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1.
G. Blaha 《Journal of Geodesy》1977,51(1):33-45
The short arc adjustment mode makes a determination of the geoid surface possible without the requirement of highly precise
reference orbits. In this mode, the state vector components are subject to adjustment and represent in fact a set of independent
weighted parameters. In a most elementary approach, the radial distance to a satellite point is differentiated with respect
to these parameters and a radial distance to the geoid (r) is differentiated with respect to the earth potential coefficients.
The observed satellite altimetry value (H) is approximately equal to the difference between these two radial distances. In
the present study, a correction is introduced that makes it possible to express the mathematical model for H as accurately
as practicable, good to a few centimeters. With regard to the partial differentiation, it is argued that r, in addition to
being differentiated with respect to the potential coefficients, has to be differentiated also with respect to the state vector
components. This gives rise to a second type of correction. It is shown that for most practical purposes, the ellipsoidal
approximation to the geoid used to compute the above two kinds of corrections is satisfactory. The final results indicate
that actual computation of these corrections is a very simple matter; an eventual upgrading of satellite altimetry computer
programs can thus be accomplished with almost no additional effort. A practical benefit of the presented analysis is faster
convergence in the adjustment which, in some cases, may remove the need for iterated solutions altogether. 相似文献
2.
卫星测高与卫星重力对洋流的研究 总被引:2,自引:0,他引:2
卫星测高与卫星重力的发展为进一步研究洋流提供了前所未有的机遇。本文从EGM 96 ,GGM0 1与未来的GOCE任务获取的高精度高分辨率海洋大地水准面的角度对洋流的研究方法与可行性进行了分析 相似文献
3.
Elke Stöcker-Meier 《Journal of Geodesy》1990,64(3):247-258
The problem of improving the geoid from satellite altimetry is formulated and studied within the scope of geophysical fluid
dynamics. The oceanic levelling is defined by analogy to the astrogeodetic levelling and it is used to determine the sea surface
topography as a function of current velocity, atmospheric pressure and viscosity. Simulating strong currents like the Gulf
Stream or the Kuroshio the numerical treatment of the oceanic levelling shows that the sea surface topography can come up
to an order of magnitude of1–2 m, whereby the results depend on latitude and slightly on the actual pressure conditions. 相似文献
4.
5.
地基完好性监测是利用四个或四个以上的精确坐标的监测站对卫星进行监测,计算其星历及星钟误差。该方法需满足四重以上监测站覆盖条件,对于自主导航和区域布站的导航系统不能实现导航卫星的全弧段完好性监测。对于不满足上述覆盖条件的卫星,采用基于星间链路的监测方法,利用四个或四个以上的具有一定坐标误差的卫星对该卫星进行监测。通过星历数据和星间测距数据计算SISMA,从而进行导航卫星全弧段的完好性监测。 相似文献
6.
利用卫星测高资料推求西北太平洋海域的海洋大地水准面 总被引:3,自引:0,他引:3
本文根据卫星测高数据和海面动力地形资料,绘制了不相上下北太平洋海域局部大地水准面的精细结构图,对解决卫星测高技术中大地水准面积和海面地形的可分性问题作了初步尝试。 相似文献
7.
Mission design,operation and exploitation of the gravity field and steady-state ocean circulation explorer mission 总被引:6,自引:3,他引:3
The European Space Agency’s Gravity field and steady-state ocean circulation explorer mission (GOCE) was launched on 17 March
2009. As the first of the Earth Explorer family of satellites within the Agency’s Living Planet Programme, it is aiming at
a better understanding of the Earth system. The mission objective of GOCE is the determination of the Earth’s gravity field
and geoid with high accuracy and maximum spatial resolution. The geoid, combined with the de facto mean ocean surface derived
from twenty-odd years of satellite radar altimetry, yields the global dynamic ocean topography. It serves ocean circulation
and ocean transport studies and sea level research. GOCE geoid heights allow the conversion of global positioning system (GPS)
heights to high precision heights above sea level. Gravity anomalies and also gravity gradients from GOCE are used for gravity-to-density
inversion and in particular for studies of the Earth’s lithosphere and upper mantle. GOCE is the first-ever satellite to carry
a gravitational gradiometer, and in order to achieve its challenging mission objectives the satellite embarks a number of
world-first technologies. In essence the spacecraft together with its sensors can be regarded as a spaceborne gravimeter.
In this work, we describe the mission and the way it is operated and exploited in order to make available the best-possible
measurements of the Earth gravity field. The main lessons learned from the first 19 months in orbit are also provided, in
as far as they affect the quality of the science data products and therefore are of specific interest for GOCE data users. 相似文献
8.
9.
广播星历参数拟合算法研究 总被引:7,自引:0,他引:7
导航卫星一般采用近圆轨道,当卫星轨道偏心率或者轨道倾角接近于0时,利用GPS卫星开普勒轨道根数拟合卫星广播星历会出现一些问题。当高轨卫星轨道偏心率接近0时,广播星历拟合精度下降甚至拟合失败,为此本文提出了减少拟合参数个数、固定轨道根数M0或者延长星历参数拟合弧段长度的方法;针对GEO卫星在小倾角情况下,广播星历可能拟合失败的情况,本文提出了改变坐标系参考轨道面,在新的坐标系下拟合广播星历的方法。结果表明,改进后的拟合方法能适用于各种类型的导航卫星轨道,拟合精度在cm级或者mm级。 相似文献
10.
星基增强系统(satellite based augmentation system,SBAS)通过地球同步轨道卫星实时播发导航卫星星历改正数和完好性参数,以提升用户定位精度和完好性.采用最小方差法解算GPS星历改正数,利用卡方统计进行改正数完好性检核,并依据星历改正数方差-协方差信息计算SBAS用户差分距离误差(us... 相似文献
11.
介绍了目前国际全球定位系统服务(IGS)组织提供的实时精密轨道和精密钟差改正系数(ROCC)的基本参数以及能够进行实时精密单点定位软件(BNC)(即BKG Ntrip Client,由BKG开发的一款用于实时同步接收、解码及转换的GNSS数据流管理软件)。选取了25个全球IGS跟踪站,并基于BNC软件分析了IGS提供的15种ROCC产品对测站实时精密单点定位精度与收敛性的影响。实验结果表明:采用BNC软件,15种ROCC产品均能在平均15min的时间收敛,并且在N、E方向达到6~8cm,U方向10~20cm的定位精度;且不同ROCC产品其收敛时间和定位精度都存在一定的差异。 相似文献
12.
13.
G. Blaha 《Journal of Geodesy》1978,52(3):191-198
The radial distance (length of a position vector) from the geocenter to the geoid as defined by the spherical harmonic potential
coefficients is needed e.g. in the process of adjusting satellite altimeter data. The geocentric latitude and longitude associated
with this distance are assumed known—in this case derived from satellite altimetry. Typically, the radial distance can be
computed to a desired accuracy in an iterative process. Even if a crude initial value is adopted, a sub-meter accuracy is
achieved on the second iteration, while the third iteration yields a sub-millimeter accuracy. If the best possible initial
value is taken, such as the radial distance to the mean earth ellipsoid, the iterative process may be accelerated by one iteration.
But even then two iterations will be needed in most cases. However, an algorithm has been designed that yields excellent results,
characterized by a sub-centimeter accuracy, already from the first iteration. It results in important computer savings, considering
that in real data reductions of satellite altimetry, the radial distance needs to be computed at thousands of locations. 相似文献
14.
15.
A kinematic GPS methodology for sea surface mapping,Vanuatu 总被引:1,自引:0,他引:1
Marie-Noelle Bouin Valérie Ballu Stéphane Calmant Jean-Michel Boré Eric Folcher Jérôme Ammann 《Journal of Geodesy》2009,83(12):1203-1217
During the past few decades, satellite altimetry has brought tremendous new knowledge about the spatial and temporal variations
of sea surface heights over the Earth’s oceans. However, the precision is limited over short wavelengths and in coastal areas,
and other methods such as kinematic GPS may be needed to fill in this information. We present kinematic GPS work aimed at
mapping the sea surface height, with special attention to the precision one can expect. Active marine subduction zones, like
the Vanuatu archipelago, may present short wavelength, high amplitude undulations of the sea surface height that are difficult
to map with satellite altimetry. This paper presents the methodology used around Santo Island, in Vanuatu, to obtain a well-resolved
local sea surface map with a precision of 5–15 cm limited by the sea conditions and the distance from the coastal reference
station. We present the results of three campaigns in 2004, 2006 and 2007. Careful observation of the ship behaviour along
the surveys as well as simultaneous recording of the ship attitude variations is mandatory to obtain reliable results. We
show that the ship GPS antenna height varies with the ship’s velocity and we suggest a method to correct this effect. The
final precision is estimated using the crossover differences method. 相似文献
16.
海洋卫星测高在全球和区域大地水准面建模、全球海洋重力场反演、海底地形探测、海平面变化监测、构造板块运动研究等大地测量领域至关重要。本文概述了海洋微波测高卫星的简要发展历程,重点梳理了卫星测高在全球海洋重力场和全球海底地形建模方面取得的丰硕成果,对比分析了主流的海洋重力场和海底地形模型;介绍了合成孔径雷达高度计、Ka频段雷达高度计、合成孔径雷达干涉仪3种先进微波测高技术,并分析了其各自的优缺点,表明它们将在未来若干年呈并驱发展趋势;较为系统地阐述了海洋卫星测高的另一新型技术,即GNSS反射信号测量技术的研究动态,给出了GNSS-R(GNSS reflectometry)类(试验)卫星的发展脉络和发展前景。卫星测高的发展趋势之一是多颗测高卫星的组网观测,本文概括了曾经提出的和拟议中的若干组网测高计划,扼要介绍了由我国提出并正在实施的双星跟飞测高模式;最后指出了卫星测高发展的几个主要关注点,包括双星跟飞测高和SWOT(surface water ocean topography)任务的2维海面高(差)测量、卫星测高反演海底地形与高级地形激光高度计观测数据及遥感卫星图像的结合、星载GNSS-R厘米级海面高的载波相位测量、人工智能技术在卫星测高中的潜在应用等。 相似文献
17.
The geodetic boundary value problem is formulated which uses as boundary values the differences between the geopotential of
points at the surface of the continents and the potential of the geoid. These differences are computed by gravity measurements
and levelling data. In addition, the shape of the geoid over the oceans is assumed to be known from satellite altimetry and
the shape of the continents from satellite results together with three-dimensional triangulation. The boundary value problem
thus formulated is equivalent to Dirichlet's exterior problem except for the unknown potential of the geoid. This constant
is determined by an integral equation for the normal derivative of the gravitational potential which results from the first
derivative of Green's fundamental formula. The general solution, which exists, of the integral equation gives besides the
potential of the geoid the solution of the geodetic boundary value problem. In addition approximate solutions for a spherical
surface of the earth are derived. 相似文献
18.
Gravity anomalies from satellite altimetry: comparison between computation via geoid heights and via deflections of the vertical 总被引:3,自引:0,他引:3
The accumulation of good quality satellite altimetry missions allows us to have a precise geoid with fair resolution and to compute free air gravity anomalies easily by fast Fourier transform (FFT) techniques.In this study we are comparing two methods to get gravity anomalies. The first one is to establish a geoid grid and transform it into anomalies using inverse Stokes formula in the spectral domain via FFT. The second one computes deflection of the vertical grids and transforms them into anomalies.The comparison is made using different data sets: Geosat, ERS-1 and Topex-Poseidon exact repeat misions (ERMs) north of 30°S and Geosat geodetic mission (GM) south of 30°S. The second method which transforms the geoid gradients converted into deflection of the vertical values is much better and the results have been favourably evaluated by comparison with marine gravity data. 相似文献
19.
Richard J. Anderle 《Journal of Geodesy》1980,54(4):521-527
The error in the mean earth ellipsoid computer on the basis of Doppler or laser observations of artificial earth satellites
or radar altimeter observations of the ocean surface from a satellite depends upon instrument precision, on uncertainties
in the specification of the earth's gravity field at both long and short wave lengths, on uncertainties in the origin of the
coordinate system, on modeling errors in ionospheric (except laser) and tropospheric refraction, and, for altimetry, on oceanographic
effects. The magnitude of the uncertainty in the computed ellipsoid will vary depending on the size of these errors and on
the number and distribution of observation stations. Review of computations based on various data sets indicates that differences
in the computed ellipsoids are consistent with those expected due to the various error sources and that the best fitting ellipsoid
has a semi-major axis of6378136±2 m. 相似文献
20.
基于第一类无奇点根数的LEO历书参数设计 总被引:1,自引:0,他引:1
GNSS技术蓬勃发展,在国防建设和国民经济发展中发挥了重要作用。但也因其无法快速解算整周模糊度、复杂环境下适应性差、完好性差等缺点,限制了其作用的最大发挥。基于LEO通信卫星星座的系统增强可以很好地克服这些缺点。要实现该增强系统,基础之一就是如何生成LEO卫星的历书星历。为解决这个问题,从第一类无奇点出发对GPS标准历书进行改造,提出了一套专用于LEO卫星的10参数历书集,并推导了历书计算公式。对600~1 500 km轨道高度的2~7 d的LEO卫星轨道进行了拟合实验。结果表明,高度600 km时长2 d,高度700 km时长4 d,高度800 km时长7 d历书拟合的用户距离误差(URE)的均方根误差(RMS)分别优于936.021,944.087和956.183 m。 相似文献