共查询到20条相似文献，搜索用时 62 毫秒
1.
双星伴飞卫星测高模式及其轨道设计 总被引：1，自引：0，他引：1
为达到提高反演海洋重力场分辨率的要求,本文提出一种双星伴飞的测高卫星模式,并根据卫星轨道设计的基本要求,给出相应的卫星轨道设计方案。仿真分析表明,该方案可在卫星设计寿命内完成反演1′×1′空间分辨率海洋重力场的要求,且观测数据覆盖了全球大部分海洋区域。该模式可实现星下点海平面梯度的实时测量,提出了改进测高反演海洋重力场的精度的新思路。 相似文献
2.
J. Klokočník Ch. Reigber P. Schwintzer C. A. Wagner J. Kostelecký 《Journal of Geodesy》2002,76(4):189-198
The new GFZ/GRGS gravity field models GRIM5-S1 and GRIM5-C1, currently used as initial models for the CHAMP mission, have
been compared with other recent models (JGM 3, EGM 96) for radial orbit accuracy (by means of latitude lumped coefficients)
in computations on altimetry satellite orbits. The bases for accuracy judgements are multi-year averages of crossover sea
height differences from Geosat and ERS 1/2 missions. This radially sensitive data is fully independent of the data used to
develop these gravity models. There is good agreement between the observed differences in all of the world's oceans and projections
of the same errors from the scaled covariance matrix of their harmonic geopotential coefficients. It was found that the tentative
scale factor of five for the formal standard deviations of the harmonic coefficients of the new GRIM fields is justified,
i.e. the accuracy estimates, provided together with the GRIM geopotential coefficients, are realistic.
Received: 20 February 2001 / Accepted: 24 October 2001 相似文献
3.
Over the past three decades, radar altimetry has made a significant contribution to marine gravity field modeling. To improve the accuracy and resolution, we propose a new twin-satellite altimetry. Such a system has several advantages. Among others, it provides (i) twice the number of samples per time epoch, and (ii) information about the cross-track surface gradient with high accuracy because most of the environmental and tidal errors will be common to the simultaneous measurements and therefore cancel out when computing the cross-track gradient computation. We describe a rigorous procedure for the deduction of the sea surface gradient at each altimeter observation point (i.e., not only at the crossovers), from the twin-satellite altimetry system. The precision of the gradient will be slightly affected by orbit errors, instrument drift, and inaccuracies in the geophysical corrections to be applied. We also demonstrate that a 1 mGal accuracy and 1 min resolution marine altimetry gravity field can be obtained if certain conditions are met. To achieve the expected goal, we recommend an orbital configuration, phasing two satellites in 4-s time delay such that the Earth rotation creates a natural baseline between the two satellites, and a 18 kHz SAR altimeter. 相似文献
4.
根据自主海洋测高卫星发展需求,设计了双星串飞运行模式,该运行模式下2.3 a时间可满足全球海洋区域1'×1'分辨率的地面轨迹覆盖要求。首先,将测高卫星重力场反演分为不考虑轨道运行特点（思路1）和考虑串飞轨道运行特点（思路2）两种思路,利用逆Vening-Meinesz方法开展了正态分布下随机误差传播的仿真计算,获得了两种思路下对应的误差指标。以该误差指标为基础,分别计算了双星串飞模式下两种重力场反演思路对应的精度指标。其中,反演思路2充分利用了串飞模式双星东西方向地面观测值可以进行相对定轨的特点,并考虑到近距离条件下传播误差、地球物理改正误差的系统误差特性,因此反演思路2的垂线偏差精度较反演思路1有了一定的提高,其重力场反演也具有一定的优势。理论计算结果表明,利用思路1的反演方法,2.3 a时间可获得1'×1'重力异常精度为6~10 mGal,4.6 a时间可达到4.2~7.1 mGal;利用思路2的反演方法,2.3 a时间可获得1'×1'重力异常精度为3.9 mGal,4.6 a时间可达到2.8 mGal。 相似文献
5.
The determination of local geoid models has traditionally been carried out on land and at sea using gravity anomaly and satellite
altimetry data, while it will be aided by the data expected from satellite missions such as those from the Gravity field and
steady-state ocean circulation explorer (GOCE). To assess the performance of heterogeneous data combination to local geoid
determination, simulated data for the central Mediterranean Sea are analyzed. These data include marine and land gravity anomalies,
altimetric sea surface heights, and GOCE observations processed with the space-wise approach. A spectral analysis of the aforementioned
data shows their complementary character. GOCE data cover long wavelengths and account for the lack of such information from
gravity anomalies. This is exploited for the estimation of local covariance function models, where it is seen that models
computed with GOCE data and gravity anomaly empirical covariance functions perform better than models computed without GOCE
data. The geoid is estimated by different data combinations and the results show that GOCE data improve the solutions for
areas covered poorly with other data types, while also accounting for any long wavelength errors of the adopted reference
model that exist even when the ground gravity data are dense. At sea, the altimetric data provide the dominant geoid information.
However, the geoid accuracy is sensitive to orbit calibration errors and unmodeled sea surface topography (SST) effects. If
such effects are present, the combination of GOCE and gravity anomaly data can improve the geoid accuracy. The present work
also presents results from simulations for the recovery of the stationary SST, which show that the combination of geoid heights
obtained from a spherical harmonic geopotential model derived from GOCE with satellite altimetry data can provide SST models
with some centimeters of error. However, combining data from GOCE with gravity anomalies in a collocation approach can result
in the estimation of a higher resolution geoid, more suitable for high resolution mean dynamic SST modeling. Such simulations
can be performed toward the development and evaluation of SST recovery methods. 相似文献
6.
The analysis of the time and space distribution of specular (reflecting) points in bistatic altimetry between GPS and CHAMP
satellites or SAC-C (taken as examples) is extended from Wagner and Klokočník (2003 J. Geod 77: 128–138). We demonstrate a
significantly higher number and density of reflecting points in bistatic altimetry in comparison with traditional monostatic
altimetry. After an outline of our older accuracy assessment for the vertical position of the reflecting point, we add a new
independent derivation and compare both approaches. We account for orbit errors of both the transmitters (GPS) and receiver
(CHAMP) satellites, and the measurement (delay) error. We found that the accuracy of the vertical position of the reflecting
point decreases only slowly with increasing off-nadir angle and that the orbit errors must be accounted for if decimeter and
better accuracy is required. In this paper, we do not study errors such as state of the ocean, technical parameters of the
receiving system, and atmospheric corrections. 相似文献
7.
Analysis of some systematic errors affecting altimeter-derived sea surface gradient with application to geoid determination over Taiwan 总被引：3，自引：1，他引：3
C. Hwang 《Journal of Geodesy》1997,71(2):113-130
This paper analyzes several systematic errors affecting sea surface gradients derived from Seasat, Geosat/ERM, Geosat/GM,
ERS-1/35d, ERS-1/GM and TOPEX/POSEIDON altimetry. Considering the data noises, the conclusion is: (1) only Seasat needs to
correct for the non-geocentricity induced error, (2) only Seasat and Geosat/GM need to correct for the one cycle per revolution
error, (3) only Seasat, ERS-1/GM and Geosat/GM need to correct for the tide model error; over shallow waters it is suggested
to use a local tide model not solely from altimetry. The effects of the sea surface topography on gravity and geoid computations
from altimetry are significant over areas with major oceanographic phenomena. In conclusion, sea surface gradient is a better
data type than sea surface height. Sea surface gradients from altimetry, land gravity anomalies, ship gravity anomalies and
elevation data were then used to calculate the geoid over Taiwan by least-squares collocation. The inclusion of sea surface
gradients improves the geoid prediction by 27% when comparing the GPS-derived and the predicted geoidal heights, and by 30%
when comparing the observed and the geoid-derived deflections of the vertical. The predicted geoid along coastal areas is
accurate to 2 cm and can help GPS to do the third-order leveling.
Received 22 January 1996; Accepted 13 September 1996 相似文献
8.
The ITG-Goce02 gravity field model from GOCE orbit and gradiometer data based on the short arc approach 总被引：1，自引：1，他引：0
In this contribution, we describe the global GOCE-only gravity field model ITG-Goce02 derived from 7.5 months of gradiometer and orbit data. This model represents an alternative to the official ESA products as it is computed completely independently, using a different processing strategy and a separate software package. Our model is derived using the short arc approach, which allows a very effective decorrelation of the highly correlated GOCE gradiometer and orbit data noise by introducing a full empirical covariance matrix for each arc, and gives the possibility to downweight ‘bad’ arcs. For the processing of the orbit data we rely on the integral equation approach instead of the energy integral method, which has been applied in several other GOCE models. An evaluation against high-resolution global gravity field models shows very similar differences of our model compared to the official GOCE results published by ESA (release 2), especially to the model derived by the time-wise approach. This conclusion is confirmed by comparison of the GOCE models to GPS/levelling and altimetry data. 相似文献
9.
Christoph Förste Roland Schmidt Richard Stubenvoll Frank Flechtner Ulrich Meyer Rolf König Hans Neumayer Richard Biancale Jean-Michel Lemoine Sean Bruinsma Sylvain Loyer Franz Barthelmes Saskia Esselborn 《Journal of Geodesy》2008,82(6):331-346
The recent improvements in the Gravity Recovery And Climate Experiment (GRACE) tracking data processing at GeoForschungsZentrum
Potsdam (GFZ) and Groupe de Recherche de Géodésie Spatiale (GRGS) Toulouse, the availability of newer surface gravity data
sets in the Arctic, Antarctica and North-America, and the availability of a new mean sea surface height model from altimetry
processing at GFZ gave rise to the generation of two new global gravity field models. The first, EIGEN-GL04S1, a satellite-only
model complete to degree and order 150 in terms of spherical harmonics, was derived by combination of the latest GFZ Potsdam
GRACE-only (EIGEN-GRACE04S) and GRGS Toulouse GRACE/LAGEOS (EIGEN-GL04S) mean field solutions. The second, EIGEN-GL04S1 was
combined with surface gravity data from altimetry over the oceans and gravimetry over the continents to derive a new high-resolution
global gravity field model called EIGEN-GL04C. This model is complete to degree and order 360 and thus resolves geoid and
gravity anomalies at half- wavelengths of 55 km at the equator. A degree-dependent combination method has been applied in
order to preserve the high accuracy from the GRACE satellite data in the lower frequency band of the geopotential and to form
a smooth transition to the high-frequency information coming from the surface data. Compared to pre-CHAMP global high-resolution
models, the accuracy was improved at a spatial resolution of 200 km (half-wavelength) by one order of magnitude to 3 cm in
terms of geoid heights. The accuracy of this model (i.e. the commission error) at its full spatial resolution is estimated
to be 15 cm. The model shows a reduced artificial meridional striping and an increased correlation of EIGEN-GL04C-derived
geostrophic meridional currents with World Ocean Atlas 2001 (WOA01) data. These improvements have led to select EIGEN-GL04C
for JASON-1 satellite altimeter data reprocessing.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
10.
卫星测高在物理大地测量应用中的若干问题 总被引：4，自引：2，他引：4
总结了卫星测高在物理大地测量领域的应用，描述了卫星测高数据逼近地球重力场、确定海面地形、改善卫星轨道参数以及求解重力异常的数学模型和数学原理。 相似文献
11.
采用星载GPS观测数据与简化动力学定轨方法,在方程中引入伪随机脉冲参数,从而实现对Swarm卫星的精密定轨. 详细分析了不同阶次的GOCO06s地球重力场模型对Swarm卫星简化动力学定轨精度的影响,对比了PGM2000a、EIGEN-2、EGM2008以及GECO重力场模型展开到100阶次时Swarm卫星解算的轨道精度. 结果表明:当GOCO06s地球重力场模型阶次处于30～100阶次时,Swarm-A、Swarm-B和Swarm-C卫星在径向、切向、法向上的定轨精度随着GOCO06s阶次的不断增加而越来越高,而在高于100阶次时,定轨精度基本稳定,且在各方向定轨精度优于3 cm. 此外,采用100阶次GECO、EGM2008和GOCO06s模型对三颗Swarm卫星进行定轨,解算的轨道精度相当,且要高于同阶次其他重力场模型的定轨结果. 相似文献
12.
A technique is presented for the development of a high-precision and high-resolution mean sea surface model utilising radar
altimetric sea surface heights extracted from the geodetic phase of the European Space Agency (ESA) ERS-1 mission. The methodology
uses a cubic-spline fit of dual ERS-1 and TOPEX crossovers for the minimisation of radial orbit error. Fourier domain processing
techniques are used for spectral optimal interpolation of the mean sea surface in order to reduce residual errors within the
initial model. The EGM96 gravity field and sea surface topography models are used as reference fields as part of the determination
of spectral components required for the optimal interpolation algorithm. A comparison between the final model and 10 cycles
of TOPEX sea surface heights shows differences of between 12.3 and 13.8 cm root mean square (RMS). An un-optimally interpolated
surface comparison with TOPEX data gave differences of between 15.7 and 16.2 cm RMS. The methodology results in an approximately
10-cm improvement in accuracy. Further improvement will be attained with the inclusion of stacked altimetry from both current
and future missions.
Received: 22 December 1999 / Accepted: 6 November 2000 相似文献
13.
基于卫星加速度恢复地球重力场的去相关滤波法 总被引：3，自引：0，他引：3
基于加速度法恢复地球重力场时,卫星加速度是由卫星轨道数值微分得到,而数值微分会放大高频误差,进而降低了重力场解算结果的精度.针对数值微分导出的加速度误差具有有色噪声的特性,提出利用去相关算法构造白化滤波器对加速度有色噪声进行滤波处理,并根据去相关的基本原理分别构造了基于三点差分和ARMA模型的白化滤波器.采用不同噪声背景的CHAMP卫星模拟轨道数据进行解算,结果表明:基于去相关滤波解算的重力场模型精度均要比等权解算的重力场模型精度高,初步验证了去相关滤波方法的有效性. 相似文献
14.
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
15.
球近似下地球外空间任意类型场元的地形影响 总被引：1，自引：0，他引：1
传统的重力归算方法只适用于地球表面上的重力异常,不能用于扰动重力、垂线偏差、重力梯度等其他类型扰动重力场元,不适合处理除地面外其他高度上场元的地形影响问题。当前,地球重力场探测的场元类型越来越丰富,探测的高度也逐渐转向航空和卫星高度,精确处理地球外空间各种类型重力场元的地形影响已成为地球重力场领域面临的重要课题。本文通过直接分解由地形生成的具有调和性质的引力场,从而导出地球外空间任意高度、任意类型扰动重力场元的地形影响,在此基础上给出在球近似下地形影响的严密算法和高精度快速算法。利用本文推荐的地形影响计算方案,可以方便地处理各种类型地面重力、海洋重力、航空重力、卫星重力、卫星测高数据的地形影响,从而丰富重力场数据处理的内涵,改善地球重力场算法的性能。 相似文献
16.
天问一号是中国首次独立开展的行星际探测任务,实现了对火星的环绕、着陆、巡视探测。天问一号正常科学任务阶段环绕以极轨设计为主,与历史火星任务类似,对当前火星重力场模型精度改进有限,因此其拓展任务轨道选取至关重要。通过对极轨圆轨道和近赤道大偏心率轨道进行仿真模拟,分析两种典型轨道构型对现有火星重力场模型改进的可能性,基于不同误差考量仿真解算了对应6个重力场模型。借助重力场功率谱分析,发现在测量噪声为0.1 mm/s的情况下,不论采用极轨还是近赤道轨道,一个月的跟踪数据均可较好地反演出42阶次的火星重力场模型;考虑综合误差影响之后,发现两种轨道对于重力场解算精度类似,其中实施近赤道大偏心率轨道对35阶次以上约束略强。 相似文献
17.
航空重力测量数据含有许多噪声，需用高质量的数字滤波器加以平滑。有限冲激响应（ＦＩＲ）滤波器的优点是具有精确线性相位而且总是稳定的。本文利用契比雪夫逼近方法，设计了适用于航空重力测量的ＦＩＲ低通滤波器。为检测其性能，文中建立了一个模拟加速度模型。检测结果表明：滤波器性能可靠，适用于航空重力测量数据处理。 相似文献
18.
Validation of GOCE gravity field models by means of orbit residuals and geoid comparisons 总被引：6，自引：3，他引：3
Three GOCE-based gravity field solutions have been computed by ESA’s high-level processing facility and were released to the
user community. All models are accompanied by variance-covariance information resulting either from the least squares procedure
or a Monte-Carlo approach. In order to obtain independent external quality parameters and to assess the current performance
of these models, a set of independent tests based on satellite orbit determination and geoid comparisons is applied. Both
test methods can be regarded as complementary because they either investigate the performance in the long wavelength spectral
domain (orbit determination) or in the spatial domain (geoid comparisons). The test procedure was applied to the three GOCE
gravity field solutions and to a number of selected pre-launch models for comparison. Orbit determination results suggest,
that a pure GOCE gravity field model does not outperform the multi-year GRACE gravity field solutions. This was expected as
GOCE is designed to improve the determination of the medium to high frequencies of the Earth gravity field (in the range of
degree and order 50 to 200). Nevertheless, in case of an optimal combination of GOCE and GRACE data, orbit determination results
should not deteriorate. So this validation procedure can also be used for testing the optimality of the approach adopted for
producing combined GOCE and GRACE models. Results from geoid comparisons indicate that with the 2 months of GOCE data a significant
improvement in the determination of the spherical harmonic spectrum of the global gravity field between degree 50 and 200
can be reached. Even though the ultimate mission goal has not yet been reached, especially due to the limited time span of
used GOCE data (only 2 months), it was found that existing satellite-only gravity field models, which are based on 7 years
of GRACE data, can already be enhanced in terms of spatial resolution. It is expected that with the accumulation of more GOCE
data the gravity field model resolution and quality can be further enhanced, and the GOCE mission goal of 1–2 cm geoid accuracy
with 100 km spatial resolution can be achieved. 相似文献
19.
欧空局早期公布的时域法和空域法解算的GOCE模型均采用能量守恒法处理轨道数据, 但恢复的长波重力场信号精度较低, 而且GOCE卫星在两极存在数据空白, 利用其观测数据恢复重力场模型是一个不适定问题, 导致解算的模型带谐项精度较低, 需进行正则化处理。本文分析了基于轨道数据恢复重力场模型的方法用于处理GOCE数据的精度, 对最优正则化方法和参数的选择进行研究。利用GOCE卫星2009-11-01—2010-01-31共92 d的精密轨道数据, 采用不依赖先验信息的能量守恒法、短弧积分法和平均加速度法恢复GOCE重力场模型, 利用Tikhonov正则化技术处理病态问题。结果表明, 平均加速度法恢复模型的精度最高, 能量守恒法的精度最低, 短弧积分法的精度稍差于平均加速度法。未来联合处理轨道和梯度数据时, 建议采用平均加速度法或短弧积分法处理轨道数据, 并且轨道数据可有效恢复120阶次左右的模型。Kaula正则化和SOT处理GOCE病态问题的效果最好, 并且两者对应的最优正则化参数基本一致, 但利用正则化技术不能完全抑制极空白问题的影响, 需要联合GRACE等其他数据才能获得理想的结果。 相似文献
20.
动力学法的卫星重力反演算法特点与改进设想 总被引：1，自引：0，他引：1
根据卫星轨道计算的积分公式,导出了以参考轨道为初值的线性化解算地球重力场的观测方程,给出了其系数矩阵的积分计算公式,阐明了动力学法本质上是观测值相对于参考轨道的线性摄动方法,因此其变分方程力模型参数的偏导数初值必定为0。在此公式的基础上,分析了动力学法观测方程的主要特点,即线性化误差随轨道弧段增长而快速增大,其观测方程的性质也随弧段增长而变差,且积分计算误差将是下一代重力卫星数据处理的重要瓶颈问题。提出了进一步提高动力学法重力反演精度的方法,主要归结为:改进以几何轨道为初值的线性化方法以减小线性化误差,改变参数化方式以改善观测方程的性质,综合应用解析公式与数值积分公式以提高轨道计算精度。 相似文献