The gravity field model IGGT_R1 based on the second invariant of the GOCE gravitational gradient tensor

Lu, Biao; Luo, Zhicai; Zhong, Bo; Zhou, Hao; Flechtner, Frank; Förste, Christoph; Barthelmes, Franz; Zhou, Rui

doi:10.1007/s00190-017-1089-8

Cited by 20 publications

(23 citation statements)

References 29 publications

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“…On the other hand, the accuracy of the comparison with EIGEN‐6C4 is about 3 mGal, which means that airborne gravimetry can improve the current model at locations with lack of good quality gravimetry data, such as Antarctica. Here, the best airborne gravimetry data from the GEOHALO project can be found from GFZ Data Service (Lu, Barthelmes, et al, ).…”

Section: Numerical Results and Analysismentioning

confidence: 99%

“…This ensures that a gravimetry campaign can be also accomplished across hard‐to‐reach regions like mountains as well as the North and South Polar regions. Especially the latter is crucial because the most recent satellite‐only gravity field models suffer from gaps over the polar regions which were caused by the inclination of the Gravity field and steady‐state Ocean Circulation Explorer (GOCE) orbit of 96.7 0 (see, e.g., Lu, Luo, et al, ; Pail et al, ; Rudolph et al, ). Hence, the experiment described in this article is an airborne gravimetry study for exploring Antarctica in the future, too.…”

Section: Introductionmentioning

confidence: 99%

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Airborne Gravimetry of GEOHALO Mission: Data Processing and Gravity Field Modeling

Barthelmes

Förste

et al. 2017

JGR Solid Earth

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Airborne gravimetry is a crucial method to improve our knowledge about the Earth gravity field, especially in hard‐to‐access regions. Generally, the accuracy of airborne gravimetry is several milligals, which is suitable for filling the so‐called polar gaps in satellite‐derived global gravity field models. Here some investigations based on airborne gravity measurements from the GEOHALO mission over Italy are presented. To subtract the vertical accelerations from the values measured by the gravimeter, four different versions of kinematic accelerations were derived from Global Navigation Satellite Systems (GNSS) recordings. To remove the high‐frequency noise, a low‐pass filter with a cutoff wavelength of 200 s was applied to both Chekan‐AM measurements and kinematic accelerations from GNSS. To investigate how future airborne gravity campaigns could be designed, a dedicated flight track was repeated two times showing that the equipment worked well also at higher altitude and speed. From the final best results follows an RMS of gravity differences at crossover points of 1.4 mGal, which, according to the law of error propagation, implies the accuracy of a single measurement to be 1.4/2≈1 mGal. To demonstrate how a satellite‐only gravity field model can be improved by airborne measurements, a gravity field model for the GEOHALO region has been computed. To compute also an improved regional geoid model, the point mass modeling (PMM) and the remove‐compute‐restore (RCR) technique, using a recent satellite‐only model and residual terrain modeling (RTM), were applied. Finally, GNSS/leveling points have been used to check the quality of the regional point mass model.

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Section: Numerical Results and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Airborne Gravimetry of GEOHALO Mission: Data Processing and Gravity Field Modeling

Barthelmes

Förste

et al. 2017

JGR Solid Earth

Self Cite

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“…But, as the higher order invariants are nonlinear functions of all tensor elements-including the inaccurate ones-for real data analysis linearization and substitution with model information are required, which again requires the satellites' orientation for synthesization. Models like IGGT_R1 (Lu et al 2018) indicate that a strong bias toward the used 'fill-in' models is introduced.…”

Section: Introductionmentioning

confidence: 99%

An Improved Model of the Earth’s Static Gravity Field Solely Derived from Reprocessed GOCE Data

2021

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After it was found that the gravity gradients observed by the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite could be significantly improved by an advanced calibration, a reprocessing project for the entire mission data set was initiated by ESA and performed by the GOCE High-level processing facility (GOCE HPF). One part of the activity was delivering the gravity field solutions, where the improved level 1b and level 2 data serve as an input for global gravity field recovery. One well-established approach for the analysis of GOCE observations is the so-called time-wise approach. Basic characteristics of the GOCE time-wise solutions is that only GOCE observations are included to remain independent of any other gravity field observables and that emphasis is put on the stochastic modeling of the observations’ uncertainties. As a consequence, the time-wise solutions provide a GOCE-only model and a realistic uncertainty description of the model in terms of the full covariance matrix of the model coefficients. Within this contribution, we review the GOCE time-wise approach and discuss the impact of the improved data and modeling applied in the computation of the new GO_CONS_EGM_TIM_RL06 solution. The model reflects the Earth’s static gravity field as observed by the GOCE satellite during its operation. As nearly all global gravity field models, it is represented as a spherical harmonic expansion, with maximum degree 300. The characteristics of the model and the contributing data are presented, and the internal consistency is demonstrated. The updated solution nicely meets the official GOCE mission requirements with a global mean accuracy of about 2 cm in terms of geoid height and 0.6 mGal in terms of gravity anomalies at ESA’s target spatial resolution of 100 km. Compared to its RL05 predecessor, three kinds of improvements are shown, i.e., (1) the mean global accuracy increases by 10–25%, (2) a more realistic uncertainty description and (3) a local reduction of systematic errors in the order of centimeters.

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“…The application of 3 tensor invariants in the verification of the gravitational gradients can be expressed as (Baur et al, 2008;Lu et al, 2018…”

Section: Discussion Of the Calibration Resultsmentioning

confidence: 99%

An upward continuation method based on spherical harmonic analysis and its application in the calibration of satellite gravity gradiometry data

Zhu

et al. 2021

Preprint

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Abstract. The ground gravity anomalies can be used to calibrate and validate the satellite gravity gradiometry data. In this study, an upward continuation method of ground gravity data based on spherical harmonic analysis is proposed, which can be applied to the calibration of satellite observations from the European Space Agency's Gravity Field and Steady-State Ocean Circulation Explorer (GOCE). Here, the following process was conducted to apply this method. The accuracy of the upward continuation method based on spherical harmonic analysis was verified using simulated ground gravity anomalies. The DTU13 global gravity anomaly data were used to determine the calibration parameters of the GOCE gravitational gradients based on the spherical harmonic analysis method. The trace and the tensor invariants I2, I3 of the gravitational gradients were used to verify the calibration results. The results revealed that the upward continuation errors based on spherical harmonic analysis were much smaller than the noise level in the measurement bandwidth of the GOCE gravity gradiometer. The scale factors of the Vxx, Vyy, Vzz, and Vyz components were determined at an order of magnitude of approximately 10−2, the Vxz component was approximately 10−3, and the Vxy component was approximately 10−1. The traces of gravitational gradients after calibration were improved when compared with the traces before calibration and were slightly better than the EGG_TRF_2 data released by the European Space Agency (ESA). In addition, the relative errors of the tensor invariants I2, I3 of the gravitational gradients after calibration were significantly better than those before calibration. In conclusion, the upward continuation method based on spherical harmonic analysis could meet the external calibration accuracy requirements of the gradiometer.

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The gravity field model IGGT_R1 based on the second invariant of the GOCE gravitational gradient tensor

Cited by 20 publications

References 29 publications

Airborne Gravimetry of GEOHALO Mission: Data Processing and Gravity Field Modeling

Airborne Gravimetry of GEOHALO Mission: Data Processing and Gravity Field Modeling

An Improved Model of the Earth’s Static Gravity Field Solely Derived from Reprocessed GOCE Data

An upward continuation method based on spherical harmonic analysis and its application in the calibration of satellite gravity gradiometry data

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