient measurement noise and gravity field recovery model precision direct correspondence. Using two-dimensional Fu Liye transformation properties, two-dimensional sampling theorem and the corresponding modulation theory, deduced the one-dimensional time frequency signal and two-dimensional space observations including satellite gravity measurement results in the value of the link, which can be analytically assess the impact of satellite gravity measurement in noise. Using this relationship, the dissertation analysis the measurement noise of satellite gravity measurement technology white noise model, influence of satellite the orbit height and running time and other parameters on the gravity field recovery precision. Then analyzes the color noise on gravity field recovery model precision The results show that the effect of low frequency noise in the frequency band of gravity field recovery effect coefficient. Taking into account the actual measurement noise is color noise, if you do not take measures to filter, 1/f noise at low frequency will greatly affect the recovery of spatial resolution and accuracy of the gravity field. However, in the use of filter low frequency noise is suppressed at the same time, the low frequency information of each order containing gravity signal is also suppressed, may make use of separate gradient observations of gravity field recovery model coefficients of distortion.
In addition, according to the level of Wei Wei tracking measurement principle and the linear perturbation theory and control theory, we established a low satellite to satellite tracking and noise power spectrum measurement and analytical expression between the precision of gravity field recovery, and on the basis of the discussion of the GPS level of Wei Wei positioning tracking error and accelerometer the effect of measurement noise on the recovery of gravity accuracy. The results show that the measurement accuracy of the low satellite - satellite tracking the earth's gravity field accuracy is mainly limited to GPS.
In order to obtain high precision lunar gravity field model, carried out the research of lunar satellite gravity gradient measurement scheme. The moon's gravity gradient measurement is not only conducive to the recovery of the shortwave component information of lunar gravity field, but also conducive to the elimination of lunar satellite by non conservative force influence, is expected to use in orbit height 20km polar circle track, gradient measurement level of gravity gradient satellite 30mE/Hz1/2, the half wavelength resolution of 7km, determine the lunar geoid accuracy is about lunar gravity field model of the 20.5cm.
Compared with the analysis method of satellite gravity measurement error and traditional recovery ability that our proposed method has the advantages of simple and direct, and does not need to consume a large amount of computing resources, especially for the initial project proposals for fast evaluation and determination of some measurements or load index, can also be on satellite gravity measurement system numerical simulation the parameter selection and optimization design to provide guidance.

【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：P223.4

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