Network Effects and Handling of the Geocenter Motion in Multi‐GNSS Processing

Zajdel, Radosław; Sośnica, Krzysztof; Dach, Rolf; Bury, Grzegorz; Prange, Lars; Jäggi, Adrian

doi:10.1029/2019jb017443

Cited by 30 publications

(34 citation statements)

References 46 publications

(81 reference statements)

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“…The IQR of differences are greater than 60 and 80 µas for the X and Y pole coordinate, respectively. These results are higher than those indicated by Ray et al (2017) and Zajdel et al (2019) for GNSS solutions. The large differences confirm the presumption that in the case of an inhomogeneously distributed set of the datum-defining stations the ERPs are strongly affected.…”

Section: Impact On Earth Rotation Parameterscontrasting

confidence: 69%

“…Couhert et al (2018) indicated almost a 5 mm shift along with the X component of the GCC between SLR and DORIS solutions. On the other hand, Zajdel et al (2019) found a network effect revealing a shift of 4 mm in the origin along the Y-axis between GNSS and SLR solutions. The estimation of the reliable GCC from SLR is crucial to deliver information about the mass change in the system Earth to the other techniques which are less sensitive to the geocenter motion, i.e., satellite altimetry, GNSS, or to support the GRACE-derived gravity field variations (Baur et al 2013).…”

Section: Impact On the Geocenter Coordinatesmentioning

confidence: 96%

“…In principle, the CoM would be also available in GNSS and DORIS. However, due to the accumulated impact of technique-specific errors and model uncertainties both are able to access 'apparent CoM' rather than the true CoM (Bloßfeld et al 2014;Zajdel et al 2019; Rebischung and Garayt 2013).…”

Section: Origin Of the Terrestrial Reference Framementioning

confidence: 99%

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Impact of network constraining on the terrestrial reference frame realization based on SLR observations to LAGEOS

Zajdel

Sośnica

Drożdżewski

et al. 2019

J Geod

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The Satellite Laser Ranging (SLR) network struggles with some major limitations including an inhomogeneous global station distribution and uneven performance of SLR sites. The International Laser Ranging Service (ILRS) prepares the time-variable list of the most well-performing stations denoted as 'core sites' and recommends using them for the terrestrial reference frame (TRF) datum realization in SLR processing. Here, we check how different approaches of the TRF datum realization using minimum constraint conditions (MCs) and the selection of datum-defining stations affect the estimated SLR station coordinates, the terrestrial scale, Earth rotation parameters (ERPs), and geocenter coordinates (GCC). The analyses are based on the processing of the SLR observations to LAGEOS-1/-2 collected between 2010 and 2018. We show that it is essential to reject outlying stations from the reference frame realization to maintain a high quality of SLR-based products. We test station selection criteria based on the Helmert transformation of the network w.r.t. the a priori SLRF2014 coordinates to reject misbehaving stations from the list of datum-defining stations. The 25 mm threshold is optimal to eliminate the epoch-wise temporal deviations and to provide a proper number of datum-defining stations. According to the station selection algorithm, we found that some of the stations that are not included in the list of ILRS core sites could be taken into account as potential core stations in the TRF datum realization. When using a robust station selection for the datum definition, we can improve the station coordinate repeatability by 8%, 4%, and 6%, for the North, East and Up components, respectively. The global distribution of datum-defining stations is also crucial for the estimation of ERPs and GCC. When excluding just two core stations from the SLR network, the amplitude of the annual signal in the GCC estimates is changed by up to 2.2 mm, and the noise of the estimated pole coordinates is substantially increased.

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Section: Impact On Earth Rotation Parameterscontrasting

confidence: 69%

Section: Impact On the Geocenter Coordinatesmentioning

confidence: 96%

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Impact of network constraining on the terrestrial reference frame realization based on SLR observations to LAGEOS

Zajdel

Sośnica

Drożdżewski

et al. 2019

J Geod

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“…GNSS observation processing is consistent with Zajdel et al (2019) and Bury et al (2019). We estimated a 1-day orbital arc integrating the orbits within 5-minute intervals.…”

Section: Orbit Determination Strategiesmentioning

confidence: 84%

Toward the 1-cm Galileo orbits: challenges in modeling of perturbing forces

Bury

Sośnica

Zajdel

et al. 2020

J Geod

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Precise orbit determination demands knowledge of perturbing forces acting on the satellites of the Global Navigation Satellite Systems (GNSS). The metadata published by the European GNSS Agency for the Galileo satellites allow for the composition of the analytical box-wing model dedicated for coping with the direct solar radiation pressure (SRP), albedo, and infrared radiation (IR). Based on the box-wing model, we evaluated both the magnitude and the characteristic periods of accelerations caused by all the aforementioned forces. We assess which perturbations can be absorbed by the extended Empirical CODE Orbit Model (ECOM2) and what are the consequences of neglecting higher-order ECOM2 coefficients. In order to evaluate the impact of SRP, albedo, IR, and the navigation antenna thrust, we perform a series of precise Galileo orbit determination strategies for Galileo In-Orbit-Validation (IOV), Full Operational Capability (FOC), and two FOC satellites launched into eccentric orbits. The proposed box-wing model is capable of absorbing approximately 97% of the SRP in the Sun-satellite direction, whereas the rest can be mitigated by an additionally estimated small set of empirical parameters. The purely physical box-wing model does not fully handle satellite misorientation and re-radiation effects, such as Y -bias, solar panel rotation lag, that is the misalignment causing a constant acceleration perpendicular to the solar panel axis and the direction to the Sun. However, the box-wing model is especially crucial in terms of the absorption of the higher-order terms of SRP and stabilizes the orbit solutions during the eclipsing periods. Based on the SLR residual analysis, we found a systematic effect at the level up to 50 mm resulting from the omission of the high-order empirical orbit coefficients. We also found that the impact of the albedo, IR, and transmitter antenna thrust on the Galileo orbits reach the level of 5, 14, and 20 mm, respectively. Eventually, we obtain the overall accuracy of the Galileo-FOC orbits at the level of 22.5 mm, even for the eclipsing period for the solution which considers the box-wing model with the estimation of the constant empirical accelerations.

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“…Sośnica et al studied different orbit parameterizations, particularly different arc lengths and the impact of pseudo-stochastic pulses and dynamical orbit parameters on the quality of solutions for LEO satellites [22]. Now, pseudo-stochastic pulses are typically used by the Center for Orbit Determination in Europe (CODE) for precise GNSS orbit determination for unmaneuvered satellites [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Precise Orbit Determination for BeiDou GEO/IGSO Satellites during Orbit Maneuvering with Pseudo-Stochastic Pulses

et al. 2019

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In order to provide better service for the Asia-Pacific region, the BeiDou navigation satellite system (BDS) is designed as a constellation containing medium earth orbit (MEO), geostationary earth orbit (GEO), and inclined geosynchronous orbit (IGSO). However, the multi-orbit configuration brings great challenges for orbit determination. When orbit maneuvering, the orbital elements of the maneuvered satellites from broadcast ephemeris are unusable for several hours, which makes it difficult to estimate the initial orbit in the process of precise orbit determination. In addition, the maneuvered force information is unknown, which brings systematic orbit integral errors. In order to avoid these errors, observation data are removed from the iterative adjustment. For the above reasons, the precise orbit products of maneuvered satellites are missing from IGS (international GNSS (Global Navigation Satellite System) service) and iGMAS (international GNSS monitoring and assessment system). This study proposes a method to determine the precise orbits of maneuvered satellites for BeiDou GEO and IGSO. The initial orbits of maneuvered satellites could be backward forecasted according to the precise orbit products. The systematic errors caused by unmodeled maneuvered force are absorbed by estimated pseudo-stochastic pulses. The proposed method for determining the precise orbits of maneuvered satellites is validated by analyzing data of stations from the Multi-GNSS Experiment (MGEX). The results show that the precise orbits of maneuvered satellites can be estimated correctly when orbit maneuvering, which could supplement the precise products from the analysis centers of IGS and iGMAS. It can significantly improve the integrality and continuity of the precise products and subsequently provide better precise products for users.

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Network Effects and Handling of the Geocenter Motion in Multi‐GNSS Processing

Cited by 30 publications

References 46 publications

Impact of network constraining on the terrestrial reference frame realization based on SLR observations to LAGEOS

Impact of network constraining on the terrestrial reference frame realization based on SLR observations to LAGEOS

Toward the 1-cm Galileo orbits: challenges in modeling of perturbing forces

Precise Orbit Determination for BeiDou GEO/IGSO Satellites during Orbit Maneuvering with Pseudo-Stochastic Pulses

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