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101.
J. Klokoník J. Kostelecký C.A. Wagner P. Schwintzer Ch. Förste R. Scharroo 《Journal of Geodesy》2005,78(7-8):405-417
Since the advent of CHAMP, the first in a series of low-altitude satellites being almost continuously and precisely tracked by GPS, a new generation of long-wavelength gravitational geopotential models can be derived. The accuracy evaluation of these models depends to a large extent on the comparison with external data of comparable quality. Here, two CHAMP-derived models, EIGEN-1S and EIGEN-2, are tested with independent long-term-averaged single satellite crossover (SSC) sea heights from three altimetric satellites (ERS-1, ERS-2 and Geosat). The analyses show that long-term averages of crossover residuals still are powerful data to test CHAMP gravity field models. The new models are tested in the spatial domain with the aid of ERS-1/-2 and Geosat SSCs, and in the spectral domain with latitude-lumped coefficient (LLC) corrections derived from the SSCs. The LLC corrections allow a representation of the satellite-orbit-specific error spectra per order of the models spherical harmonic coefficients. These observed LLC corrections are compared to the LLC projections from the models variance–covariance matrix. The excessively large LLC errors at order 2 found in the case of EIGEN-2 with the ERS data are discussed. The degree-dependent scaling factors for the variance-covariance matrices of EIGEN-1S and –2, applied to obtain more realistic error estimates of the solved-for coefficients, are compatible with the results found here. 相似文献
102.
Li Chao 《Mathematical Geology》1998,30(1):43-56
A multidimensional version of the time varying periodogram has been developed. The estimation method based on the multidimensional time-varying periodogram has been applied to a nonstationary multidimensional storm model. This work proposes that the multidimensional time varying periodogram is capable of estimating nonstationary spectral density functions in space and time. 相似文献
103.
104.
Abstract: Low sulphidation epithermal Au-Ag deposits constitute a major exploration target for many mining companies worldwide. These deposits are commonly characterized by quartz vein systems which formed at temperatures often in the range 150–250°C giving rise to major alteration halos. Accompanying mineralization and associated alteration is the destruction and redistribution of magnetite in the host rocks and the formation of various K-bearing minerals such as adularia, illite and alunite. These alteration halos can often cover an area of at least several square kilometres and as such have the potential to be detected during reconnaissance geological surveys utilizing high resolution airborne aeromagnetic and radiometric sensors.
Analysis of airborne magnetic and radiometric data recently acquired over the Hokusatsu Region of SW Kyushu indicates that major low sulphidation epithermal Au-Ag deposits are characterized by several distinct geophysical features varying with the degree of post-mineralization cover and level of erosion. Several deposits coincide with extensive magnetic "flat" and high radiometric K–counts. In addition, several workers have shown that a very close association exists between Bouguer gravity highs and epithermal Au mineralization in the Hokusatsu Region. The combined use of areomagnetics, radiometrics and gravity data therefore provides an exceptionally effective approach to exploration for low sulphidation epithermal Au–Ag deposits in the Hokusatsu Region of Japan. 相似文献
Analysis of airborne magnetic and radiometric data recently acquired over the Hokusatsu Region of SW Kyushu indicates that major low sulphidation epithermal Au-Ag deposits are characterized by several distinct geophysical features varying with the degree of post-mineralization cover and level of erosion. Several deposits coincide with extensive magnetic "flat" and high radiometric K–counts. In addition, several workers have shown that a very close association exists between Bouguer gravity highs and epithermal Au mineralization in the Hokusatsu Region. The combined use of areomagnetics, radiometrics and gravity data therefore provides an exceptionally effective approach to exploration for low sulphidation epithermal Au–Ag deposits in the Hokusatsu Region of Japan. 相似文献
105.
In Part I we focussed on a convergent representation of the gravitational potential generated bytopographic masses on top of the equipotential surface atMean Sea Level, thegeoid, and by those masses which compensate topography. Topographic masses have also been condensated, namely represented by a single layer. Part II extends the computation of the gravitational field of topographic-isostatic masses by a detailed analysis of itsforce field in terms ofvector-spherical harmonic functions. In addition, the discontinuous mass-condensated topographic gravitational force vector (head force) is given. Once we identify theMoho discontinuity asone interface of isostatically compensated topographical masses, we have computed the topographic potential and the gravitational potential which is generated by isostatically compensated masses atMean Sea Level, the geoid, and illustrated by various figures of geoidal undulations. In comparison to a data oriented global geoid computation ofJ. Engels (1991) the conclusion can be made that the assumption of aconstant crustal mass density, the basic condition for isostatic modeling, does not apply. Insteaddensity variations in the crust, e.g. betweenoceanic and continental crust densities, have to be introduced in order to match the global real geoid and its topographic-isostatic model. The performed analysis documents that thestandard isostatic models based upon aconstant crustal density areunreal. 相似文献
106.
地面锋附近重力流的产生及其锋生作用 总被引:3,自引:0,他引:3
本文用旋转大气的两维非静力模型,用Simpson和Linden[1]的级数展开方法和数值积分方法讨论了地面锋附近由于非地转平衡所产生的重力流及锋生作用。 相似文献
107.
A. H. W. Kearsley R. Forsberg A. Olesen L. Bastos K. Hehl U. Meyer A. Gidskehaug 《Journal of Geodesy》1998,72(10):600-605
Two detailed geoids have been computed in the region of North Jutland. The first computation used marine data in the offshore
areas. For the second computation the marine data set was replaced by the sparser airborne gravity data resulting from the
AGMASCO campaign of September 1996. The results of comparisons of the geoid heights at on-shore geometric control showed that
the geoid heights computed from the airborne gravity data matched in precision those computed using the marine data, supporting
the view that airborne techniques have enormous potential for mapping those unsurveyed areas between the land-based data and
the off-shore marine or altimetrically derived data.
Received: 7 July 1997 / Accepted: 22 April 1998 相似文献
108.
华北强震地形变及重力前兆特征与孕震机理 总被引:6,自引:0,他引:6
通过分析华北地区强震地形变及重务前兆特征,发现震前在较大范围内存在与构造密切相关的动力不过程;在震中区介质状态发生变化。在此基础上提出了改进的组合-硬化模式:调整单元的运动,牵动较大范围构造运动的加及断层两侧深层介质密度变化;应力集中单元由于能量的不断积累,介质出现硬化过程。上述机理形成了前兆的各个阶段。 相似文献
109.
110.
利用地震面波和重力资料联合反演地壳—上地幔三维密度结构的方法探讨 总被引:2,自引:0,他引:2
本文探讨了利用地震面波和重力资料联合反演地壳-地幔三维密度结构的反演问题。首先建立了地震面波和重力资料的观测方程,然后应用广义线性反线理论给出了反演问题的解。模型试验结果表明,与单纯面波反演的结果相比,联合反演的解在分析率和方差两个方面都有改善,当加入扰动重力数据时,在0-300km深度范围内联合反演的结果明显好于单纯面波反演的结果。 相似文献