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1.
ITRF2014是地球参考系的最新实现。该框架利用正弦函数估计负荷对台站位置的季节性效应,与ITRF2008相比,可以得到更稳定、精确的速度场;另外,ITRF2014引入了震后形变模型,可以更好地分析测站的非线性运动。本文通过分析发现:ITRF2014其原点相较于ITRF2008,其符合精度为3.5 mm;两种技术(VLBI和SLR)在2010.0历元确定的尺度因子不符值为1.18 ppb;同时,局部测量解与空间大地测量解解算的本地连接向量仍存在较大不符。 相似文献
2.
The 2008 DGFI realization of the ITRS: DTRF2008 总被引：11，自引：11，他引：0
Manuela Seitz Detlef Angermann Mathis Blo?feld Hermann Drewes Michael Gerstl 《Journal of Geodesy》2012,86(12):1097-1123
A new realization of the International Terrestrial System was computed at the ITRS Combination Centre at DGFI as a contribution to ITRF2008. The solution is labelled DTRF2008. In the same way as in the DGFI computation for ITRF2005 it is based on either normal equation systems or estimated parameters derived from VLBI, SLR, GPS and DORIS observations by weekly or session-wise processing. The parameter space of the ITRS realization comprises station positions and velocities and daily resolved Earth Orientation Parameters (EOP), whereby for the first time also nutation parameters are included. The advantage of starting from time series of input data is that the temporal behaviour of geophysical parameters can be investigated to decide whether the parameters can contribute to the datum realization of the ITRF. In the same way, a standardized analysis of station position time series can be performed to detect and remove discontinuities. The advantage of including EOP in the ITRS realization is twofold: (1) the combination of the coordinates of the terrestrial pole—estimated from all contributing techniques—links the technique networks in two components of the orientation, leading to an improvement of consistency of the Terrestrial Reference Frame (TRF) and (2) in their capacity as parameters common to all techniques, the terrestrial pole coordinates enhance the selection of local ties as they provide a measure for the consistency of the combined frame. The computation strategy of DGFI is based on the combination of normal equation systems while at the ITRS Combination Centre at IGN solutions are combined. The two independent ITRS realizations provide the possibility to assess the accuracy of ITRF by comparison of the two frames. The accuracy evaluation was done separately for the datum parameters (origin, orientation and scale) and the network geometry. The accuracy of the datum parameters, assessed from the comparison of DTRF2008 and ITRF2008, is between 2–5?mm and 0.1–0.8?mm/year depending on the technique. The network geometry (station positions and velocities) agrees within 3.2?mm and 1.0?mm/year. A comparison of DTRF2008 and ITRF2005 provides similar results for the datum parameters, but there are larger differences for the network geometry. The internal accuracy of DTRF2008—that means the level of conservation of datum information and network geometry within the combination—was derived from comparisons with the technique-only multi-year solutions. From this an internal accuracy of 0.32?mm for the VLBI up to 3.3?mm for the DORIS part of the network is found. The internal accuracy of velocities ranges from 0.05?mm/year for VLBI to 0.83?mm/year for DORIS. The internal consistency of DTRF2008 for orientation can be derived from the analysis of the terrestrial pole coordinates. It is estimated at 1.5–2.5?mm for the GPS, VLBI and SLR parts of the network. The consistency of these three and the DORIS network part is within 6.5?mm. 相似文献
3.
Xavier Collilieux Laurent Métivier Zuheir Altamimi Tonie van Dam Jim Ray 《GPS Solutions》2011,15(3):219-231
The International GNSS Service (IGS) contributes to the construction of the International Terrestrial Reference Frame (ITRF)
by submitting time series of station positions and Earth Rotation Parameters (ERP). For the first time, its submission to
the ITRF2008 construction is based on a combination of entirely reprocessed GPS solutions delivered by 11 Analysis Centers
(ACs). We analyze the IGS submission and four of the individual AC contributions in terms of the GNSS frame origin and scale,
station position repeatability and time series seasonal variations. We show here that the GPS Terrestrial Reference Frame
(TRF) origin is consistent with Satellite laser Ranging (SLR) at the centimeter level with a drift lower than 1 mm/year. Although
the scale drift compared to Very Long baseline Interferometry (VLBI) and SLR mean scale is smaller than 0.4 mm/year, we think
that it would be premature to use that information in the ITRF scale definition due to its strong dependence on the GPS satellite
and ground antenna phase center variations. The new position time series also show a better repeatability compared to past
IGS combined products and their annual variations are shown to be more consistent with loading models. The comparison of GPS
station positions and velocities to those of VLBI via local ties in co-located sites demonstrates that the IGS reprocessed
solution submitted to the ITRF2008 is more reliable and precise than any of the past submissions. However, we show that some
of the remaining inconsistencies between GPS and VLBI positioning may be caused by uncalibrated GNSS radomes. 相似文献
4.
VLBI terrestrial reference frame contributions to ITRF2008 总被引：6，自引：5，他引：1
In late 2008, the Product Center for the International Terrestrial Reference Frame (ITRF) of the International Earth Rotation
and Reference Systems Service (IERS) issued a call for contributions to the next realization of the International Terrestrial
Reference System, ITRF2008. The official contribution of the International VLBI Service for Geodesy and Astrometry (IVS) to
ITRF2008 consists of session-wise datum-free normal equations of altogether 4,539 daily Very Long Baseline Interferometry
(VLBI) sessions from 1979.7 to 2009.0 including data of 115 different VLBI sites. It is the result of a combination of individual
series of session-wise datum-free normal equations provided by seven analysis centers (ACs) of the IVS. All series are completely
reprocessed following homogeneous analysis options according to the IERS Conventions 2003 and IVS Analysis Conventions. Altogether,
nine IVS ACs analyzed the full history of VLBI observations with four different software packages. Unfortunately, the contributions
of two ACs, Institute of Applied Astronomy (IAA) and Geoscience Australia (AUS), had to be excluded from the combination process.
This was mostly done because the IAA series exhibits a clear scale offset while the solution computed from normal equations
contained in the AUS SINEX files yielded unreliable results. Based on the experience gathered since the combination efforts
for ITRF2005, some discrepancies between the individual series were discovered and overcome. Thus, the consistency of the
individual VLBI solutions has improved considerably. The agreement in terms of WRMS of the Terrestrial Reference Frame (TRF)
horizontal components is 1 mm, of the height component 2 mm. Comparisons between ITRF2005 and the combined TRF solution for
ITRF2008 yielded systematic height differences of up to 5 mm with a zonal signature. These differences can be related to a
pole tide correction referenced to a zero mean pole used by four of five IVS ACs in the ITRF2005 contribution instead of a
linear mean pole path as recommended in the IERS Conventions. Furthermore, these systematics are the reason for an offset
in the scale of 0.4 ppb between the IVS’ contribution to ITRF2008 and ITRF2005. The Earth orientation parameters of seven
series used as input for the IVS combined series are consistent to a huge amount with about 50 μas WRMS in polar motion and
3 μs in dUT1. 相似文献
5.
IGS contribution to the ITRF 总被引：2，自引：0，他引：2
We examine the contribution of the International GNSS Service (IGS) to the International Terrestrial Reference Frame (ITRF) by evaluating the quality of the incorporated solutions as well as their major role in the ITRF formation. Starting with the ITRF2005, the ITRF is constructed with input data in the form of time series of station positions (weekly for satellite techniques and daily for VLBI) and daily Earth Orientation Parameters. Analysis of time series of station positions is a fundamental first step in the ITRF elaboration, allowing to assess not only the stations behavior, but also the frame parameters and in particular the physical ones, namely the origin and the scale. As it will be seen, given the poor number and distribution of SLR and VLBI co-location sites, the IGS GPS network plays a major role by connecting these two techniques together, given their relevance for the definition of the origin and the scale of the ITRF. Time series analysis of the IGS weekly combined and other individual Analysis Center solutions indicates an internal precision (or repeatability) <2 mm in the horizontal component and <5 mm in the vertical component. Analysis of three AC weekly solutions shows generally poor agreement in origin and scale, with some indication of better agreement when the IGS started to use the absolute model of antenna phase center variations after the GPS week 1400 (November 2006). 相似文献
6.
7.
We examined the sensitivity of estimates of global sea-level rise obtained from GPS-corrected long term tide gauge records to uncertainties in the International Terrestrial Reference Frame (ITRF) realization. A useful transfer function was established, linking potential errors in the reference frame datum (origin and scale) to resulting errors in the estimate of global sea level rise. Contrary to scale errors that are propagated by a factor of 100%, the impact of errors in the origin depends on the network geometry. The geometry of the network analyzed here resulted in an error propagation factor of 50% for the Z component of the origin, mainly due to the asymmetry in the distribution of the stations between hemispheres. This factor decreased from 50% to less than 10% as the geometry of the network improved using realistic potential stations that did not yet meet the selection criteria (e.g., record length, data availability). Conversely, we explored new constraints on the reference frame by considering forward calculations involving tide gauge records. A reference frame could be found in which the scatter of the regional sea-level rates was limited. The resulting reference frame drifted by 1.36 ± 0.22? mm/year from the ITRF2000 origin in the Z component and by ?0.44 ± 0.22?mm/year from the ITRF2005 origin. A bound on the rate of global sea level rise of 1.2 to 1.6?mm/year was derived for the past century, depending on the origin of the adopted reference frame. The upper bound is slightly lower than previous estimates of 1.8?mm/year discussed in the IPCC fourth report. 相似文献
8.
Evaluation of the ITRF2008 GPS vertical velocities using satellite antenna z-offsets 总被引：2，自引：0，他引：2
We develop a method to evaluate the terrestrial reference frame (TRF) scale rate error using Global Positioning System (GPS) satellite antenna phase center offset (APCO) parameters and apply it to ITRF2008. We search for the TRF in which z-APCO parameters have the smallest drift. In order to provide realistic error bars for the z-APCO drifts, we pay attention to model periodic variations and auto-correlated noise processes in the z-APCO time series. We will show that the GPS scale rate with respect to a frame is, as a first approximation, proportional to the estimated mean z-APCO trend if that frame is used to constrain station positions. Thus, an ITRF2008 scale rate error between ?0.27 and ?0.06 mm/yr depending on the GPS analysis center can be estimated, which demonstrates the high quality of the newly constructed ITRF2008. We will also demonstrate that the traditional estimates of the GPS scale rate from 7-parameter similarity transformations are consistent with our newly derived GPS scale rates with respect to ITRF2008 within two sigmas. We find using International GNSS Service (IGS) products that the traditional approach is relevant for scale rate determination even if some of the z-APCO values supplied by the IGS were not simultaneously calibrated. As the scale rate is related to the accuracy of vertical velocities, our estimates supply a conservative evaluation that can be used for error budget computation. 相似文献
9.
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
10.
We examine the contribution of the Doppler Orbit determination and Radiopositioning Integrated by Satellite (DORIS) technique to the International Terrestrial Reference Frame (ITRF2005) by evaluating the quality of the submitted solutions as well as that of the frame parameters, especially the origin and the scale. Unlike the previous versions of the ITRF, ITRF2005 is constructed with input data in the form of time-series of station positions (weekly for satellite techniques and daily for VLBI) and daily Earth orientation parameters (EOPs), including full variance–covariance information. Analysis of the DORIS station positions’ time-series indicates an internal precision reaching 15 mm or better, at a weekly sampling. A cumulative solution using 12 years of weekly time-series was obtained and compared to a similar International GNSS Service (IGS) GPS solution (at 37 co-located sites) yielding a weighted root mean scatter (WRMS) of the order of 8 mm in position (at the epoch of minimum variance) and about 2.5 mm/year in velocity. The quality of this cumulative solution resulting from the combination of two individual DORIS solutions is better than any individual solution. A quality assessment of polar motion embedded in the contributed DORIS solutions is performed by comparison with the results of other space-geodetic techniques and in particular GPS. The inferred WRMS of polar motion varies significantly from one DORIS solution to another and is between 0.5 and 2 mas, depending on the strategy used and in particular estimating or not polar motion rate by the analysis centers. This particular aspect certainly needs more investigation by the DORIS Analysis Centers. 相似文献
11.
基于全球板块运动模型分析大西洋扩张变化 总被引：1，自引：0，他引：1
基于现代空间测量技术SLR、VLBI和GPS实测资料，解算出大西洋中脊海底扩张速率，其中北大西洋的东西向扩张速率平均为35mm/a，赤道大西洋东西向扩张速度分别为20－25mm/a，南大西洋东西向扩张速率为22－28mm/a，证实全球板块运动的存在及大西洋扩张学说，并基于全球几百万年地质模型NNR－NUVEL1A，北大西洋的东西向扩张速率平均为24．3mm/a，基于最新全球板块运动模型ITRF2000VEL，北大西洋的东西向扩张速率平均为20．8mm/a，总体上大西洋实测东西扩张速度与根据地学资料推出的地球板块运动模型和最新ITRF2000VEL模型的结果基本一致。 相似文献
12.
ITRF2000和新的全球板块运动模型 总被引：6，自引：0，他引：6
地学工作者一直关注的ITRF2000地球参考框架初步结果已于2001年3月19日公布，ITRF2000综合了VLBI、SLR，LLR，GPS和DORIS技术，产生736个点位坐标和54个核心站，文中介绍了ITRF2000，并利用ITRF2000综合解的结果计算全球板块的欧拉矢量，建立了基于空间实测数据基础 的最新全球板块运动模型。 相似文献
13.
当前地震、地质灾害等现象的频繁发生,表明对于地壳运动尤其是垂直方向的研究是迫切而必需的,而研究垂直地壳运动的一个重要前提就是其参考基准的确立。针对目前国内外对于全球垂直地壳运动参考基准不统一的现状,分析了研究全球统一的垂直地壳运动参考基准的必要性,提出将ITRF2008框架下获取的SLR的垂向速度场作为全球垂直地壳运动参考基准的方案,论证了该方案的合理性,并利用GPS和VLBI的观测数据,求取了其速度场与SLR垂直基准之间的系统差,分析了产生不同大小且方向各异系统差的原因,实现了各速度场与全球垂直地壳运动参考基准的统一。由于该基准包含了较为丰富的地球物理信息,具有可发展、可提高以及直接相对于地球质心等特性,因此,我们推荐将ITRF2008框架下SLR技术获取的垂向速度场定义为全球垂直地壳运动的参考基准。 相似文献
14.
In geodetic and geophysical applications of GPS, it is important to realize the ephemerides of the GPS satellites and the coordinates of station positions in a consistent reference system. At present, more than one reference system is being used by various GPS users depending on their specific applications. The WGS-84 and various reference frames based on satellite laser ranging (SLR), very long baseline interferometry (VLBI), or a combination of SLR and VLBI are the most commonly used in high precision geophysical applications. The WGS-84 is widely used in applications which rely on the GPS broadcast ephemeris. Station coordinates estimated in one system may have to be transformed to another for further use or for evaluation/comparison purposes. This paper presents a seven-parameter transformation between the WGS-84 and SLR/VLBI reference frames. The GPS double-differenced phase measurements for two consecutive weeks from a set of five Defense Mapping Agency (DMA) sites (defined in the WGS-84 frame) and from an augmented set of fifteen CIGNET sites (defined in the SLR/VLBI frame) were processed in a least squares estimation scheme to determine station coordinates, from which the transformation parameters were determined. A scale difference of about 0.2 ppm and an orientation difference in longitude of about 31 milliarcseconds were found to be the only parameters of significance between the adopted SLR/VLBI and the WGS-84 frames. Transformation between WGS-84 and the ITRF90 is also included, in which the scale difference is the same as before but the longitude rotation is about 16 mas. 相似文献
15.
Susanne Glaser Rolf König Dimitrios Ampatzidis Tobias Nilsson Robert Heinkelmann Frank Flechtner Harald Schuh 《Journal of Geodesy》2017,91(7):723-733
In this study, we assess the impact of two combination strategies, namely local ties (LT) and global ties (GT), on the datum realization of Global Terrestrial Reference Frames in view of the Global Geodetic Observing System requiring 1 mm-accuracy. Simulated Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) data over a 7 year time span was used. The LT results show that the geodetic datum can be best transferred if the precision of the LT is at least 1 mm. Investigating different numbers of LT, the lack of co-located sites on the southern hemisphere is evidenced by differences of 9 mm in translation and rotation compared to the solution using all available LT. For the GT, the combination applying all Earth rotation parameters (ERP), such as pole coordinates and UT1-UTC, indicates that the rotation around the Z axis cannot be adequately transferred from VLBI to SLR within the combination. Applying exclusively the pole coordinates as GT, we show that the datum can be transferred with mm-accuracy within the combination. Furthermore, adding artificial stations in Tahiti and Nigeria to the current VLBI network results in an improvement in station positions by 13 and 12%, respectively, and in ERP by 17 and 11%, respectively. Extending to every day VLBI observations leads to 65% better ERP estimates compared to usual twice-weekly VLBI observations. 相似文献
16.
The paper presents the results of crustal deformation, as evidenced by changed station coordinates, in the Tokyo metropolitan area detected by the satellite laser ranging (SLR) technique. The coordinates of two Key Stone SLR stations, Tateyama and Kashima, were determined from 4 weeks of orbital arcs of the LAGEOS-1 and LAGEOS-2 satellites with respect to 16 SLR stations kept fixed in the ITRF2000 reference frame. The station coordinates were calculated using the NASA GEODYN-II orbital program. The orbital RMS-of-fit for both satellites was 16 mm. The standard deviation of the estimated positions was 3 mm. A jump of about 5 cm in the baseline length between the Kashima and Tateyama stations was detected in June–August 2000 by VLBI and GPS techniques. This work confirms this crustal deformation as determined by SLR and vice versa. Analysis of coordinates of these stations shows that this effect was caused by a 4.5-cm displacement of the Tateyama station in the north-east direction. The change in the vertical component was not significant. 相似文献
17.
从全球国际地球参考框架（International Terrestrial Reference Frame，ITRF）的建立、维护与发展，卫星测高、卫星重力等的发展及应用，全球卫星导航系统（Global Navigation Satellite System，GNSS）、卫星激光测距（Satellite Laser Ranging，SLR）、甚长基线干涉测量（very Long Baseline Interferometry，VLBI）、卫星多普勒定轨定位（Doppler Orbitography by Radiopositioning Integrated on Satellite，DORIS）的融合应用，海洋测绘和室内定位的发展等几个方面综述了大地测量学及卫星导航定位技术的最新进展，并提出中国2000国家大地坐标系与自主卫星导航系统的主要应用及发展目标。 相似文献
18.
The contribution of the International VLBI Service for Geodesy and Astrometry (IVS) to the ITRF2005 (International Terrestrial
Reference Frame 2005) has been computed by the IVS Analysis Coordinator’s office at the Geodetic Institute of the University
of Bonn, Germany. For this purpose the IVS Analysis Centres (ACs) provided datum-free normal equation matrices in Solution
INdependent EXchange (SINEX) format for each 24 h observing session to be combined on a session-by-session basis by a stacking
procedure. In this process, common sets of parameters, transformed to identical reference epochs and a prioris, and especially representative relative weights have been taken into account for each session. In order to assess the quality
of the combined IVS files, Earth orientation parameters (EOPs) and scaling factors have been derived from the combined normal
equation matrices. The agreement of the EOPs of the combined normal equation matrices with those of the individual ACs in
terms of weighted root mean square (WRMS) is in the range of 50–60 μas for the two polar motion components and about 3 μs
for UT1−UTC. External comparisons with International GNSS Serive (IGS) polar motion components is at the level of 130–170 μas
and 21 μs/day for length of day (LOD). The scale of the terrestrial reference frame realized through the IVS SINEX files agrees
with ITRF2000 at the level of 0.2 ppb. 相似文献
19.
20.
The conventional international origin (CIO), established from observations made a century ago, is not directly related to observations by modern space-geodetic techniques. Both the greater precision of these techniques and improved knowledge of the structure of the Earth justify the need for a new CIO. We analyze recent polar motion time-series (VLBI, SLR, and GPS) to test estimators that might be used to establish such a new conventional origin. This new origin would be defined as the barycenter of the motion of the pole for a specific epoch. Consistency among the series examined is of the order of 2 milli-arc-seconds. A drift model can be employed in the analysis of specific series to establish an origin as the barycenter at a specific epoch, rather than the midpoint of the series. As an example, we estimate a “Conventional International Reference Origin” for the year 2000.0, using polar motion series that began in 1984. 相似文献