Comparison of GOCE-GPS gravity fields derived by different approaches

GPS data collected by satellite gravity missions can be used for extracting the long-wavelength part of the Earth's gravity field. We propose a new data processing method which makes use of the 'average acceleration' approach to gravity field modelling. In this method, satellite accelerations are directly derived from GPS carrier phase measurements with an epoch-differenced scheme. As a result, no ambiguity solutions are needed and the systematic errors that do not change much from epoch to epoch are largely eliminated. The GPS data collected by the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite mission are used to demonstrate the added value of the proposed method. An analysis of the residual accelerations shows that accelerations derived in this way are more precise, with noise being reduced by about 20 and 5% at the cross-track component and the other two components, respectively, as compared to those based on kinematic orbits. The accelerations obtained in this way allow the recovery of the gravity field to a slightly higher maximum degree compared to the solution based on kinematic orbits. Furthermore, the gravity field solution has an overall better performance. Errors in spherical harmonic coefficients are smaller, especially at low degrees. The cumulative geoid height error is reduced by about 15 and 5% up to degree 50 and 150, respectively. An analysis in the spatial domain shows that large errors along the geomagnetic equator, which are caused by a high electron density coupled with large short-term variations, are substantially reduced. Finally, the new method allows for a better observation of mass transport signals. In particular, sufficiently realistic signatures of regional mass anomalies in North America and south-west Africa are obtained.

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“…In the last decade, several techniques have been developed to exploit the kinematic orbits for gravity field modelling (e.g. Baur et al 2014). …”

Section: Introductionmentioning

confidence: 99%

Earth’s gravity field modelling based on satellite accelerations derived from onboard GPS phase measurements

Guo

Ditmar

Zhao

et al. 2017

J Geod

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“…There are numerous numerical differentiators that could be used in this approach, including polynomial interpolation, Newton-Gregory differentiation, and Taylor-MacLaurin differentiation [26]. With reference to the analysis of the computational efficiency and performance in Baur et al [8], we adopted the sixth-order seven-point polynomial fitting in this article. The basic formula for polynomial interpolation depending on the time difference τ is expressed as [26]:…”

Section: Numerical Differentiation Methodsmentioning

confidence: 99%

“…SST-hl is a highly sophisticated technique to map the long-wavelength spectrum of the gravity field [5][6][7]. There are four methods for gravity field recovery that use SST-hl observations: celestial mechanics, energy balance, short-arc, and acceleration methods [8]. According to the types of differentiated acceleration, two acceleration methods exist: the average acceleration method and point-wise acceleration method [9].…”

Section: Introductionmentioning

confidence: 99%

“…According to the types of differentiated acceleration, two acceleration methods exist: the average acceleration method and point-wise acceleration method [9]. Baur et al [8] and Pail et al [10] compared the different methods for modeling gravity field models with the GOCE SST-hl data and pointed out that, with the exception of the energy balance method, the other three methods had a comparable performance. The celestial mechanics approach is confronted with a large computational effort due to the integration of the variation equations and a nonlinear system of equations; in the case of the energy balance method, space gravity spectroscopy information is exclusively scalar and not available in all three directions [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Gravity Field Model Determination Based on GOCE Satellite Point-Wise Accelerations Estimated from Onboard Carrier Phase Observations

et al. 2019

Remote Sensing

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GPS-based, satellite-to-satellite tracking observations have been extensively used to elaborate the long-scale features of the Earth’s gravity field from dedicated satellite gravity missions. We proposed compiling a satellite gravity field model from Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite accelerations directly estimated from the onboard GPS data using the point-wise acceleration approach, known as the carrier phase differentiation method. First, we composed the phase accelerations from the onboard carrier phase observations based on the sixth-order seven-point differentiator, which can eliminate the carrier phase ambiguity for Low Earth Orbiter (LEO). Next, the three-dimensional (3D) accelerations of the GOCE satellite were estimated from the derived phase accelerations as well as GPS satellite ephemeris and precise clock products. Finally, a global gravity field model up to the degree and order (d/o) 130 was compiled from the 71 days and nearly 2.5 years of 3D satellite accelerations. We also recovered three gravity field models up to d/o 130 from the accelerations derived by differentiating the kinematic orbits of European Space Agency (ESA), Graz, and School of Geodesy and Geomatics (SGG), which was the orbit differentiation method. We analyzed the accuracies of the derived accelerations and the recovered gravity field models based on the carrier phase differentiation method and orbit differentiation method in time, frequency, and spatial domain. The results showed that the carrier phase derived acceleration observations had better accuracy than those derived from kinematic orbits. The accuracy of the recovered gravity field model based on the carrier phase differentiation method using 2.5 years observations was higher than that of the orbit differentiation solutions for degrees greater than 70, and worse than Graz-orbit solution for degrees less than 70. The cumulative geoid height errors of carrier phase, ESA-orbit, and Graz-orbit solutions up to degree and order 130 were 17.70cm, 21.43 cm, and 22.11 cm, respectively.

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“…For instance, Jäggi et al (2011) determined the GOCE-only gravity field model with kinematic orbits using the celestial mechanics approach. Baur et al (2014) utilized GOCE orbits to compare the solutions derived from celestial mechanics approach, short arc approach, point-wise acceleration approach and averaged acceleration approach. Visser et al (2014) and Jäggi et al (2015) discussed the possibility of determining temporal gravity field model solely with kinematic orbits.…”

Section: Introductionmentioning

confidence: 99%

HUST-GOGRA2018s: A new gravity field model derived from the combination of GRACE and GOCE data

Zhou¹,

Xu²,

Luo³

et al. 2019

Terr. Atmos. Ocean. Sci.

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A new satellite-only gravity field model entitled HUST-GOGRA2018s is developed by the combination of GRACE and GOCE data in this study. The modified dynamic approach is applied for GRACE data processing, while the space-wise least square method with a cascade filter is utilized for GOCE data processing. The GRACE-only model HUST-Grace2016s and GOCE-only model HUST-GOCE2018s are then computed, respectively. Our new developed GRACE-only model HUST-Grace2016s performs better than AIUB-GRACE03S, GGM05S, Tongji-GRACE01S at higher degrees, and the quality of our GOCE-only model HUST-GOCE2018s is also better than that of GO_CONS_GCF_2_TIM_R2 and GO_CONS_GCF_2_SPW_ R2. The combination is subsequently implemented by the superposition of GRACE and GOCE full normal equations. During the combination, the optimal weight is determined by the least-squares combined adjustment method with parametric covariance approach (LS-PCA) and the spectral combination method, respectively. The comparison result demonstrates that LS-PCA is more proper for the combination. As a result, the final HUST-GOGRA2018s model is developed. Validated by external gravity field models, the results demonstrate that the HUST-GOGRA2018s is dominated by GRACE data for the spherical harmonic coefficients lower than degree 60 and GOCE data for the spherical harmonic coefficients higher than degree 150, and its performance is better than that of GOCO01S.

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Comparison of GOCE-GPS gravity fields derived by different approaches

Abstract: SummaryDegree-error RMS; geoid error Formal errors; empirical errors & geoid height differences (w.r.t. ITG-Grace2010s)

Cited by 21 publications

References 38 publications

Earth’s gravity field modelling based on satellite accelerations derived from onboard GPS phase measurements

Earth’s gravity field modelling based on satellite accelerations derived from onboard GPS phase measurements

Gravity Field Model Determination Based on GOCE Satellite Point-Wise Accelerations Estimated from Onboard Carrier Phase Observations

HUST-GOGRA2018s: A new gravity field model derived from the combination of GRACE and GOCE data

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