In this manuscript, we introduce the Ionospheric Tomographic Common Clock (ITCC) model of undifferenced uncombined GNSS measurements. It is intended for improving the Wide Area precise positioning in a consistent and simple way in the multi-GNSS context, and without the need of external precise real-time products. This is the case, in particular, of the satellite clocks, which are estimated at the

A new interpretation of the 2016 Meinong earthquake is proposed based on the Synthetic Aperture Radar (SAR) satellites, high-rate GPS and strong motion data. The fault geometry is firstly estimated by the Interferometric Synthetic Aperture Radar (InSAR) surface deformation data. Then, the coseismic rupture process is inferred through the 1-Hz GPS and strong motion data based on the estimated fault

CONT17 is an observation campaign of continuous Very Long Baseline Interferometry (VLBI) sessions for a period of 15 days, carried out by the International VLBI Service for Geodesy and Astrometry (IVS). This campaign represents an interesting opportunity for the inter-comparison of space geodetic techniques given that they share the same observability conditions in co-located sites. In this work, VLBI

Although ionosphere-weighted GNSS parameter estimation is a popular technique for strengthening estimator performance in the presence of ionospheric delays, no provable rules yet exist that specify the needed weighting in dependence on ionospheric circumstances. The goal of the present contribution is therefore to develop and present the ionospheric conditions that need to be satisfied in order for

The accuracy of geodetic Very Long Baseline Interferometry (VLBI) is affected by water vapour in the atmosphere in terms of variations in the signal propagation delay at the different stations. This “wet” delay may be estimated directly from the VLBI data, as well as from independent instruments, such as collocated microwave radiometers. Rather than having stand-alone microwave radiometers we have

Deformation measurements from satellite-borne synthetic aperture radar interferometry (InSAR) are usually measured relative to an arbitrary reference point (RP) of assumed stability over time. For InSAR rates to be reliably interpreted as uplift or subsidence, they must be connected to a defined Earth-centred terrestrial reference frame (TRF), usually made through GNSS continuously operating reference

The new-generation relative gravimeter Scintrex CG6 is put on the test bench: Its performance is compared to its predecessor, the Scintrex-CG5. A CG5 Scintrex and a CG6 Scintrex were both submitted to the same rigorous tests, which have been developed in recent years to highlight some defects of the CG5. The results show that the CG6 always performs better than the CG5. For instance, the instrumental

TOPEX/Poseidon, Jason-1, Jason-2 and Jason-3 altimeter missions have provided 27 + years of uninterrupted Total Electron Content (TEC) measurements since 1992, with unprecedented precision. Nevertheless, the issue of a possible systematic bias in the data was identified immediately after first TOPEX measurements were compared with measurements from other sources. The bias issue has remained open for

The Minimal Detectable Displacement (MDD) is an important measure of monitoring networks sensitivity to displacements. In addition to the accuracy criteria, it is used as a detectability criterion in the optimal design of such networks. The paper examines whether the MDD provides grounds for verifying the correctness of the confidence, and the significance thresholds applied in the analyses of the

Persistent scatterer interferometric synthetic aperture radar (PS-InSAR) is a widely used technique for local ground deformation estimation due to its millimetric accuracy and full-resolution results. However, with the enhancement of data acquisition capability of the SAR sensors, larger coverage and higher temporal-spatial resolution of SAR images can cause explosive increase and uneven distribution

The Sentinel-6 (or Jason-CS) altimetry mission provides a long-term extension of the Topex and Jason-1/2/3 missions for ocean surface topography monitoring. Analysis of altimeter data relies on highly-accurate knowledge of the orbital position and requires radial RMS orbit errors of less than 1.5 cm. For precise orbit determination (POD), the Sentinel-6A spacecraft is equipped with a dual-constellation

In this contribution, we introduce a generalized Kalman filter with precision in recursive form when the stochastic model is misspecified. The filter allows for a relaxed dynamic model in which not all state vector elements are connected in time. The filter is equipped with a recursion of the actual error-variance matrices so as to provide an easy-to-use tool for the efficient and rigorous precision

In recent strapdown airborne and shipborne gravimetry campaigns with servo accelerometers of the widely used Q-Flex type, results have been impaired by heading-dependent measurement errors. This paper shows that the effect is, in all likelihood, caused by the sensitivity of the Q-Flex type sensor to the Earth’s magnetic field. In order to assess the influence of magnetic fields on the utilised strapdown

The International Height Reference System (IHRS), adopted by International Association of Geodesy (IAG) in its Resolution No. 1 at the XXVI General Assembly of the International Union of Geodesy and Geophysics (IUGG) in Prague in 2015, contains two novelties. Firstly, the mean-tide concept is adopted for handling the permanent tide. While many national height systems continue to apply the mean-tide

The article Integrated processing of ground- and space-based GPS observations: improving GPS satellite orbits observed with sparse ground networks, written by Wen Huang, Benjamin Männel, Pierre Sakic, Maorong Ge & Harald Schuh was originally published electronically on the publisher’s internet portal on [10 October 2020] without open access.

A modified multipath error mitigation method using the multi-point hemispherical grid model (MHGM) is proposed, and the influence of changes in the observation environments of IGS stations on their data quality is evaluated. The multipath error models of different satellite pairs for different observation periods can be established using the integrated multi-GNSS data in the proposed method. The test

The invariants of gravity (or gravitational) gradient tensor can be applied as the additional internal parameters for the gravity gradient tensor, which have been widely used in the recovery of the global gravity field models in geodesy, interpretation of geophysical properties in geophysics, and gravity matching in navigation and positioning. In this contribution, we provide the general formulae of

We investigated the suitability of the astronomical 15 GHz Very Long Baseline Array (VLBA) observing program MOJAVE-5 for estimation of geodetic parameters, such as station coordinates and Earth orientation parameters. We processed a concurrent dedicated VLBA geodesy program observed at 2.3 GHz and 8.6 GHz starting on September 2016 through July 2020 as reference dataset. We showed that the baseline

The Satellite Laser Ranging (SLR) technique provides very accurate distance measurements to artificial Earth satellites. SLR is employed for the realization of the origin and the scale of the terrestrial reference frame. Despite the high precision, SLR observations can be affected by various systematic errors. So far, range biases were used to account for systematic measurement errors and mismodeling

In this contribution, we extend the principle of integer bootstrapping (IB) to a vectorial form (VIB). The mathematical definition of the class of VIB-estimators is introduced together with their pull-in regions and other properties such as probability bounds and success rate approximations. The vectorial formulation allows sequential block-by-block processing of the ambiguities based on a user-chosen

The accuracy of the tropospheric mapping functions is greatly influenced by the mapping function modeling methods. In the past decades, the ‘fast’ method rather than the rigorous least-squares methods was dominantly used for the development of mapping functions, such as Vienna Mapping Functions 1 (VMF1), considering the convergence issue and computation efficiency. In this study, we reconsider the

We present a partition-enhanced least-squares collocation (PE-LSC) which comprises several modifications to the classical LSC method. It is our goal to circumvent various problems of the practical application of LSC. While these investigations are focused on the modeling of the exterior gravity field the elaborated methods can also be used in other applications. One of the main drawbacks and current

Optical clocks improved the accuracy of state-of-the-art cesium clocks by more than two orders of magnitude and enabled frequency comparison with a fractional uncertainty of one part in 1018. Gravitational redshift of two such clocks allows determining their height difference with an uncertainty of 1 cm. In Europe, chronometric leveling has been extensively conducted for unifying the height reference

PPP-RTK extends the precise point positioning (PPP) concept by incorporating the idea of integer ambiguity resolution underlying the real-time kinematic (RTK) technique, making rapid initialization and high accuracy attainable with a standalone receiver. While PPP-RTK has been well achieved by using global navigation satellite system code division multiple access observables, GLONASS PPP-RTK is nonetheless

The first objective of this paper is to assess by means of geodetic network analyses the impact of adding model-based hydrodynamic leveling data to the Unified European Leveling Network (UELN) data on the precision and reliability of the European Vertical Reference Frame (EVRF). In doing so, we used variance information from the latest UELN adjustment. The model-based hydrodynamic leveling data are

The utilization of Global Navigation Satellite System (GNSS) is becoming an attractive approach for the orbit determination of geostationary orbit (GEO) satellites. As a flight test for the feasibility of GNSS-based orbit determination at high orbit altitude, a GEO satellite named TJS-2 is launched. This satellite is equipped with a high-gain antenna, a pre-amplifier, and a high-sensitivity receiver

Previous studies mainly focused on second- and third-order gravitational potential gradients that these values are already measurable or that appropriate measurement principles are being developed. Although the higher-order (i.e. the order is larger than or equal to four) gravitational potential gradients cannot be observed now, with the development of science and technology, it will be hoped to measure

The associated Legendre functions constituting the kernel function of spherical harmonics have a wide range of applications in geodesic and geophysical fields, such as calculating the Green’s functions for a spherical Earth model. The analytical expressions for the infinite series involving the associated Legendre functions are useful. In this paper, starting with the generating function, we present

In this simulation study we analyze the benefit of ground-space optical two-way links (OTWL) for Galileo precise orbit determination (POD). OTWL is a concept based on continuous wave laser ranging and time transfer with modulated signals from and to ground stations. The measurements are in addition to Global Navigation Satellite System (GNSS) observations. We simulate the measurements with regard to

In forest areas, when using interferometric synthetic aperture radar (InSAR) technique to extract subcanopy topography, a key problem is how to reduce the impact of the forest-scattering process on InSAR height measurements. In this paper, we propose a new methodology for subcanopy topography extraction by making full use of single-baseline TanDEM-X InSAR data. The interferometric phase is used to

To obtain better zenith hydrostatic delay (ZHD) corrections for global navigation satellite system (GNSS) applications, seven types of Vienna mapping function 1 (VMF1) and VMF3-like ZHD models provided by the Vienna University of Technology (TU Wien, TUW), University of New Brunswick (UNB) and GeoForschungsZentrum Potsdam (GFZ) are evaluated. Firstly, we find that the conventional method for implementing

Wide-lane (WL) uncalibrated phase delay (UPD) is usually derived from Melbourne–Wübbena (MW) linear combination and is a prerequisite in Global Navigation Satellite Systems (GNSS) precise point positioning (PPP) ambiguity resolution (AR). MW is a linear combination of pseudorange and phase, and the accuracy is limited by the larger pseudorange noise which is about one hundred times of the carrier phase

The generation and use of GNSS analysis products that allow—particularly for the needs of single-receiver applications—precise point positioning with ambiguity resolution (PPP-AR) are becoming more and more popular. A general uncertainty concerns the question on how the necessary phase bias information should be provided to the PPP-AR user. Until now, each AR-enabling clock/bias representation method

Satellite altimetry and gravimetry are used to determine the mean seasonal cycle in relative sea level, a quantity relevant to coastal flooding and related applications. The main harmonics (annual, semiannual, terannual) are estimated from 25 years of gridded altimetry, while several conventional altimeter “corrections” (gravitational tide, pole tide, and inverted barometer) are restored. To transform

Abstract Acoustic positioning of the seafloor geodetic network is subject to the complex ocean environment. The measurements are strongly affected by time-varying and location-varying ocean physical phenomena. At first, the differential and undifferential acoustic positioning modes are analyzed. Then, a simple resilient observational model with range bias and time bias parameters is established. After

Tropospheric wet delay, the main source of which is water vapor, is one of the major factors affecting the accuracy of positioning techniques using microwave. Tropospheric tomography is a powerful method to reconstruct the water vapor content in four-dimensional (4D) space. This paper studies the effect of using function-based and voxel-based tropospheric tomography methods on the positioning accuracy

The electron density structures of the seismo-traveling ionospheric disturbances (STIDs) during the Tohoku earthquake are reconstructed by applying the three-dimensional computerized ionospheric tomography (3DCIT) technique with a 30-s time resolution for the first time. The vertical distribution of 3DCIT results is consistent with the constellation observing system for meteorology, ionosphere and

Many low earth orbit (LEO) missions have been launched recently for different geoscience studying purposes such as ionosphere detecting and gravity recovering. The onboard observations from LEO satellites provide us a great opportunity to estimate the differential code bias (DCB) which is vital for precise applications of global navigation satellites system. This paper mainly focuses on the contribution

One of the main tasks of Very Long Baseline Interferometry (VLBI) is the rapid determination of the highly variable Earth’s rotation expressed through the difference between Universal Time UT1 and Coordinated Universal Time UTC (dUT1). For this reason, dedicated one hour, single baseline sessions, called “Intensives”, are observed on a daily basis. Thus far, the optimal geometry of Intensive sessions

A continuously operating GNSS station within a lake interior is uncommon, but advantageous for testing the GNSS Interferometric Reflectometry (GNSS-IR) technique. In this research, GNSS-IR is used to estimate ten years of lake surface heights for Lake Taupō in New Zealand. This is achieved using data collected from station TGHO, approximately 4 km from the lake’s shoreline. Its reliability is assessed

The dearth of frequency-specific satellite antenna phase centers (APCs), such as GPS Block IIF L5 phase center offsets (PCOs) and BeiDou System (BDS) phase variations (PVs), inconveniences multi-frequency precise point positioning (PPP). We find that the GNSS observation biases caused by incorrect frequency-specific APCs are both spatially incoherent and time variable. This spatiotemporal incoherency

In this paper, we propose a method for the generation of real-time global ionospheric map (RT-GIM) of vertical total electron content (VTEC) from GNSS measurements. The need for interpolation arises from the fact that the ionospheric pierce point (IPP) measurements from satellites to stations are not distributed uniformly over the ionosphere, leaving unfilled gaps at oceans or poles. The method we

The paper presents local gravity field modelling in spatial domain using the finite element method (FEM). FEM as a numerical method is applied for solving the geodetic boundary value problem with oblique derivative boundary conditions (BC). For such a problem, we derive a new numerical scheme where the oblique derivative BC are considered directly at computational nodes on the discretized Earth’s topography

Precise point positioning (PPP) with wide-lane ambiguity resolution (PPP-WAR) can quickly achieve decimeter-level positioning accuracy, which is an essential improvement for real-time PPP in terms of reliability and accuracy. However, current implementations of PPP-WAR are based only on the standard Kalman filter (KF) under the assumption of uncorrelated measurements. As Global Navigation Satellite

A harmonic scalar field has a Laplacian (i.e., both source-free and curl-free) gradient vector field and vice versa. Despite the good performance of spherical harmonic series on modeling the gravitational field generated by spheroidal bodies (e.g., the Earth), the series may diverge inside the Brillouin sphere enclosing all field-generating mass. Divergence may realistically occur when determining

In this paper, we discuss some methods for the calculation of the Legendre polynomial difference \(P_{n - 1}(t) - P_{n + 1}(t)\). Such differences frequently appear when calculating the spherical harmonic coefficients of truncated spatial filters. By examining the relation between the Legendre polynomials and other classical orthogonal polynomials (i.e., Gegenbauer and Jacobi polynomials), we provide

We measured the components of the 31-m-long vector between the two very-long-baseline interferometry (VLBI) antennas at the Kokee Park Geophysical Observatory (KPGO), Hawaii, with approximately 1 mm precision using phase delay observables from dedicated VLBI observations in 2016 and 2018. The two KPGO antennas are the 20 m legacy VLBI antenna and the 12 m VLBI Global Observing System (VGOS) antenna

There are two dominating approaches of modeling the marine gravity field based on satellite altimetry observations. In this study, the marine gravity field is determined in four selected areas (Northwestern Atlantic, Hawaii ocean area, Mariana Trench area, and Aegean Sea) by using exact same input datasets but different methods which are based on sea surface height (SSH) and sea surface slope (SSS)

Precise point positioning (PPP) is receiving increasing interest due to its cost-effectiveness, global coverage and high accuracy. However, its application in the urban environment is still full of challenges due to the satellite tracking sky-view. Thus, we presented a comprehensive positioning model by fusing the multi-GNSS (global navigation satellite system) combination, GNSS/INS (inertial navigation

The National Institute of Metrology, China, successfully organized the 10th International Comparison of Absolute Gravimeters in its Changping Campus in 2017 (ICAG-2017). The ICAG-2017 is registered as the CCM.G-K2.2017 Key Comparison (KC) and Pilot Study (PS) in the frame of CIPM Mutual Recognition Arrangement of the International Committee for Weights and Measures (CIPM-MRA). KC instrument belongs

We present a 27-day-long common view measurement of an absolute cold atom gravimeter (CAG) and a relative iGrav superconducting gravimeter, which we use to calibrate the iGrav scale factor. This allowed us to push the CAG long-term stability down to the level of 0.5 nm s\(^{-2}\). We investigate the impact of the duration of the measurement on the uncertainty in the determination of the correlation

Precise point positioning (PPP) has proved its capacity to provide centimetre-level position solutions in open sky environments. However, the technique still suffers from relatively long initial convergence times. Research has proved the potential of ambiguity resolution (AR) to reduce the convergence time and three main methods are used to perform AR: the fractional cycle bias method, the decoupled

The elliptical harmonic method for gravity forward computation of two-dimensional (2D) bodies with constant, polynomial and exponential density distributions is presented. This paper gives the elliptical harmonic expansions for the gravity field of 2D bodies mainly including the gravitational attractions and gradients, and the conversions from the surface integral expressions of the elliptical harmonic

Within this work, a new geodetic very long baseline interferometry (VLBI) scheduling approach inspired by evolutionary processes based on selection, crossover and mutation is presented. It mimics the biological concept “surviving of the fittest” to iteratively explore the scheduling parameter space looking for the best solution. Besides providing high-quality results, one main benefit of the proposed

The attempt to quantify the corrections of lunisolar nutation components was made after analysis of six sets of Earth’s orientation parameters (EOP). The deviations of the long-term nutation components about IAU2006/IAU2000A precession–nutation model are consistent with the uncertainties suggested by Mathews et al. (J Geophys Res Solid Earth, 2002. https://doi.org/10.1029/2001JB000390), but they exceed

We apply three spherical-harmonic-based techniques to deliver external gravitational field models of the asteroid (101955) Bennu within its circumscribing sphere. This region is known to be peculiar for external spherical harmonic expansions, because it may lead to a divergent series. The studied approaches are (i) spectral gravity forward modelling via external spherical harmonics, (ii) the least-squares

The intradecadal variations in length-of-day (LOD) and their time-varying characteristics still need to be further studied. Given that the corresponding signal periods on the intradecadal scales are quite close to each other and the span of currently observed ΔLOD data (i.e., 1962–2019, only 57 years) is not long enough, accurate detection of these signals depends on using effective mathematical method

We present results from observation, correlation and analysis of interferometric measurements between the three geodetic very long baseline interferometry (VLBI) stations at the Onsala Space Observatory. In total, 25 sessions were observed in 2019 and 2020, most of them 24 h long, all using X band only. These involved the legacy VLBI station ONSALA60 and the Onsala twin telescopes, ONSA13NE and ONSA13SW

This paper studies the contribution of airborne gravity data to improvement of gravimetric geoid modelling across the mountainous area in Colorado, USA. First, airborne gravity data was processed, filtered, and downward-continued. Then, three gravity anomaly grids were prepared; the first grid only from the terrestrial gravity data, the second grid only from the downward-continued airborne gravity