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The GPS-gravimetry boundary value problem

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Science China Earth sciences 2005年第3期48卷 398-405页

作者： YU Jinhai1.2.& ZHANG Chuanding2.1. institute of geodesy and Geophysics of{2., wuhan 430077, China 2. Zhengzhou Information Engineering University, Zhengzhou 450052. China 1. institute of {1. and Geophysics of{2. 430077 Wuhan China 2. Zhengzhou Information Engineering University 450052 Zhengzhou China

How to determine the earth’s external gravity field with the accuracy of O(T2. by making use of GPS data and gravity values measured on the earth’s surface is dealt with in this paper. There are two main steps: to extend these measured values on the earth’s surface onto the reference ellipsoid at first and then to seek for the integral solution of the external Neumann problem outside the ellipsoid. In addition, the corresponding judging criteria of accuracy to solve the GPS-gravity boundary value problem are established. The integral solution given in the paper not only contains all frequency-spectral information of the gravity field with the accuracy of O(T 2., but is also easily computed. In fact, the solution has great significance for both theory and prac- tice.

关键词： Neumann boundary value problem, integral solution, gravity disturbance.

Analysis and application of automatic deformation monitoring data for buildings and structures of mining area

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中国有色金属学会会刊：英文版 2011年第S3期21卷 516-522页

作者： XIAO Jie1. 2. 3, ZHANG Jin4 1. {1. of geodesy and Geophysics,{2., wuhan 430077, China 2. Key Laboratory of Dynamic geodesy, {1. of geodesy and Geophysics,{2., wuhan 430077, China 3. Graduate School of{2., Beijing 1.0049, China 4. Department of Surveying and Mapping, Taiyuan University of Technology, Taiyuan 03002., China Taiyuan Univ Technol Dept Surveying & Mapping Taiyuan 030024 Peoples R China chinese Acad Sci Inst Geodesy & Geophys Key Lab Dynam Geodesy Wuhan 430077 Peoples R China chinese Acad Sci Grad Sch Beijing 100049 Peoples R China

The buildings and structures of mines were monitored automatically using modern surveying technology. Through the analysis of the monitoring data, the deformation characteristics were found out from three aspects containing points, lines and regions, which play an important role in understanding the stable state of buildings and structures. The stability and deformation of monitoring points were analysed, and time-series data of monitoring points were denoised with wavelet analysis and Kalman filtering, and exponent function and periodic function were used to get the ideal deformation trend model of monitoring points. Through calculating the monitoring data obtained, analyzing the deformation trend, and cognizing the deformation regularity, it can better service mine safety production and decision-making.

关键词： wavelet analysis Kalman filtering deformation monitoring data analysis mine

General inverse of Stokes, Vening-Meinesz and Molodensky formulae

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Science China Earth sciences 2006年第5期49卷 499-504页

作者： CHENG Luying1.2.& XU Houze1.1. {1. of geodesy and Geophysics,{2., wuhan 430077, China 2. Xi’an Research {1. of Surveying and Mapping, Xi’an 71.054, China 1. institute of {1. and Geophysics Chinese Academy of Sciences Wuhan 430077 China 2. Xi’an Research {1. of Surveying and Mapping Xi’an 710054 China

The operator operations between the disturbing potential and the geoidal undulation, the gravity anomaly, the deflection of the vertical are defined based on the relations among the gravity potential, the normal gravity potential and the disturbing potential. With the sphere as the boundary surface, based on the solution of the external boundary value problem for the disturbing potential by the spherical harmonics in the physical geodesy, the general inverse Stokes’ formula, the general inverse Vening-Meinesz formula and the general Molodensky’s formula are derived from the operator operations defined. The general formulae can get rid of the restriction of the classical formulae only used on the geoid. If the boundary surface is defined as the geoid, the general formulas are degen- erated into the classic ones.

关键词： spherical harmonics, boundary value problem, general inverse Stokes' formula, general inverse Vening-Meinesz formula, general Molodensky's formula.

Spectral analysis of quasi-stationary sea surface topography from GRACE mission

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Science China Earth sciences 2005年第11期48卷 2040-2048页

作者： ZHANG Zizhan1.2.& LU Yang1.3 1. {1. of geodesy and Geophysics,{2., wuhan 430077, China 2. Graduate School of the{2., Beijing 1.0039, China 3. Unite Center for Astro-geodymics Research,{2., Shanghai 2.0030, China 1. institute of {1. and Geophysics Chinese Academy of Sciences 430077 Wuhan China 2. Graduate School of the{1. 100039 Beijing China 3. Unite Center for Astro-geodymics Research Chinese Academy of Sciences 200030 Shanghai China

During the last two decades satellite altimetry has offered an abundance of meas-urements of the sea surface resulting in the improvement of global mean sea surface height (MSSH) and marine geoid determination. On the other hand, with the launching of new genera-tion gravity satellites, some high accuracy long-wavelength gravity models are available. These breakthroughs give us a great opportunity for new estimation of quasi-stationary sea surface topography (QSST). In this paper, the new gravity model GGM01. derived from GRACE mission is briefly presented, and a new global high precision and high-resolution QSST is determined based on the GGM01. model and the global MSSH. The spectral features of the QSST esti-mated by GGM01. and EGM96 gravity model to degree/order 2.0 are discussed by spectral analysis. As a result, the QSST is mainly composed of long waves, medium waves partially and short waves scarcely, its power spectral structures are different between the zonal direction and the meridional direction, there are great differences between the two models, which maybe ex-plain why the ocean currents derived from the two gravity models by Tapley show different pat-terns.

关键词： quasi-stationary sea surface topography, mean sea surface height, GGM01. fast Fourier transform, spectral analysis

Validating global hydrological models by ground and space gravimetry

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chinese Science Bulletin 2009年第9期54卷 1534-1542页

作者： ZHOU JiangCun1.2.3, SUN HePing1.2.& XU JianQiao1.2.1.institute of geodesy and Geophysics,{2., wuhan 430077, China 2.Key Laboratory of dynamic geodesy,{2., wuhan 430077, China 3 Graduate University of{2., Beijing 1.0049, China institute of {1. and Geophysics Chinese Academy of Sciences Wuhan 430077 China Key Laboratory of dynamic geodesy Chinese Academy of Sciences Wuhan 430077 China Graduate University of chinese academy of sciences Beijing 100049 China

The long-term continuous gravity observations obtained by the superconducting gravimeters (SG) at seven globally-distributed stations are comprehensively analyzed. After removing the signals related to the Earth's tides and variations in the Earth's rotation, the gravity residuals are used to describe the seasonal fluctuations in gravity field. Meanwhile, the gravity changes due to the air pressure loading are theoretically modeled from the measurements of the local air pressure, and those due to land water and nontidal ocean loading are also calculated according to the corresponding numerical models. The numerical results show that the gravity changes due to both the air pressure and land water loading are as large as 1.0×1.-9 m s-2.in magnitude, and about 1.×1.-9 m s-2.for those due to the nontidal ocean loading in the coastal area. On the other hand, the monthly-averaged gravity variations over the area surrounding the stations are derived from the spherical harmonic coefficients of the GRACE-recovered gravity fields, by using Gaussian smoothing technique in which the radius is set to be 600 km. Com-pared the land water induced gravity variations, the SG observations after removal of tides, polar mo-tion effects, air pressure and nontidal ocean loading effects and the GRACE-derived gravity variations with each other, it is inferred that both the ground- and space-based gravity observations can effec-tively detect the seasonal gravity variations with a magnitude of 1.0×1.-9 m s-2.induced by the land water loading. This implies that high precision gravimetry is an effective technique to validate the re-liabilities of the hydrological models.

关键词：重力测量水文模型模型验证和空间地面重力变化季节性波动空气压力

Atmospheric gravity Green's functions

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chinese Science Bulletin 1997年第20期42卷 1712-1719页

作者： SUN HepingLaboratory of Dynamic geodesy, {1. of geodesy and Geophysics, chinese academy of sciences, wuhan 430077, China Laboratory of Dynamic geodesy Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan China

THE observational accuracy of the superconducting gravimeter has now reached 0.1.μGal levelor better, with characteristics of the low noise, high sensitivity and better continuity and sta-bility. It will play an important part in the study of the change in (non-) tidal gravity signals,especially in the application of the geophysics and geodynamics. However, the instrument

关键词： air pressure Green’s functions atmospheric gravity admittance.

Variation properties of ionospheric eclipse factor and ionospheric influence factor

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Progress in Natural Science:Materials International 2005年第6期15卷 573-576页

作者： ZHAO Chunmei 1.2.*, YUAN Yunbin1. OU Jikun1.and CHEN Jinping3(1. {1. of geodesy and Geophysics,{2., wuhan 430077, China 2. Graduate School of{2., Beijing 1.0039, China 3. Department of Precision Instrument and Mechanology, Tsinghua University, Beijing 1.0084, China) institute of {1. and Geophysics Chinese Academy of Sciences Wuhan 430077 China Graduate School of chinese academy of sciences Beijing 100039 China Department of Precision Instrument and Mechanology Tsinghua University Beijing 100084 China

The concepts and calculation methods of ionospheric eclipse factor (IEF) and ionospheric influence factor (IFF) are further illustrated. The temporal and spacial variation properties of IEF and IFF are studied, which shows that the properties are influenced by the geographic position and season. The possibility of improving the precision of using GPS data to determine ionospheric delay based on the above variation properties is also analysed.

关键词： GPS ionospheric eclipse factor ionospheric influence factor

Determination of vertical gradient of gravity anomaly with topographic data

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chinese Science Bulletin 1999年第11期44卷 1029-1034页

作者： ZHANG Chijuninstitute of {1. and Geophysics ,{2. , wuhan 430077 , China institute of {1. and Geophysics Chinese Academy of Sciences Wuhan China

The role of vertical gradient of gravity anomaly in the solution and interpretation of geological and geophysical problems on superficial layer is increasingly evident. However, it is difficult to directly observe the vertical gradient of gravity anomaly in mountainous area. Moreover,aerial and satellite gravity gradient measurments have not been put into practice up to date *** vertical gradient of gravity anomaly is calculated by use of topographic data and several problems concerned are investigated and discussed. It turns out in theory and practice that the relative error of the vertical gradient determined with the method is only 5%, and when the vertical gradient of gravity anomaly reaches the maximum 1.000 ns-2./sup> the error is only 50 ns-2./sup>. In addition, how to divide ring zones in calculation and the errors caused by the inaccuracy of landform elevation and rock density has been quantitatively analysed.

关键词： vertical gradient gravity anomaly topographic mass geoid.

Separation of systematic errors in processing high precision GPS baselines

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中国有色金属学会会刊：英文版 2005年第S1期15卷 139-141页

作者： WANG Zhen-jie~(1. 2., QU Guo-qing~2.(1. institute of Architectural Engineering, Shangdong University of Technology, Zibo 2.501.0} China 2. institute of {2. and Geophysics, chinese academy of sciences, wuhan 430077,China) Shandong Univ Technol Inst Architectural Engn Zibo 255012 Peoples R China chinese Acad Sci Inst Geodesy & Geophys Wuhan 430077 Peoples R China

The research is based on the double difference observations and semi-parametric model. Systematic errors are considered as the parameters to be estimated, and brought into the GPS observation equations. High precision baselines are obtained after separating systematic errors. The crucial steps are choosing regularizer and regularization parameters in processing GPS systematic errors by using the semi-parametric model. We propose a new regularizer and apply it to dealing with systematic errors. Also, we compare it with one proposed by other researchers. This comparison is done when all the regularization parameters equal to one. The computation result of the example shows that two regularizers correspond well and they can separate systematic errors successfully. Thus, we can get high precision baselines. Compared with R=QK-1.′, our regularizer R=GTG is simple, so, the process of resolving the high precision baselines is relatively simple.

关键词： GPS systematic errors semi-parametric model regularizer