Gravity Field Recovery Using High-Precision, High–Low Inter-Satellite Links

Past temporal gravity field solutions from the Gravity Recovery and Climate Experiment (GRACE), as well as current solutions from GRACE Follow-On, suffer from temporal aliasing errors due to undersampling of the signal to be recovered (e.g., hydrology), which arise in terms of stripes caused by the north–south observation direction. In this paper, we investigate the potential of the proposed mass variation observing system by high–low inter-satellite links (MOBILE) mission. We quantify the impact of instrument errors of the main sensors (inter-satellite link and accelerometer) and high-frequency tidal and non-tidal gravity signals on achievable performance of the temporal gravity field retrieval. The multi-directional observation geometry of the MOBILE concept with a strong dominance of the radial component result in a close-to-isotropic error behavior, and the retrieved gravity field solutions show reduced temporal aliasing errors of at least 30% for non-tidal, as well as tidal, mass variation signals compared to a low–low satellite pair configuration. The quality of the MOBILE range observations enables the application of extended alternative processing methods leading to further reduction of temporal aliasing errors. The results demonstrate that such a mission can help to get an improved understanding of different components of the Earth system.

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The Impact of Temporal Gravity Variations on GOCE Gravity Field Recovery

Observation of the Earth System from Space ◽

10.1007/3-540-29522-4_18 ◽

2006 ◽

pp. 255-269 ◽

Cited By ~ 3

Author(s):

Oleg Abrikosov ◽

Focke Jarecki ◽

Jürgen Müller ◽

Svetozar Petrovic ◽

Peter Schwintzer

Keyword(s):

Gravity Field ◽

Gravity Field Recovery ◽

Gravity Variations ◽

The Impact ◽

Temporal Gravity

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Effects of Interferometric Radar Altimeter Errors on Marine Gravity Field Inversion

Sensors ◽

10.3390/s20092465 ◽

2020 ◽

Vol 20 (9) ◽

pp. 2465

Author(s):

Xiaoyun Wan ◽

Shuanggen Jin ◽

Bo Liu ◽

Song Tian ◽

Weiya Kong ◽

...

Keyword(s):

Gravity Field ◽

Gravity Anomalies ◽

Ocean Surface ◽

Radar Altimeter ◽

The North ◽

Phase Errors ◽

Marine Gravity ◽

East Component ◽

The Impact ◽

Field Inversion

The traditional altimetry satellite, which is based on pulse-limited radar altimeter, only measures ocean surface heights along tracks; hence, leads to poorer accuracy in the east component of the vertical deflections compared to the north component, which in turn limits the final accuracy of the marine gravity field inversion. Wide-swath altimetry using radar interferometry can measure ocean surface heights in two dimensions and, thus, can be used to compute vertical deflections in an arbitrary direction with the same accuracy. This paper aims to investigate the impact of Interferometric Radar Altimeter (InRA) errors on gravity field inversion. The error propagation between gravity anomalies and InRA measurements is analyzed, and formulas of their relationship are given. By giving a group of possible InRA parameters, numerical simulations are conducted to analyze the accuracy of gravity anomaly inversion. The results show that the accuracy of the gravity anomalies is mainly influenced by the phase errors of InRA; and the errors of gravity anomalies have a linear approximation relationship with the phase errors. The results also show that the east component of the vertical deflections has almost the same accuracy as the north component.

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A multilayer approach and its application to model a local gravimetric quasi-geoid model over the North Sea: QGNSea V1.0

Geoscientific Model Development ◽

10.5194/gmd-11-4797-2018 ◽

2018 ◽

Vol 11 (12) ◽

pp. 4797-4815 ◽

Cited By ~ 2

Author(s):

Yihao Wu ◽

Zhicai Luo ◽

Bo Zhong ◽

Chuang Xu

Keyword(s):

Gravity Field ◽

North Sea ◽

Ocean Circulation ◽

Goodness Of Fit ◽

Gravity Data ◽

Single Layer ◽

Geoid Model ◽

The North ◽

Gravity Field Recovery ◽

The North Sea

Abstract. A multilayer approach is set up for local gravity field recovery within the framework of multi-resolution representation, where the gravity field is parameterized as the superposition of multiple layers of Poisson wavelets located at different depths beneath the Earth's surface. The layers are designed to recover gravity signals at different scales, where the shallow and deep layers mainly capture the short- and long-wavelength signals, respectively. The depths of these layers are linked to the locations of different anomaly sources beneath the Earth's surface, which are estimated by wavelet decomposition and power spectrum analysis. For testing the performance of this approach, a gravimetric quasi-geoid model over the North Sea, QGNSea V1.0, is modeled and validated against independent control data. The results show that the multilayer approach fits the gravity data better than the traditional single-layer approach, particularly in regions with topographical variation. An Akaike information criterion (AIC) test shows that the multilayer model obtains a smaller AIC value and achieves a better balance between the goodness of fit of data and the simplicity of the model. Further, an evaluation using independent GPS/leveling data tests the ability of regional models computed from different approaches towards realistic extrapolation, which shows that the accuracies of the QGNSea V1.0 derived from the multilayer approach are better by 0.4, 0.9, and 1.1 cm in the Netherlands, Belgium, and parts of Germany, respectively, than that using the single-layer approach. Further validation with existing models shows that QGNSea V1.0 is superior with respect to performance and may be beneficial for studying ocean circulation between the North Sea and its neighboring waters.

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Analysis of attitude errors in GRACE range-rate residuals - a comparison between SCA1B and the reprocessed attitude fused product (SCA1B +ACC1B)

10.31219/osf.io/sqfcb ◽

2018 ◽

Author(s):

Sujata Goswami

Keyword(s):

Gravity Field ◽

Range Measurements ◽

Precise Knowledge ◽

Range Rate ◽

The Impact ◽

Temporal Gravity ◽

Gravity Field Models ◽

Fundamental Requirement

For the missions like GRACE, the precise knowledge of the satellite’s attitude is a fundamental requirement forthe realization of the inter-satellite ranging principle. It is not only essential for the realization of the precise in-orbit intersatellitepointing, but also for the recovery of accurate temporal gravity field models. Here we present a comparative studyof two attitude datasets. One of them is the standard SCA1B RL02 datasets provided by JPL NASA and another is a fusedattitude dataset computed at TU Graz, based on the combination of ACC1B angular accelerations and SCA1B quaternions.Further, we also present the impact of the attitude datasets on the inter-satellite range measurements by analyzing theirresiduals. Our analysis reveals the significant improvement in the attitude due to the reprocessed product and reducedvalue of residuals computed from the reprocessed attitude

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Assessment of two methods for gravity field recovery from GOCE GPS-SST orbit solutions

Advances in Geosciences ◽

10.5194/adgeo-1-121-2003 ◽

2003 ◽

Vol 1 ◽

pp. 121-126 ◽

Cited By ~ 8

Author(s):

K. Arsov ◽

R. Pail

Keyword(s):

Gravity Field ◽

Numerical Integration ◽

Precise Orbit Determination ◽

Integral Approach ◽

Satellite Mission ◽

Long Wavelength ◽

Alternative Processing ◽

Gravity Field Recovery ◽

Least Squares Adjustment

Abstract. In the course of the GOCE satellite mission, the high-low Satellite to Satellite Tracking (SST) observations have to be processed for the determination of the long wavelength part of the Earth’s gravity field. This paper deals with the formulation of the high-low SST observation equations, as well as the methods for gravity field recovery from orbit information. For this purpose, two approaches, i.e. the numerical integration of orbit perturbations, and the evaluation of the energy equation based on the Jacobi integral, are presented and discussed. Special concern is given to the numerical properties of the corresponding normal equations. In a closed-loop simulation, which is based on a realistic orbit GOCE configuration, these methods are compared and assessed. However, here we process a simplified case assuming that non-conservative forces can be perfectly modelled. Assuming presently achievable accuracies of the Precise Orbit Determination (POD), it turns out that the numerical integration approach is still superior, but the energy integral approach may be an interesting alternative processing strategy in the near future.Key words. High-low SST – gravity field – GOCE – variational equations – least squares adjustment

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Static and temporal gravity field recovery using grace potential difference observables

Advances in Geosciences ◽

10.5194/adgeo-1-19-2003 ◽

2003 ◽

Vol 1 ◽

pp. 19-26 ◽

Cited By ~ 14

Author(s):

S.-C. Han ◽

C. Jekeli ◽

C. K. Shum

Keyword(s):

Gravity Field ◽

Time Variable ◽

Potential Difference ◽

Gps Tracking ◽

Orbital Parameter ◽

Energy Relation ◽

Disturbing Potential ◽

Gravity Field Recovery ◽

Grace Mission ◽

Temporal Gravity

Abstract. The gravity field dedicated satellite missions like CHAMP, GRACE, and GOCE are supposed to map the Earth’s global gravity field with unprecedented accuracy and resolution. New models of Earth’s static and time-variable gravity field will be available every month as one of the science products from GRACE. Here we present an alternative method to estimate the gravity field efficiently using the in situ satellite-to-satellite observations at the altitude and show results on static as well as temporal gravity field recovery. Considering the energy relation between the kinetic energy of the satellite and the gravitational potential, the disturbing potential difference observations can be computed from the orbital parameter vectors in the inertial frame, using the high-low GPS-LEO GPS tracking data, the low-low satelliteto- satellite GRACE measurements, and data from 3-axis accelerometers (Jekeli, 1999). The disturbing potential observation also includes other potentials due to tides, atmosphere, other modeled signals (e.g. N-body) and the geophysical fluid signals (hydrological and oceanic mass variations), which should be recoverable from GRACE mission with a monthly resolution. The simulation results confirm that monthly geoid accuracy is expected to be a few cm with the 160 km resolution (up to degree and order 120) once other corrections are made accurately. The time-variable geoids (ocean and ground water mass) might be recovered with a noise-to-signal ratio of 0.1 with the resolution of 800 km every month assuming no temporal aliasing.Key words. GRACE mission, Energy integral, Geopotential, Satellite-to-satellite tracking, Temporal gravity field

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The re-analysis on the raw data processing of KBR and LRI on GRACE-FO

10.5194/egusphere-egu21-793 ◽

2021 ◽

Author(s):

Yihao Yan ◽

Changqing Wang ◽

Vitali Müller ◽

Min Zhong ◽

Lei Liang ◽

...

Keyword(s):

Gravity Field ◽

Science Data ◽

Raw Data ◽

Gravity Field Recovery ◽

Offset Correction ◽

Instrument Noise ◽

Time Correction ◽

Gravity Recovery ◽

Temporal Gravity ◽

Good Agreement

<div> <p>The KBR (K-Band ranging instrument) and LRI (Laser Interferometer) are used to measure the distance variations between the twin spacecraft, which is one of the most important observations used for temporal gravity field recovery. The data pre-processing from raw or so-called Level-1A into the Level-1B format, which is suited for gravity field recovery, is a key step. Although Level-1B files are made publicly available by the GRACE-FO Science Data System (SDS), it has been shown that alternative Level-1B datasets may yield improved the results of gravity field<sup>[1]</sup>. Investigations of the pre-processing may allow us to improve the gravity recovery strategy and are essential to support developments of gravimetric satellite missions in China, such as TianQin-2 project. The pre-processing normally includes the time-tag synchronization, filtering and resampling, and other corrections, e.g. light-time correction for both instruments and antenna offset correction for KBR. We re-processed the Level-1A data of KBR and LRI to the Level1B using code developed at IGG/Wuhan. The results show good agreement in case of the RL04 KBR data, i.e. the differences between IGG-KBR1B and SDS-KBR1B are about three orders of magnitude lower than the instrument noise level for KBR. For the LRI, we found that phase jumps are not removed completely in the SDS-LRI1B products. As shown by Abich<sup>[2]</sup>, these phase jumps in the LRI phase observations are mainly coincident with thruster activations. Our work will analyze the impacts of different processing methods of the raw data on post-fit residuals and the gravity field recovery based on IGG-KBR1B and IGG-LRI1B datasets.</p> <p>&#160;</p> <div> <p>[1] Wiese, D.: SDS Level-2/-3 JPL, GRACE/GRACE-FO Science Team Meeting 2020, online, 27 October&#8211;29 Oct 2020, GSTM2020-75, https://doi.org/10.5194/gstm2020-75, 2020.</p> <p>[2]&#160;&#160;&#160; Abich K, Abramovici A, Amparan B, et al. In-Orbit Performance of the GRACE Follow-on Laser Ranging Interferometer [J]. Phys Rev Lett, 2019, 123(3): 031101, https://doi.org/10.1103/PhysRevLett.123.031101.</p> </div> </div><p>&#160;</p>

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

Surveys in Geophysics ◽

10.1007/s10712-020-09626-0 ◽

2021 ◽

Author(s):

Jan Martin Brockmann ◽

Till Schubert ◽

Wolf-Dieter Schuh

Keyword(s):

Gravity Field ◽

Ocean Circulation ◽

Gravity Anomalies ◽

Geoid Height ◽

Gravity Gradients ◽

Data Set ◽

Gravity Field Recovery ◽

Global Gravity ◽

The Impact ◽

Goce Satellite

AbstractAfter 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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