Earth rotation parameters estimation using satellite laser ranging measurements to multiple LEO satellites

2021 ◽  
Author(s):  
Hongmin Zhang ◽  
Keke Zhang ◽  
Yongqiang Yuan ◽  
Qian Zhang ◽  
Jiaqi Wu ◽  
...  
Keyword(s):  
Earth Rotation ◽  
Parameters Estimation ◽  
Laser Ranging ◽  
Step Method ◽  
Earth Rotation Parameters ◽  
Leo Satellites ◽  
One Step ◽  
Rotation Parameters ◽  
The Impact ◽  
Gps Observations

<p>Earth rotation parameters (ERP) are one of the key parameters in realization of the International Terrestrial Reference Frames (ITRF). Currently, the ERP products from International Laser Ranging Service (ILRS) are generated based on SLR observations to LAGEOS and Etalon satellites, which account for only about 9% of total SLR observations to Earth satellites. A large amount of SLR observations for the geodetic and oceanographic LEOs are neglected due to relatively degraded orbit caused by imperfect orbit models. However, thanks to the recent refinement of both dynamic and observation models, the quality of LEO orbits has been improved significantly, which makes it worthwhile to investigate the potential of these LEOs in the ERP estimation. In this study, we focus on the contribution of SLR observations from multiple LEO satellites to ERP estimation. The SLR observations of current seven LEO satellites (Swarm-A/B, GRACE-C/D, Sentinel-3A/B and Jason-3) as well as LAGEOS are used. Several strategies are designed to investigate the impact of the LEO orbit altitude, inclination and the number of LEO satellites. We also discuss the contribution of the application of ambiguity-fixed orbits and consider the simultaneous processing of SLR and GPS observations. The three-day solutions are selected and all the results are evaluated by the comparison with IERS Bulletin A.</p><p>The results show that for the single-LEO solutions, there is no evident relationship between the accuracy of ERP and the LEO orbit altitude and inclination. The best consistency with the IERS products is achieved by the Jason-3 solutions, with RMS values of 1.9mas, 1.8mas and 93us for X pole, Y pole and length of day (LOD) respectively. The multi-LEO solution results indicate that the accuracy of ERP can be improved gradually with the increase of LEO satellites. Compared with the single-LEO solution, the accuracy of X pole and Y pole of the 7-LEO solution is improved by 39.27% and 53.84% respectively. This result can be easily understood by the evident increase of SLR observations with the increase of LEO satellites. We also find the ERP estimation can benefit from the application of the ambiguity-fixed orbit.</p><p>In addition, apart from the solutions with LEO orbits fixed (two-step method), we also jointly process the onboard GPS observations and SLR measurements to obtain LEO orbits and ERP simultaneously (one-step method). The result indicates that the ERP of the one-step solution present a better accuracy than that of the two-step solution. Moreover, the LEO orbits can also benefit from the integrated processing.</p>

scholarly journals Earth Rotation Parameters Estimation Using GPS and SLR Measurements to Multiple LEO Satellites

2021 ◽  
Vol 13 (15) ◽  
pp. 3046
Author(s):  
Xingxing Li ◽  
Hongmin Zhang ◽  
Keke Zhang ◽  
Yongqiang Yuan ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Earth Rotation ◽  
Laser Ranging ◽  
Accuracy Improvement ◽  
Station Coordinates ◽  
Earth Rotation Parameters ◽  
Leo Satellites ◽  
One Step ◽  
Rotation Parameters ◽  
Gps Observations

Earth rotation parameters (ERP) are one of the key parameters in realization of the International Terrestrial Reference Frames (ITRF). At present, the International Laser Ranging Service (ILRS) generates the satellite laser ranging (SLR)-based ERP products only using SLR observations to Laser Geodynamics Satellite (LAGEOS) and Etalon satellites. Apart from these geodetic satellites, many low Earth orbit (LEO) satellites of Earth observation missions are also equipped with laser retroreflector arrays, and produce a large number of SLR observations, which are only used for orbit validation. In this study, we focus on the contribution of multiple LEO satellites to ERP estimation. The SLR and Global Positioning System (GPS) observations of the current seven LEO satellites (Swarm-A/B/C, Gravity Recovery and Climate Experiment (GRACE)-C/D, and Sentinel-3A/B) are used. Several schemes are designed to investigate the impact of LEO orbit improvement, the ERP quality of the single-LEO solutions, and the contribution of multiple LEO combinations. We find that ERP estimation using an ambiguity-fixed orbit can attain a better result than that using ambiguity-float orbit. The introduction of an ambiguity-fixed orbit contributes to an accuracy improvement of 0.5%, 1.1% and 15% for X pole, Y pole and station coordinates, respectively. In the multiple LEO satellite solutions, the quality of ERP and station coordinates can be improved gradually with the increase in the involved LEO satellites. The accuracy of X pole, Y pole and length-of-day (LOD) is improved by 57.5%, 57.6% and 43.8%, respectively, when the LEO number increases from three to seven. Moreover, the combination of multiple LEO satellites is able to weaken the orbit-related signal existing in the single-LEO solution. We also investigate the combination of LEO satellites and LAGEOS satellites in the ERP estimation. Compared to the LAGEOS solution, the combination leads to an accuracy improvement of 0.6445 ms, 0.6288 ms and 0.0276 ms for X pole, Y pole and LOD, respectively. In addition, we explore the feasibility of a one-step method, in which ERP and the orbit parameters are jointly determined, based on SLR and GPS observations, and present a detailed comparison between the one-step solution and two-step solution.

scholarly journals SLR Contribution to Investigation of Polar Motion

2000 ◽  
Vol 178 ◽  
pp. 267-276
Author(s):  
Zinovy Malkin
Keyword(s):  
Earth Rotation ◽  
Polar Motion ◽  
Satellite Laser Ranging ◽  
Laser Ranging ◽  
International Earth Rotation Service ◽  
Global Tracking ◽  
International Earth Rotation ◽  
Earth Rotation Parameters ◽  
Rotation Parameters

AbstractThe Satellite Laser Ranging (SLR) technique has been used to determine Earth Rotation Parameters (ERP) for over twenty years. Most of results contributed to the International Earth Rotation Service (IERS) are based on analysis of observations of Lageos 1 & 2 satellites collected by the global tracking network of about 40 stations. Now five analysis centers submit operational (with 2–15 days delay) solutions and about ten analysis centers contribute yearly final (up to 23 years) ERP series. Some statistics related to SLR observations and analysis are presented and analyzed. Possible problems in SLR observations and analysis and ways of its solution are discussed.

scholarly journals Combination of Earth Rotation Parameters Obtained in 1980 by Various Techniques

1981 ◽  
Vol 63 ◽  
pp. 2-10
Author(s):  
Martine Feissel
Keyword(s):  
Earth Rotation ◽  
Laser Ranging ◽  
Radio Interferometry ◽  
Lunar Laser Ranging ◽  
Lunar Laser ◽  
Earth Rotation Parameters ◽  
Rotation Parameters

AbstractIn 1980, Earth rotation parameters have been measured by classical astrometry, Doppler and laser satellite techniques, Lunar Laser Ranging and radio-interferometry. The precision of the series and their systematic differences are investigated; a combination algorithm is applied to the series available throughout the year.

scholarly journals Is Lunar Ranging a Viable Component in a Next-Generation Earth Rotation Service?

1979 ◽  
Vol 82 ◽  
pp. 257-260 ◽  
Author(s):  
J. Derral Mulholland
Keyword(s):  
Earth Rotation ◽  
Laser Ranging ◽  
Next Generation ◽  
Lunar Laser Ranging ◽  
New Techniques ◽  
Lunar Laser ◽  
Earth Rotation Parameters ◽  
New Space ◽  
Rotation Parameters

Several new “space” techniques have been used for episodic determination of Earth rotation parameters, usually the variation in apparent longitude (UT0) and apparent latitude of an observing station. Earth rotation services require more than episodic determinations; they need near-daily determinations. Since 1975, planning has been underway for a demonstration of the viability of lunar laser ranging for such a usage. The observing campaign named Earth Rotation from Lunar Distances (EROLD) was organized with the proposed activity to cover the years 1977–78. Progress has not been so rapid as hoped, but it remains true that lunar ranging has produced more Earth rotation information than other new techniques.

Combination of GNSS and VLBI data for consistent estimation of Earth Rotation Parameters

2021 ◽  
Author(s):  
Lisa Lengert ◽  
Claudia Flohrer ◽  
Anastasiia Girdiuk ◽  
Hendrik Hellmers ◽  
Daniela Thaller
Keyword(s):  
Time Series ◽  
Earth Rotation ◽  
Polar Motion ◽  
Normal Equation ◽  
Station Coordinates ◽  
Earth Rotation Parameters ◽  
Vlbi Data ◽  
Rotation Parameters ◽  
Gnss Data ◽  
The Impact

<p>We present the current activities of the Federal Agency for Cartography and Geodesy (BKG) towards a combined processing of VLBI and GNSS data.  The main goal of the combined analyses of the two different space-geodetic techniques is the improvement of the consistency between the techniques through common parameters, i.e., mainly Earth Rotation Parameters (ERPs), but also station coordinates and tropospheric parameters through local ties and atmospheric ties, respectively.</p><p>Based on our previous combination studies using GNSS data and VLBI Intensive sessions on a daily and multi-day level, we generate a consistent, low-latency ERP time series with a regular daily resolution for polar motion and dUT1. We achieved in this way a significant accuracy improvement of the dUT1 time series and a slight improvement of the pole coordinates time series, comparing ERPs from the combined processing with the individual technique-specific ERPs.</p><p>In our recent studies, we extend the combination of GNSS and VLBI Intensive sessions by adding VLBI 24-hour sessions in order to exploit the benefit of the combination to its maximum extend. We analyse the impact of the combination on the global parameters of interest, i.e., mainly dUT1, polar motion and LOD, but also on station coordinates.</p><p>BKG’s primary interest is the combination of GNSS and VLBI data on the observation level. However, the current combination efforts are based on the normal equation level using technique-specific SINEX files as a starting point.</p>

scholarly journals Combination of VLBI Intensive Sessions with GNSS for generating Low latency Earth Rotation Parameters

2019 ◽  
Vol 50 ◽  
pp. 49-56
Author(s):  
Hendrik Hellmers ◽  
Daniela Thaller ◽  
Mathis Bloßfeld ◽  
Alexander Kehm ◽  
Anastasiia Girdiuk
Keyword(s):  
Time Series ◽  
Earth Rotation ◽  
Normal Equation ◽  
Laser Ranging ◽  
Low Latency ◽  
Lunar Laser Ranging ◽  
Earth Orientation ◽  
The Earth ◽  
Earth Rotation Parameters ◽  
Rotation Parameters

Abstract. The Earth Orientation Parameters (EOPs) are published by the Earth Orientation Centre of the International Earth Rotation and Reference Systems Service (IERS). They are provided as the low-latency Bulletin A and the 30 d latency long-term EOP time series IERS 14 C04. The EOPs are a combined product derived from different geodetic space techniques, namely Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) and Very Long Baseline Interferometry (VLBI). Since not all techniques are equally sensitive to every EOP, several parameters rely on specific observation techniques. As an example, dUT1 can only be estimated from VLBI observations. This means VLBI is an essential part of the estimation procedure for consistent EOPs. Within this paper, we are performing a combination of two low-latency space geodetic techniques as they enable the estimation of the full set of Earth Rotation Parameters (ERPs; polar motion, dUT1 and the corresponding rates). In particular, we focus on the development of a robust combination scheme of 1 h VLBI Intensive sessions with so-called GNSS Rapid solutions on the normal equation level of the Gauß-Markov model. The aim of the study is to provide highly accurate low-latency ERPs. So far, a latency of approximately only 1–3 d cold be reached since the main limiting factor is still the latency of the input data. The mathematical background of the applied algorithm is discussed in detail and evaluated by numerical results of empirical investigations. The combination yields a numerical stabilization of the equation system as well as an improvement (reduction) of the corresponding root mean square deviation of the epoch-wise estimated parameters w.r.t. the IERS 14 C04 reference time series.

scholarly journals Determination of earth rotation and station coordinates from Lageos data

1988 ◽  
Vol 128 ◽  
pp. 141-146
Author(s):  
A. T. Sinclair ◽  
G. M. Appleby ◽  
J. Y. Xia
Keyword(s):  
Earth Rotation ◽  
Laser Ranging ◽  
Royal Greenwich Observatory ◽  
Absolute Value ◽  
The Earth ◽  
Station Coordinates ◽  
Earth Rotation Parameters ◽  
Rotation Parameters ◽  
Short Arc

A package of computer programs for the analysis of satellite laser ranging data has been written at the Royal Greenwich Observatory. The methods used are described, and the Earth rotation parameters and station coordinates derived from the MERIT Lageos data are given, with comparisons with other determinations. The uncertainty of the absolute value of the z-coordinate of the stations is discussed, and a method of short-arc analysis for determining baselines is described.

On the potential of single-satellite space ties to achieve the Global Geodetic Observing System goals

2021 ◽  
Author(s):  
Patrick Schreiner ◽  
Nicat Mammadaliyev ◽  
Susanne Glaser ◽  
Rolf König ◽  
Karl Hans Neumayer ◽  
...  
Keyword(s):  
Earth Rotation ◽  
Research Collaboration ◽  
Precise Orbit Determination ◽  
Added Value ◽  
Station Coordinates ◽  
Earth Rotation Parameters ◽  
German Research ◽  
Rotation Parameters ◽  
The Impact ◽  
Space Ties

<p>GGOS-SIM-2, funded by the German Research Foundation (DFG), is a research collaboration project between the German Research Center for Geosciences (GFZ) and the Technische Universität Berlin (TUB). Simulations are utilized to examine the potential of co-location in space, called space ties, of the four main space geodetic techniques, i.e. DORIS, GNSS, SLR and VLBI to achieve the requirements of the Global Geodetic Observing System (GGOS) for a global terrestrial reference frame (TRF), 1 mm accuracy and 1 mm / decade long-term stability. The simulations are performed for six fictional orbit scenarios, including proposed missions GRASP (USA) and E-GRASP (EU), and expanded by a variation of the E-GRASP orbit with lower eccentricity as well as three higher orbiting circular orbits with different inclination over a time span of seven years. For most realistic simulations, we first evaluated real DORIS, GPS and SLR observations to the satellites LAGEOS 1 und 2, Ajisai, LARES, Starlette, Stella, ENVISAT, Jason 1 und 2, Sentinel 3A and B using Precise Orbit Determination (POD), to get detailed information about the individual station and receiver accuracy, availability and further technique-specific effects. Then, we generate simulated single-technique TRF solutions based on existing missions and add the co-location-in-space satellite in the six orbit scenarios. In order to quantify the effects of the different scenarios, we examine the added value w.r.t. the existing missions in terms of origin and scale and of formal errors of the station coordinates and Earth rotation parameters. We also investigate the impact of systematic errors on the derived orbits on the final TRF. The different techniques show individual advantages regarding the respective orbit parameters. For instance, a higher eccentricity of the orbit seems to lead to improved accuracy of length-of-day (LOD) from SLR. The results will help to find the best trade-off for a satellite that co-locates all four techniques in space towards a GGOS-compliant TRF and Earth rotation parameters.</p>

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