The choice of the spherical radial basis functions in local gravity field modeling   总被引：3，自引：0，他引：3  

R. Tenzer  R. Klees 《Studia Geophysica et Geodaetica》2008,52(3):287-304

The choice of the optimal spherical radial basis function (SRBF) in local gravity field modelling from terrestrial gravity data is investigated. Various types of SRBFs are considered: the point-mass kernel, radial multipoles, Poisson wavelets, and the Poisson kernel. The analytical expressions for the Poisson kernel, the point-mass kernel and the radial multipoles are well known, while for the Poisson wavelet new closed analytical expressions are derived for arbitrary orders using recursions. The performance of each SRBF in local gravity field modelling is analyzed using real data. A penalized least-squares technique is applied to estimate the gravity field parameters. As follows from the analysis, almost the same accuracy of gravity field modelling can be achieved for different types of the SRBFs, provided that the depth of the SRBFs is chosen properly. Generalized cross validation is shown to be a suitable technique for the choice of the depth. As a good alternative to generalized cross validation, we propose the minimization of the RMS differences between predicted and observed values at a set of control points. The optimal regularization parameter is determined using variance component estimation techniques. The relation between the depth and the correlation length of the SRBFs is established. It is shown that the optimal depth depends on the type of the SRBF. However, the gravity field solution does not change significantly if the depth is changed by several km. The size of the data area (which is always larger than the target area) depends on the type of the SRBF. The point-mass kernel requires the largest data area.  相似文献   

华南地区地壳厚度变化及对成矿类型的制约:来自卫星重力数据的约束          下载免费PDF全文

罗凡  严加永  付光明  王昊  陶鑫  罗磊 《中国地质》2019,46(4):759-774

华南地区是中国金属矿产资源的“大粮仓”,分布有多个多金属成矿带。多金属成矿带的形成常伴随着地下特殊的深部背景和过程,通过莫霍面深度的计算,对华南地区的地壳厚薄变化所反映的壳幔耦合关系进行研究,可为探索华南地区地下巨量金属资源的形成与演变过程提供参考。本文首先基于球坐标的重力解算方法对高阶卫星重力场模型EIGEN-6C4的数据进行校正,得到华南地区的卫星布格重力异常。然后采用改进的Parker-Oldenburg方法进行变密度界面反演,获得华南地区莫霍面起伏特征。最后结合区内不同成矿带的范围和前人发表的地质、地球化学等资料,探讨华南地区不同成矿带的成矿物质来源与莫霍面起伏的关系。认为长江中下游和钦杭东段处于莫霍面隆起区域的成矿带,幔源物质对其成矿作用起主导地位,形成以铜、铁为主的多金属矿床;南岭、武夷、钦杭西段及鄂西—湘西位于莫霍面隆-陷交替区域的成矿带,成矿与壳、幔源物质的相互作用密切相关,最终形成钨、锡、金、银、铅锌等多金属矿床。  相似文献   

基于球面波势函数基本解方法的弹性波三维散射与动应力求解     

刘中宪  王治坤  梁建文  王楚楚 《岩土力学》2019,(7):2730-2738

针对弹性波三维散射和动应力集中问题,提出一种基于球面波势函数的基本解方法(SWP-MFS)。方法基于单层位势理论,采用膨胀波和矢量剪切波球面波势函数构造散射波场,根据边界条件建立边界积分方程并配点求解。精度检验表明,该方法具有良好的数值精度及稳定性。以无限空间中三维夹杂体及空洞对平面P、SV波的散射为例,进行方法展示,并揭示了三维夹杂体周围弹性波散射的一些重要规律。结果表明:三维夹杂体随其内部介质刚度降低,位移谱曲线震荡越加强烈。三维球形空洞在P波和SV波水平入射下应力集中规律不同,前者在顶部和底部及附近更明显,后者在纵截面两45°角线附近更明显。与以往的集中力源函数相比,新的波场构造基本解更为简洁易用,为三维弹性波动分析提供了一种新型无网格数值方法。  相似文献   

变差函数中加权系数拟合方法的改善          下载免费PDF全文

程勖  杨毅恒 《地球物理学进展》2009,24(1):362-366

变差函数拟合效果的优劣是提高求解变差函数精度的关键步骤,结合加权多项式法和线性规划法的优点,提出使用处理滞后距的方法得到权系数的线性规划法进行球状模型的参数估计,对新疆贝克滩水系沉积物化探数据进行空间分析,结果表明:预测值与样品实测值误差较小,提高预测值的精度.  相似文献   

球体位错理论的基本解     

周新  孙文科 《大地测量与地球动力学》2017,37(11):1105-1111

位错理论是现代地震学中计算地球内部位错源引起的地表变形的重要理论模型。诸多学者对准静态位错理论模型进行了研究,其中大量工作是在前人给出的基本解的基础上进行的。回顾了位错理论模型的基本物理方程,包括平衡方程、本构关系和泊松方程,并分别推导了无自重、不可压缩、自重可压缩的地球模型下的通解。给出的基本解可以用于进一步理解和计算一维径向分层的地震变形问题。  相似文献   

粘弹性准饱和土中球空腔的动力响应   总被引：2，自引：0，他引：2  

徐长节  马晓华 《岩土力学》2005,26(8):1189-1194

从工程实际出发,采用粘弹性两相介质模型,考虑土骨架的粘性以及流体与固体之间的耦合作用,利用Laplace变换求解了粘弹性准饱和土中球空腔的动力响应问题,得到了变换域内的解析解。借助数值Laplace反变换,数值分析了粘弹性准饱和土中球空腔动力响应的位移、应力及孔压的变化规律。为分析地下结构动力响应提供了一种有效的方法,模型符合工程实际,有一定的工程应用价值。  相似文献   

Spherical gauges for improving the accuracy of rainfall measurements     

Mingteh Chang  Lee A. Flannery 《水文研究》2001,15(4):643-654

Rain‐gauge catch efficiencies are affected by wind. Wind makes raindrops fall at an angle of inclination and the effective diameter of the rain gauge orifice smaller than if raindrops fall into the gauge vertically. Two spherical and two semi‐spherical orifices were designed to modify standard gauges and others in use today. The two spherical orifices catch rain with an effective diameter always equal to the actual diameter regardless of wind speed and direction. The semi‐spherical orifices, used side‐by‐side with a standard gauge, correct 50% of catch deficiencies made by the standard gauge. Tests based on 115 storms show that the four new gauges caught more rainfall than the standard gauge, with an average catch increase ranging from 8% to 16%. Compared with the pit gauge, average deficiency in catch ranged from ?1% (spherical rain gauge orifice with cylinders) to 4%, whereas the deficiency for the standard gauge was ?10%. Percentage deficiencies of the new gauges were positively affected by wind speed, raindrop inclination and rainfall intensity. Although the new gauges tended to underestimate the standard gauge in small storms (<0·25 cm) and overestimated the pit gauge under strong winds, their deviations are small. Underestimates for small storms could be improved by using gauge materials that reduce surface temperature, evaporation and water retention. The gauges are simple in design, easy to operate and inexpensive. In order to maintain a historically consistent set of rainfall data, a dual‐gauge (standard gauge + spherical gauge) is recommended for existing rainfall stations. The new rain gauge orifices are suitable for large‐scale applications. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Spherical harmonic analysis of the CRUST 2.0 global crustal model     

D. Tsoulis 《Journal of Geodesy》2004,78(1-2):7-11

The spherical harmonic analysis of the 2×2 density and stratification information contained in the global crustal model CRUST 2.0 is presented from the viewpoint of gravity field recovery and interpretation. Using a standard Airy/Heiskanen (A/H) isostatic hypothesis and a radially distributed compensation mechanism, two models of topographic/isostatic (t/i) potential harmonic coefficients are obtained up to degree and order 90. The CRUST-derived coefficients are compared with the spectrum of uncompensated topography, with the EGM96 observed gravity field, and with the t/i spectrum based on an A/H hypothesis with a constant compensation depth of 30 km. The signal degree variances of both CRUST models decrease quite smoothly towards degree 90, while the seven-layer model approaches the EGM96 spectrum for degrees 80–90. The significant deviation of the CRUST spectra from the A/H combined spectrum may prove of relevance to local and regional applications investigating the validity of current isostatic hypotheses.Acknowledgments. Sincere thanks go to Nikolaos Pavlis and three unknown referees for their thoughtful comments. Figure 1 has been produced using the mapping package m_map by R. Pawlowicz, which is a MATLAB toolbox that can be freely downloaded from http://www2.ocgy.ubc.ca/~rich/map.html  相似文献   

Derivations of the equation for the field lines of an axisymmetric multipole     

Bertha Jeffreys 《Geophysical Journal International》1988,92(2):355-356

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位移矢量的矢量球函数表达     

高锡铭 《大地测量与地球动力学》1994,(3)

本文给出了位移矢量的矢量球函数表达及其有关的公式。使用这种表达对球形形变问题，无论是理论研究还是实际计算，都会起到重要的作用，并且十分方便。  相似文献