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基线长度变化率反映了测站间的地壳运动情况.采用国际空间数据分析中心提供的GPS和VLBI实测站速度数据,解算了并置站间的基线长度变化率.并置站间不同技术测定的地壳运动的相互比较,可以发现不同技术测定地壳运动的系统差.研究结果表明,VLBI基线长度变化率比GPS的相应值系统性地偏大约2%,GPS基线长度变化率比VLBI的相应值快一个常值(约0.6 mm/a). 相似文献
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2011年8月在新疆天文台南山观测站首次进行了GPS与VLBI空间大地测量技术并置站的本地连接测量。针对南山并置站,本文在建立、优化南山GPS控制网的基础上,探讨本地连接测量中GPS数据处理的方法、精度。通过对GPS控制网7 d连续观测和基于IGS精密星历的GAMIT基线处理、三维空间平差,结果表明:基线在N、E和长度方向的重复性在0.3~0.4 mm,U方向分量重复性为1.4 mm,基线相对精度为0.8×10-8,达到《全球定位系统(GPS)测量规范》(GB/T 18314—2009)中A级网的精度要求,GPS控制点在ITRF2008系统下的坐标精度均优于0.5 mm。 相似文献
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针对甚长基线干涉测量(VLBI)技术中,测站坐标精度与高精度的VLBI宽带观测不相匹配的问题,该文提出一种利用VLBI本身观测结果分析测站坐标改正量的方法。利用观测得到的时延值扣除几何时延及各种已知误差项后,残余部分还存在由基线矢量误差引起的时延、两地原子钟同步误差和系统误差引起的时延,给出残余时延与基线矢量误差等的计算模型。采用国家授时中心VLBI2010系统观测数据,计算结果表明,吉林-喀什基线的基线长度改正量约为11.467 7cm,观测值与拟合值的对比表明这种方法的可行性。 相似文献
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并址技术是指在同一测站位置同时利用GPS、SLR、VLBI等不同空间定位技术进行观测的方法。本文利用上海台站并址的GPS、SLR、VLBI技术观测近10年的数据对台站所处地壳垂直运动进行监测,发现不同技术手段对相同地理位置地壳运动监测结果存在相似性,同时也有一定程度的差异,针对这种现象本文进行了分析与探讨。 相似文献
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南极大陆被横贯南极的山脉分为东南极和西南极,东西南极地质条件各异,但均属南极洲板块,大量学者对南极板块与地壳运动规律进行了研究,研究方法多以GPS站坐标为分析依据。本文利用GAMIT软件对南极板块内部IGS参考站10年的观测数据进行了GPS基线解算,通过对基线长度的变化分析,对南极板块的稳定性进行了研究,结果表明,10年间各参考站之间基线长度无明显变化,平均年变化率约为1 mm,东西南极各站基本无相对运动,南极板块内部相对稳定。 相似文献
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《测绘科技情报》2008,(2)
与之前的国际地球参考框架(ITRF)将全球长期解作为输入数据进行组合不同,ITRF2005将测站坐标(卫星技术每星期的数据和VLBI每24小时的数据)和每天的地球自转参数(EOPs)作为输入数据。使用测站位置时间序列的优势在于可以监控测站的非线性运动和非连续性,并检验框架物理参数即原点和尺度的时变特性。ITRF2005原点定义为:相对于由SLR技术13年的观测数据所得的地球质心的平移和平移速度为零;尺度定义为:相对于由VLBI技术26年的观测数据所得的尺度及其变化率为零;ITRF2005的定向(2000.0历元)及其速率与ITRF2000中70个高质量的测站一致。ITRF2005原点(2000.0历元)及其速率相对于ITRF2000沿X,Y,Z轴在0.1,0.8,5.8mm和0.2,0.1,1.8mm/y的水平上一致,其分量的误差分别为0.3mm和0.3mm/y。两个参考框架原点间一致性差可能是因为SLR网的几何图形差。ITRF2005组合中包含了84个并置站,尺度的不一致性在2000.0历元为1ppb(赤道处为6.3mm),SLR和VLBI由各自时间序列堆栈得到的长期解之间尺度不一致性为0.08ppb/yr。这些不一致性可能是因为SLR和VLBI网形差、并置站质量不好、局部联系的不确定性、系统误差影响以及数据分析中模型改正的不一致性。ITRF历史上,ITRF2005第一次采用了紧组合的方式给出了与之相一致的EOP序列,包括由VLBI和卫星技术得到的极移和仅从VLBI得到的UT和日长数据。 相似文献
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Analysis of the EUREF-89 GPS data from the SLR/VLBI sites 总被引：1，自引：0，他引：1
In May 1989, the IAG Subcommission for the European Reference Frame organized a GPS measurement campaign, called EUREF-89, to establish a common European Reference Frame. During a 2-week period various types of GPS receivers were deployed at about 100 different locations in Europe, which included many national geodetic first order points and most of the well-known SLR and VLBI sites. In this study, the measurements from those SLR and VLBI sites, and three additional points in The Netherlands, have been analyzed adopting a fiducial network approach. In the first place, the study provided valuable experience in the use of the GIPSY software for the analysis of GPS data from large networks equipped with a mixture of receiver types. Furthermore, this analysis represents an independent check of the SLR/VLBI network, used as the reference frame for the official EUREF solution. Daily solutions of baselines up to 2500 km in length have been obtained with a repeatability of 0.5–2.0 parts in 108, while the agreement with SLR results is at about the same level. The accuracy of the estimated coordinates is at a level of about 4.0 cm in the horizontal and 6.0 cm in the vertical direction. Of particular interest are the results for some baselines in Greece, which have also been measured by mobile SLR in the framework of the WEGENER/MEDLAS project. The GPS results seem to confirm the trends in the baseline length changes emerging from those SLR studies. 相似文献
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B. Schutz M. Bevis F. Taylor D. Kuang P. Abusali M. Watkins J. Recy B. Perin O. Peyroux 《Journal of Geodesy》1993,67(4):224-240
The Southwest Pacific GPS Project (SWP) is using the Global Positioning System (GPS) to monitor crustal motion across and within a plate boundary complex between the Australian and Pacific plates. GPS field campaigns were conducted in 1988, 1989 and 1990, to observe networks of increasing size and complexity. The 1990 campaign consisted of two periods, or Bursts, and this paper focuses on the analysis of data collected during the nine day Burst 1 in July, 1990, a period in which GPS Selective Availability was activated. During Burst 1, baselines that spanned the Tonga Trench and the Lau Basin were observed, and only one station (Espiritu Santo, Vanuatu) was located west of Fiji in the network. The lengths of the baselines observed fall mainly between 300 km and 1600 km, but some lines are as long as 3500 km. A total of 78 station-days of field site data and approximately 150 station-days of global fiducial data were processed from predominantly codeless receivers. A global fiducial network of 20 sites was used to provide orbit control and accuracy assessment for the 13 available satellites. The daily solutions for 45 baselines between 10 SWP sites have an RMS scatter in the length of 24 mm plus 6 parts per billion. This scatter provides an estimate of baseline precision for the Burst 1 nominal solution. Experiments were conducted to investigate a variety of possible effects on the SWP Network baseline estimates, including the influence of a reduced global fiducial network for the purpose of assessing the quality of results obtained in 1988 and 1989 in which the fiducial network was smaller than in 1990. These experiments produced results that agreed with the nominal solution at the level of the precision estimate. Furthermore, estimates for selected baselines in Australia, the Central Pacific, North America and Europe, also measured by VLBI and SLR, were used for an external accuracy evaluation. The GPS and VLBI or SLR determinations of length agreed at a level consistent with the nominal solution precision estimate. 相似文献
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Multi-technique comparison of tropospheric zenith delays derived during the CONT02 campaign 总被引：2，自引：7，他引：2
In October 2002, 15 continuous days of Very Long Baseline Interferometry (VLBI) data were observed in the Continuous VLBI 2002 (CONT02) campaign. All eight radio telescopes involved in CONT02 were co-located with at least one other space-geodetic technique, and three of them also with a Water Vapor Radiometer (WVR). The goal of this paper is to compare the tropospheric zenith delays observed during CONT02 by VLBI, Global Positioning System (GPS), Doppler Orbitography Radiopositioning Integrated by Satellite (DORIS) and WVR and to compare them also with operational pressure level data from the European Centre for Medium-Range Weather Forecasts (ECMWF). We show that the tropospheric zenith delays from VLBI and GPS are in good agreement at the 3–7 mm level. However, while only small biases can be found for most of the stations, at Kokee Park (Hawaii, USA) and Westford (Massachusetts, USA) the zenith delays derived by GPS are larger by more than 5 mm than those from VLBI. At three of the four DORIS stations, there is also a fairly good agreement with GPS and VLBI (about 10 mm), but at Kokee Park the agreement is only at about 30 mm standard deviation, probably due to the much older installation and type of DORIS equipment. This comparison also allows testing of different DORIS analysis strategies with respect to their real impact on the precision of the derived tropospheric parameters. Ground truth information about the zenith delays can also be obtained from the ECMWF numerical weather model and at three sites using WVR measurements, allowing for comparisons with results from the space-geodetic techniques. While there is a good agreement (with some problems mentioned above about DORIS) among the space-geodetic techniques, the comparison with WVR and ECMWF is at a lower accuracy level. The complete CONT02 data set is sufficient to derive a good estimate of the actual precision and accuracy of each geodetic technique for applications in meteorology. 相似文献
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Seasonal and secular positional variations at eight co-located GPS and VLBI stations 总被引：2，自引：0，他引：2
Time series of daily position solutions at eight co-located GPS and VLBI stations are used to assess the frequency features in the solutions over various time-scales. This study shows that there are seasonal and inter-annual signals in all three coordinate components of the GPS and VLBI solutions. The power and frequency of the signals vary with time, the station considered and the coordinate components, and between the GPS and VLBI solutions. In general, the magnitudes of the signals in the horizontal coordinate components (latitude and longitude) are weaker than those in the height component. The weighted means of the estimated annual amplitudes from the eight GPS stations are, respectively, 1.0, 0.8 and 3.6 mm for the latitude, longitude and height components, and are, respectively, 1.5, 0.7 and 2.2 mm for the VLBI solutions. The phases of the annual signals estimated from the GPS and VLBI solutions are consistent for most of the co-located stations. The seasonal signals estimated from the VLBI solutions are, in general, more stable than those estimated from the GPS solutions. Fluctuations at inter-annual time-scales are also found in the series. The inter-annual fluctuations are up to ∼5 mm for the latitude and longitude components, and up to ∼10 mm for the height component. The effects of the seasonal and inter-annual variations on the estimated linear rates of movement of the stations are also evaluated. 相似文献
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We have compared the VLBI and GPS terrestrial reference frames, realized using 5 years of time-series observations of station positions and polar motion, with surveyed co-location tie vectors for 25 sites. The goal was to assess the overall quality of the ties and to determine whether a subset of co-location sites might be found with VLBI–GPS ties that are self-consistent within a few millimeters. Our procedure was designed to guard against internal distortion of the two space-geodetic networks and takes advantage of the reduction in tie information needed with the time-series combination method by using the very strong contribution due to co-location of the daily pole of rotation. The general quality of the available ties is somewhat discouraging in that most have residuals, compared to the space-geodetic frames, at the level of 1–2 cm. However, by a careful selection process, we have identified a subset of nine local VLBI–GPS ties that are consistent with each other and with space geodesy to better than 4 mm (RMS) in each component. While certainly promising, it is not possible to confidently assess the reliability of this particular subset without new information to verify the absolute accuracy of at least a few of the highest-quality ties. Particular care must be taken to demonstrate that possible systematic errors within the VLBI and GPS systems have been properly accounted for. A minimum of two (preferably three or four) ties must be measured with accuracies of 1 mm or better in each component, including any potential systematic effects. If this can be done, then the VLBI and GPS frames can be globally aligned to less than 1 mm in each Helmert component using our subset of nine ties. In any case, the X and Y rotations are better determined, to about 0.5 mm, due to the contribution of co-located polar motion. 相似文献
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北斗导航系统精密单点定位在地壳运动监测中的应用分析 总被引：1，自引：1，他引：0
主要基于7个台站观测到的BDS/GPS双模连续观测数据,时间跨度在2 a以上,利用武汉大学自主研发的PANDA软件的精密单点定位模式,对比分析了BDS/GPS双模观测数据的单系统定位精度,并探讨了BDS在地壳运动监测中的能力。通过对这些观测数据的解算及分析,结果表明,BDS在水平向的定位精度约为17 mm,垂向定位精度约为40 mm;GPS在水平向的定位精度要优于10 mm,垂向定位精度约为14 mm。基线统计结果显示,BDS检测弱信号的能力要低于GPS,但仍能够准确反映站点间基线长度和变化率特征。对比分析BDS和GPS得到的速度场,结果显示,两套速度场在水平向之间差值约为1~2 mm/a,且不存在系统性的差异。总体来看,虽然目前BDS精密单点定位精度要低于GPS,但是BDS目前仍可以用于监测形变量较大的地区地壳运动。 相似文献
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Ionospheric calibration of single frequency VLBI and GPS observations using dual GPS data 总被引：3，自引：1，他引：3
Summary The ionospheric effect is one of the main sources of error in Very Long Baseline Interferometry (VLBI) and Global Positioning System (GPS) high precision geodesy. Although the use of two frequencies allows the estimation of this effect, in some cases dual observations are not possible due to the available equipment or the type of observation. This paper presents the ionospheric calibration of single frequency VLBI and GPS observations based on the ionospheric electron content estimated from dual frequency GPS data. The ionospheric delays obtained with this procedure and the VLBI baseline length results have been compared with those obtained with dual frequency data. For the European geodetic VLBI baselines, both solutions agree at the 3–5 parts in 10–9 level. The noise introduced by the GPS-based calibration is in the order of 3 cm for the VLBI observables and of 10 cm for the GPS observables. 相似文献
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In recent years, ocean tide loading displacements (OTLD) have been measured using the Global Positioning System (GPS) and
Very Long Baseline Interferometry (VLBI). This study assesses the accuracy of GPS measurements of OTLD by comparison with
VLBI measurements and estimates derived from numerical ocean tide models. A daily precise point positioning (PPP) analysis
was carried out on ∼11 years of GPS data for each of 25 sites that have previous OTLD estimates based on data from co-located
VLBI sites. Ambiguities were fixed to integer values where possible. The resulting daily estimates of OTLD, at eight principal
diurnal and semi-diurnal tidal frequencies, were combined to give GPS measurements of OTLD at each site. The 3D GPS and VLBI
measurements of OTLD were compared with estimates computed (by convolution with Green’s functions) from five modern ocean
tide models (CSR4.0, FES2004, GOT00.2, NAO99b and TPXO6.2). The GPS/model agreement is shown to be similar to the VLBI/model
agreement. In the important radial direction, the GPS/model misfit is shown to be smaller than the VLBI/model misfit for seven
of the eight tidal constituents; the exception being the K2 constituent. Fixing of GPS carrier-phase ambiguities to integer
values resulted in a marginal improvement to the GPS/model agreement. Statistically, it is shown there is no significance
to the difference between the fit of the GPS and VLBI measurements of OTLD to modelled values. Equally, differences in fit
of either the complete set of GPS or VLBI estimates to the five sets of model-derived values cannot be identified with statistical
significance. It is thus concluded that, overall, we cannot distinguish between GPS and VLBI measurements of OTLD, and that
at the global scale, present ocean tide models are accurate to within the current measurement noise of these techniques. 相似文献
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H. Bâki Iz 《Journal of Geodesy》2006,80(5):259-269
In order to make successful earthquake predictions, detection and monitoring of baseline changes are important for investigating their origins, including precursory crustal deformations in tectonically active areas. In this study, differencing two baselines that run approximately parallel to each other and normal to the expected crustal deformations, and that share a station is proposed for analysis. Differencing reduces common systematic baseline errors, thereby enabling detection of subtle transient systematic changes in the baseline time-series that are otherwise buried in the measurement noise. Mean shift analysis, a well-known statistical technique to determine hether the mean of a stochastic process has shifted using cumulative sum charts, can then be used to locate the change points in the time-series. The application of this method to the differences of concurrently observed very long baseline interferometry (VLBI) and global positioning system (GPS) baselines in the Japanese Keystone project, where periodic and persistent baseline changes are removed, revealed transient variations in the baseline lengths several months prior to the seismic activity in the Izu Islands that started on June 26, 2000. Reproduction of the results using GPS and VLBI, two alternative baseline measurement techniques, validated the accuracy of the proposed approach for detecting previously hidden transient changes in the baseline lengths. 相似文献
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GGOS-D: homogeneous reprocessing and rigorous combination of space geodetic observations 总被引：3，自引：3，他引：0
M. Rothacher D. Angermann T. Artz W. Bosch H. Drewes M. Gerstl R. Kelm D. K?nig R. K?nig B. Meisel H. M��ller A. Nothnagel N. Panafidina B. Richter S. Rudenko W. Schwegmann M. Seitz P. Steigenberger S. Tesmer V. Tesmer D. Thaller 《Journal of Geodesy》2011,85(10):679-705
In preparation of activities planned for the realization of the Global Geodetic Observing System (GGOS), a group of German scientists has carried out a study under the acronym GGOS-D which closely resembles the ideas behind the GGOS initiative. The objective of the GGOS-D project was the investigation of the methodological and information-technological realization of a global geodetic-geophysical observing system and especially the integration and combination of the space geodetic observations. In the course of this project, highly consistent time series of GPS, VLBI, and SLR results were generated based on common state-of-the-art standards for modeling and parameterization. These series were then combined to consistently and accurately compute a Terrestrial Reference Frame (TRF). This TRF was subsequently used as the basis to produce time series of station coordinates, Earth orientation, and troposphere parameters. In this publication, we present results of processing algorithms and strategies for the integration of the space-geodetic observations which had been developed in the project GGOS-D serving as a prototype or a small and limited version of the data handling and processing part of a global geodetic observing system. From a comparison of the GGOS-D terrestrial reference frame results and the ITRF2005, the accuracy of the datum parameters is about 5?C7?mm for the positions and 1.0?C1.5?mm/year for the rates. The residuals of the station positions are about 3?mm and between 0.5 and 1.0?mm/year for the station velocities. Applying the GGOS-D TRF, the offset of the polar motion time series from GPS and VLBI is reduced to 50 ??as (equivalent to 1.5?mm at the Earth??s surface). With respect to troposphere parameter time series, the offset of the estimates of total zenith delays from co-located VLBI and GPS observations for most stations in this study is smaller than 1.5?mm. The combined polar motion components show a significantly better WRMS agreement with the IERS 05C04 series (96.0/96.0???as) than VLBI (109.0/100.7???as) or GPS (98.0/99.5???as) alone. The time series of the estimated parameters have not yet been combined and exploited to the extent that would be possible. However, the results presented here demonstrate that the experiences made by the GGOS-D project are very valuable for similar developments on an international level as part of the GGOS development. 相似文献