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重力梯度张量是重力位二阶导,相比重力异常能够更好反映局部区域的细节特征。因此重力梯度导航理论上能为惯性导航提供更好的辅助。重力梯度导航的关键技术之一是背景基准图的构建,推导了扰动重力梯度张量与扰动位在局部指北坐标系中的关系式,并基于EGM2008地球重力场模型构建了一块范围的海域扰动重力梯度张量基准图。为了快速构建基准图,选取了合适的勒让德函数,并将每一个梯度张量的计算式改变求和顺序来提高同一纬度圈上的计算点的计算速度。最后利用梯度张量对角线上三元素满足拉普拉斯约束条件的原理验证了所得基准图的正确性。 相似文献
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全球重力场模型是当今物理大地测量学最为活跃的研究领域之一。本文基于目前国内外最新的重力场模型理论研究成果,提出了利用中国地区细部数据和全球卫星测高2’×2’网格重力异常扩展超高阶位模型的计算方法,详细讨论了数值解算过程中的稳定性和可靠性问题。以EGM96和GPM98CR模型作为参考模型,在全球意义上分别解算得到MOD99a(360阶)、MOD99b(720阶)和MOD99c/d(1800阶),将系列模型MOD99a/b/c/d同中国地区72个GPS水准大地水准面和全球海洋12个地区的卫星测高大地水准面进行了比较,并通过功率谱分析方法检验了4组模型的有效性和可靠性。 相似文献
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基于106个月的Grace(gravity recovery and climate experiment)月重力场模型(120阶次),消除了月重力场的月、季度及年度变化,得到了稳态的地球重力场模型(Grace_sta)。在2~120阶次之间,Grace_sta与已有高阶重力场EGM2008及EGM96三个模型的阶方差是一致的。在2~100阶次之间,Grace_sta模型误差阶方差要小于EGM2008与EGM96误差阶方差。在全球范围内,Grace_sta重力场的大地水准面与EGM2008相应阶次的大地水准面标准差约为3cm,与EGM96模型大地水准面差异则高达52cm。结果表明,Grace_sta足可以取代EGM2008重力场模型2~100阶次的低阶部分,新得到的稳态重力场模型可为海面地形分析提供了可靠的参考场。 相似文献
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应用输入输出法逼近局部重力场的关键在于构建有效反映局部重力场特征的功率谱密度函数模型、利用"间接法",基于Moritz协方差模型、Tscherning/Rapp协方差模型和Moritz两分量模型分别构建对应的功率谱密度函数模型,并采用非线性最小二乘法在EGM2008模型的基础上拟合了模型系数。拟合结果表明:在2倍相关长度的相关距离内,Moritz两分量模型求得的理论协方差值与经验协方差值的符合度最好。设计了以EGM2008模型重力异常为基础数据,计算大地水准面高的仿真实验。结果表明:三种模型中,Moritz两分量模型的计算结果精度最高,同传统Stokes方法的计算结果精度相当,与拟合的理论协方差曲线图所反映的结果一致。 相似文献
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分析了重力卫星数据构建的地球重力场模型EIGEN-CHAMP03S(140)、ITG-Grace2010s(180)、GO_CONS(240)、GOCO02s(250)的内符合精度,还与综合性地球重力场模型(EGM2008)进行了比较。然后,选用我国范围内854个AB级GPS/水准点,检核各模型分阶次确定的高程异常与实测值之间的差异,以体现其外符合精度。结果表明:以重力卫星数据构建地球重力场模型能以较高精度来表征重力场的中长波部分,与EGM2008模型的精度相当。在我国范围内,计算似大地水准面都能够达到米级精度,其中GOCO02s(250)模型精度最好,能达到0.5m的精度。 相似文献
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重力垂直梯度异常反应了重力异常的空间变化率,在地球物理勘探等多学科中得到越来越多的应用。利用南海局部区域实测重力异常数据和Sandwell测高重力异常数据,将搜索范围、距离和精度多种因素融合考虑并对Shepard算法进行改进,给出了南海局部区域(19°N~20.5°N,114°E~115.5°E)分辨率1'×1'的重力异常并反演了对应分辨率的重力垂直梯度异常。结果表明,基于Shepard改进算法的高精度船测重力和测高重力的有机融合,增强了单一测高重力数据反演重力垂直梯度异常的细节纹理,提高了反演重力垂直梯度异常的分辨率和精度。 相似文献
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联合T/P、ERS1/GM、ERS1/ERM、ERS2/ERM、GEOSAT/ERM、GEOSAT/GM等多源卫星测高数据,基于逆Vening-Meinesz公式和EGM2008模型,采用移去-恢复方法和快速傅里叶变换算法构建了中国西太平洋海域(0°~40°N,105°E~145°E)1'×1'重力异常模型,选取两个不同特征区域航线,将构建的重力异常模型、EGM2008重力异常模型、美国Scripps海洋研究所重力异常与船测重力数据进行比较分析。结果表明,构建的重力异常模型与船测重力总体趋势变化较为一致、与船测重力比较均方根差为4.16m Gal,总体精度与EGM2008模型重力异常、美国Scripps海洋研究所重力异常相当,反演精度和分辨率达到国际领先水平。 相似文献
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根据体谐函数一阶、二阶水平导数(广义球函数)也是球面正交函数系的性质,详细推导了水平重力梯度边值问题的级数解.根据扰动位与重力场元的微分关系,导出了由水平重力梯度计算重力异常、垂线偏差的公式.完善了全张量重力梯度的有关应用. 相似文献
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简述了SGG数据恢复局部重力场的理论本质以及卫星重力梯度边值问题;详细介绍了当前国内外利用SGG进行局部重力场求解的研究进展,并将已有的求解方法总结归纳为三类:模型法、计算法和组合法,同时对各种方法的概念和研究现状作了详细介绍;最后总结了SGG数据求解局部重力场的发展前景和思考建议。 相似文献
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This is a review article on the types of gravity-measuring instruments used or tested at sea since 1903, on the various extraneous accelerations that affect sea measurements, and on results obtained in several gravity surveys using one type of meter. Free-air gravity anomaly maps are included of: (1) the Gulf of Mexico; (2) a strip west of the coast from northern California to the southern tip of Alaska; and (3) north of Hawaii. Hypothetical crustal and subcrustal sections, consistent with gravity anomalies and seismic refraction data, are included for selected regions. 相似文献
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Kern E. Kenyon 《Journal of Oceanography》1997,53(1):89-92
The effects of the gravity torques acting on the angular momentum of surface gravity waves are calculated theoretically. For
short crested waves the gravity torque is caused by the force of gravity on the orbiting fluid particles acting down the slopes
of the crests and troughs and in the direction parallel to the crests and troughs. The gravity torque tries to rotate the
angular momentum vectors, and thus the waves themselves, counterclockwise in the horizontal plane, as viewed from above, in
both hemispheres. The amount of rotation per unit time is computed to be significant assuming reasonable values for the along-crest
and trough slopes for waves in a storm area. The gravity torque has a frequency which is double the frequency of the waves.
For long crested waves the gravity torque acts in the vertical plane of the orbit and tries to decelerate the particles when
they rise and accelerate them when they fall. By disrupting the horizontal cyclostrophic balance of forces on the fluid particles
(centrifugal force versus pressure force) the gravity torque accounts qualitatively for the three characteristics of breaking
waves: that they break at the surface, that they break at the crest, and that the crest breaks in the direction of wave propagation. 相似文献
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F. J. Davey 《Marine Geophysical Researches》1972,1(4):428-435
Gravity measurements in the South Atlantic Ocean over Burdwood Bank show a large negative gravity anomaly extending along its northern edge. An interpretation of the gravity data has been made based on the seismic refraction measurements of Ludwig et al. (1968) and shows that the negative gravity anomaly can be largely attributed to a basin containing low density sediments about 8 km thick. The crustal sections constructed also indicate that the crust increases in thickness from about 20 km under Burdwood Bank to about 30 km under the Falkland Islands platform. 相似文献
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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