GOCE重力场模型的精度评估     

赵德军  徐新强  陈永祥  李帅鑫 《大地测量与地球动力学》2015,35(2):322-325

从累积大地水准面误差、几何水准面与重力水准面之差、不同频段重力场模型的组合3个方面,评估了欧空局发布的时域法、空域法、直接法3个模型的精度。频谱分析和北美实测GPS/水准结果表明,第4代直接法模型精度达到“空间分辨率100 km情况下,大地水准面精度±1 cm”的设计要求|直接法模型精度高于时域法模型和空域法模型|GOCE数据能有效地提高重力场中频、甚至高频信号的精度。  相似文献   

Density modeling of the Escollos Alijos Seamount from inversion of its geoid undulation anomaly     

《Geofísica Internacional》2014,53(3):333-341

Escollos Alijos is a large seamount located in the NE Pacific Ocean about 300 km off the Baja California Peninsula. Geochronology and geochemical analysis of volcanic rocks capping the seamount indicate recent magmatism that resulted from extensive differentiation of a mildly alkalic basalt parent magma.Escollos Alijos is located towards the eastern edge of a long-wavelength geoid undulation minimum, of up to -47 m with respect of the WGS84 ellipsoid, which extends over the northeastern Pacific Ocean. Subtracting from the geoid undulation its long-wavelength component and the undulation due to the seamount topography itself, a negative undulation anomaly persists that indicates a mass deficit at depth. Linear inversion of the undulation anomaly yields a region characterized by a negative density contrast, localized under the seamount at a depth between 9 and 13 km.The age and chemical composition of Escollos Alijos, and the inferred mass deficit suggest magma trapped between the oceanic crust and the uppermost mantle, which explains the magmatic activity in recent times.  相似文献   

From Discrete Gravity Survey Data to a High-resolution Gravity Field Representation in the Nordic-Baltic Region     

Silja Märdla  Jonas Ågren  Gabriel Strykowski  Tõnis Oja  Artu Ellmann  René Forsberg 《Marine Geodesy》2017,40(6):416-453

The deduction of a regularly spaced gravity anomaly grid from scattered survey data is studied, addressing mainly two aspects: reduction of gravity to anomalies and subsequent interpolation by various methods. The problem is illustrated in a heterogeneous study area and contrasting test areas including mountains, low terrains, and a marine area. Provided with realistic error estimates, Least Squares Collocation interpolation of Residual Terrain Model anomalies yields the highest quality gravity grid. In most cases, the Bouguer reduction and other interpolation methods tested are equally viable. However, spline-based interpolation should be avoided in marine areas with trackwise survey data.  相似文献   

Comparison of geosat and gravimetric geoid profiles in the North Sea     

Michael P. Stewart  Will E. Featherstone  Jonathan F. Kirby  Mark Dumville 《Marine Geodesy》2013,36(4):319-330

Sea surface height profiles derived from 2‐year, repeat track, Geosat altimeter data have been compared with a regional gravimetric geoid in the western North Sea, computed using a geopotential model and terrestrial gravity data. The comparison encompasses 18 Geosat profiles covering a 750 × 850 km area of the North Sea. After a second‐order polynomial was used to model the long‐wavelength differences which cannot be clearly separated over an area of this size, results show agreement to better than ±3 cm for wavelengths between approximately 20 and 750 km. In regions where terrestrial gravity data were not available to improve the geoid, similar comparisons with the OSU91A geopotential model alone show differences of up to ±6 cm. This illustrates the importance of incorporating local gravity data in regional geoid computations, and partly validates the regional gravimetric geoid solution and Geosat sea surface profiles in the western North Sea. It is concluded that, in marine areas where the sea surface topography is known to be small in magnitude, Geosat sea surface profiles can act as an independent control on gravimetric geoids in the medium‐wavelength range.  相似文献   

Improvement in the Determination of the Marine Geoid by Estimating the Bathymetry from Altimetry and Depth Soundings     

GEORGIOS S. VERGOS  MICHAEL G. SIDERIS 《Marine Geodesy》2013,36(1):81-102

Abstract

The contribution of bathymetry to the estimation of gravity field related quantities is investigated in an extended test area in the Mediterranean Sea. The region is located southwest of the island of Crete, Greece, bounded between 33^? ≤ ? ≤ 35^? and 15^? ≤ λ ≤ 25^?. Gravity anomalies from the KMS99 gravity field and shipborne depth soundings are used with a priori statistical characteristics of depths in a least-squares collocation procedure to estimate a new bathymetry model. Two different global bathymetry models, namely JGP95E and Sandwell and Smith V8, are used to derive the depth a priori statistical information, while the estimated model is compared against both the global ones and the shipborne depth soundings to assess whether there is an improvement. Various marine geoid models are estimated using ERS1 and GEOSAT Geodetic Mission altimetry and shipborne gravity data. In that process, the effect of the bathymetry is computed using both the estimated and the original depths through a residual terrain modeling reduction. The TOPEX/Poseidon Sea Surface Heights, known for their high accuracy and precision, and the GEOMED solution for the geoid in the Mediterranean are used as control for the validation of the new geoid models and to assess the improvement that the estimated depths offer to geoid modeling. The results show that the newly estimated bathymetry agrees better (by about 30 to 300 m) with the shipborne depth soundings and provides smoother residual geoid heights and gravity anomalies (by about 8–20%) than those from global models. Finally, the achieved accuracy in geoid modeling ranges between 6 and 10 cm (1σ).  相似文献   

论确定全球大地水准面的斯托克斯方法     

申文斌 《测绘学报》2012,41(5):670-675

确定全球大地水准面最常用的方法是斯托克司方法。然而,除了人们熟知的缺陷之外,斯托克司方法还存在人们没有意识到的理论困难：当大地水准面位于参考椭球（WGS84椭球）内部时,在大地水准面上及其与参考椭球面界定的区域中扰动位没有定义,当然在这部分区域也不调和。为了解决这一困难,可以选取一个包含在大地水准面内部的由四个基本参数唯一确定其外部正常重力位的参考椭球（简称内部椭球）,其中心与 WGS84 椭球的中心重合,其中的两个基本参数,旋转角速度和地心引力常数,与 WGS84 椭球面的相同,另外两个参数,半长轴和扁率,如此选取,使得内部椭球产生的新的正常重力位在 WGS84 椭球面上与大地水准面上的重力位 相等。这样,传统的斯托克司方法中存在的理论困难不复存在。  相似文献   

两种改进Stokes函数在中国近海大地水准面中的应用     

褚永海  李建成  晁定波  傅露 《武汉大学学报(信息科学版)》2012,37(10):1160-1163

基于移去计算恢复技术(RCR),结合中国近海区域Sandwell测高重力数据,分析了VK和FEO核函数不同阶数条件下,球冠半径大小对残余大地水准面结果的影响。结果表明,在本测试区域,当核函数阶数较大时(P=L=90和P=L=120),球冠半径的增加对残余大地水准面的影响不显著。综合低阶核函数和较高阶核函数的计算结果,球冠半径为3°是一个较优参数。利用GPS水准数据对计算结果进行检核表明,采用改进的椭球核函数比球面核函数计算精度可以提高1.5cm。  相似文献   

GPS水准面拟合方法研究   总被引：8，自引：0，他引：8  

姚吉利  褚丽丽  于志路 《测绘工程》2005,14(4):23-26

研究用较多已测点的原始数据,分别采用GPS水准的六参数法、多面函数法、移动曲面拟合法、有限元法逼近GPS网中较少检核点的高程异常值;再用较少已测点的原始数据,逼近GPS水准网中较多检核点的高程异常值.通过对实测数据的计算分析可发现,具有分区拟合性质的移动曲面拟合法与有限元法较优,使用较少的拟合点时,实测三等水准联合GPS高程观测可取代四等水准测量.  相似文献   

区域性大地水准面的确定   总被引：8，自引：1，他引：7  

黄志洲  钟金宁  周卫  崔立新 《测绘科学》2004,29(2):16-18

精确求定区域性大地水准面是大地测量学的一项重要科学目标 ,也是一项极具实用价值的工程项目。本文以某地区为例 ,描述区域性大地水准面确定的基本方法、一般过程和步骤  相似文献   

Topography and geoid anomalies due to density heterogeneities at the base of the thermal lithosphere: application to oceanic swells and small-wavelength geoid lineations     

L. Fleitout  C. Moriceau 《Geophysical Journal International》1991,107(2):265-277

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