A preliminary error analysis of the gravity field recovery from a lunar Satellite-to-Satellite mission

AbstractFor many developing countries such as Uganda, precise gravimetric geoid determination is hindered by the low quantity and quality of the terrestrial gravity data. With only one gravity data point per 65 km2, gravimetric geoid determination in Uganda appears an impossible task. However, recent advances in geoid modelling techniques coupled with the gravity-field anomalies from the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite mission have opened new avenues for geoid determination especially for areas with sparse terrestrial gravity. The present study therefore investigates the computation of a gravimetric geoid model overUganda (UGG2014) using the Least Squares Modification of Stokes formula with additive corrections. UGG2014 was derived from sparse terrestrial gravity data from the International Gravimetric Bureau, the 3 arc second SRTM ver4.1 Digital Elevation Model from CGIAR-CSI and the GOCE-only global geopotential model GO_CONS_GCF_2_TIM_R5. To compensate for the missing gravity data in the target area, we used the surface gravity anomalies extracted from the World Gravity Map 2012. Using 10 Global Navigation Satellite System (GNSS)/levelling data points distributed over Uganda, the RMS fit of the gravimetric geoid model before and after a 4-parameter fit is 11 cm and 7 cm respectively. These results show that UGG2014 agrees considerably better with GNSS/levelling than any other recent regional/ global gravimetric geoid model. The results also emphasize the significant contribution of the GOCE satellite mission to the gravity field recovery, especially for areas with very limited terrestrial gravity data.With an RMS of 7 cm, UGG2014 is a significant step forward in the modelling of a “1-cm geoid” over Uganda despite the poor quality and quantity of the terrestrial gravity data used for its computation.

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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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Feasible Multiple Satellite Mission Scenarios Flying in a Constellation for Refinement of the Gravity Field Recovery

International Journal of Geosciences ◽

10.4236/ijg.2014.53027 ◽

2014 ◽

Vol 05 (03) ◽

pp. 267-273 ◽

Cited By ~ 3

Author(s):

Basem Elsaka

Keyword(s):

Gravity Field ◽

Satellite Mission ◽

Gravity Field Recovery

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Global gravity field recovery from the ARISTOTELES satellite mission

Journal of Geophysical Research Atmospheres ◽

10.1029/93jb02969 ◽

1994 ◽

Vol 99 (B2) ◽

pp. 2841-2851 ◽

Cited By ~ 8

Author(s):

P. N. A. M. Visser ◽

K. F. Wakker ◽

B. A. C. Ambrosius

Keyword(s):

Gravity Field ◽

Satellite Mission ◽

Gravity Field Recovery ◽

Global Gravity ◽

Global Gravity Field Recovery

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Instrument Data Simulations for GRACE Follow-on: Observation and Noise Models

10.5194/essd-2017-45 ◽

2017 ◽

Author(s):

Neda Darbeheshti ◽

Henry Wegener ◽

Vitali Müller ◽

Majid Naeimi ◽

Gerhard Heinzel ◽

...

Keyword(s):

Gravity Field ◽

Simulated Data ◽

Laser Interferometry ◽

Scientific Basis ◽

Satellite Mission ◽

Earth’S Gravity Field ◽

Gravity Field Recovery ◽

Grace Data ◽

Data Files ◽

Grace Mission

Abstract. The Gravity Recovery and Climate Experiment (GRACE) mission has yielded data on the Earth's gravity field to monitor temporal changes for more than fifteen years now. The GRACE twin satellites use microwave ranging with micrometer precision to measure distance variations between two satellites caused by the Earth's global gravitational field. GRACE Follow-on (GRACE-FO) will be the first satellite mission to use inter-satellite laser interferometry in space. The laser ranging instrument (LRI) will provide two additional measurements compared to the GRACE mission: interferometric inter-satellite ranging with nanometer precision and inter-satellite pointing information. We have designed a set of simulated GRACE-FO data, which include LRI measurements, apart from all other GRACE instrument data needed for the Earth's gravity field recovery. The simulated data files are publicly available via https://doi.org/10.22027/AMDC2 and can be used to derive gravity field solutions like from GRACE data. This paper describes the scientific basis and technical approaches used to simulate the GRACE-FO instrument data.

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V04 Level-1 data processing status for GRACE and GRACE Follow-On

10.5194/egusphere-egu2020-10626 ◽

2020 ◽

Author(s):

Tamara Bandikova ◽

Hui Ying Wen ◽

Meegyeong Paik ◽

William Bertiger ◽

Mark Miller ◽

...

Keyword(s):

Data Processing ◽

Gravity Field ◽

Attitude Determination ◽

Precise Orbit Determination ◽

Sensor Data ◽

Satellite Mission ◽

Gravity Field Recovery ◽

Grace Data ◽

Level 1 ◽

Gravity Recovery

<p>On May 22, 2020, the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO), will celebrate two years of successful in-orbit operation. The primary goal of this satellite mission is to provide information about time variations of the Earth&#8217;s gravity field. This is possible due to precise orbit determination and inter-satellite ranging by determining the relative clock alignment of the USOs, precise attitude determination and accelerometry. High quality satellite observations are one of the fundamental requirements for successful gravity field recovery. NASA/Caltech Jet Propulsion Laboratory is the official Level-1 data processing and analysis center. The GRACE-FO Level-1 data are currently being processed with software version V04. This software will be used also for final reprocessing of the GRACE (2002-2017) Level-1 data. Here we present the analysis of two years of GRACE-FO sensor data as well as a preview of the reprocessed GRACE data, and discuss the measurement performance.</p>

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A New Approach to Earth’s Gravity Field Modeling Using GPS-Derived Kinematic Orbits and Baselines

Remote Sensing ◽

10.3390/rs11141728 ◽

2019 ◽

Vol 11 (14) ◽

pp. 1728 ◽

Cited By ~ 3

Author(s):

Xiang Guo ◽

Qile Zhao

Keyword(s):

Gravity Field ◽

Satellite Mission ◽

Earth’S Gravity Field ◽

New Approach ◽

Gravity Field Recovery ◽

Field Modeling ◽

Reference Satellite ◽

Gravity Field Modeling ◽

Grace Satellites ◽

Baseline Approach

Earth’s gravity field recovery from GPS observations collected by low earth orbiting (LEO) satellites is a well-established technique, and kinematic orbits are commonly used for that purpose. Nowadays, more and more satellites are flying in close formations. The GPS-derived kinematic baselines between them can reach millimeter precision, which is more precise than the centimeter-level kinematic orbits. Thus, it has long been expected that the more precise kinematic baselines can deliver better gravity field solutions. However, this expectation has not been met yet in practice. In this study, we propose a new approach to gravity field modeling, in which kinematic orbits of the reference satellite and baseline vectors between the reference satellite and its accompanying satellite are jointly inverted. To validate the added value, data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission are used. We derive kinematic orbits and inter-satellite baselines of the twin GRACE satellites from the GPS data collected in the year of 2010. Then two sets of monthly gravity field solutions up to degree and order 60 are produced. One is derived from kinematic orbits of the twin GRACE satellites (‘orbit approach’). The other is derived from kinematic orbits of GRACE A and baseline vectors between GRACE A and B (‘baseline approach’). Analysis of observation postfit residuals shows that noise in the kinematic baselines is notably lower than the kinematic orbits by 50, 47 and 43% for the along-track, cross-track and radial components, respectively. Regarding the gravity field solutions, analysis in the spectral domain shows that noise of the gravity field solutions beyond degree 10 can be significantly reduced when the baseline approach is applied, with cumulative errors up to degree 60 being reduced by 34%, when compared to the orbit approach. In the spatial domain, the recovered mass changes with the baseline approach are more consistent with those inferred from the K-Band Ranging based solutions. Our results demonstrate that the proposed baseline approach is able to provide better gravity field solutions than the orbit approach. The findings may facilitate, among others, bridging the gap between GRACE and GRACE Follow-On satellite mission.

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Instrument data simulations for GRACE Follow-on: observation and noise models

Earth System Science Data ◽

10.5194/essd-9-833-2017 ◽

2017 ◽

Vol 9 (2) ◽

pp. 833-848 ◽

Cited By ~ 5

Author(s):

Neda Darbeheshti ◽

Henry Wegener ◽

Vitali Müller ◽

Majid Naeimi ◽

Gerhard Heinzel ◽

...

Keyword(s):

Gravity Field ◽

Simulated Data ◽

Laser Interferometry ◽

Scientific Basis ◽

Satellite Mission ◽

Earth’S Gravity Field ◽

Gravity Field Recovery ◽

Grace Data ◽

Data Files ◽

Grace Mission

Abstract. The Gravity Recovery and Climate Experiment (GRACE) mission has yielded data on the Earth's gravity field to monitor temporal changes for more than 15 years. The GRACE twin satellites use microwave ranging with micrometre precision to measure the distance variations between two satellites caused by the Earth's global gravitational field. GRACE Follow-on (GRACE-FO) will be the first satellite mission to use inter-satellite laser interferometry in space. The laser ranging instrument (LRI) will provide two additional measurements compared to the GRACE mission: interferometric inter-satellite ranging with nanometre precision and inter-satellite pointing information. We have designed a set of simulated GRACE-FO data, which include LRI measurements, apart from all other GRACE instrument data needed for the Earth's gravity field recovery. The simulated data files are publicly available via https://doi.org/10.22027/AMDC2 and can be used to derive gravity field solutions like from GRACE data. This paper describes the scientific basis and technical approaches used to simulate the GRACE-FO instrument data.

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Earth’s Time-Variable Gravity from GRACE Follow-On K-Band Range-Rates and Pseudo-Observed Orbits

Remote Sensing ◽

10.3390/rs13091766 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1766

Author(s):

Igor Koch ◽

Mathias Duwe ◽

Jakob Flury ◽

Akbar Shabanloui

Keyword(s):

Gravity Field ◽

Time Variable ◽

Time Variable Gravity ◽

Gravity Field Recovery ◽

Variable Gravity ◽

Earth’S System ◽

Grace Mission ◽

Insight Into ◽

K Band

During its science phase from 2002–2017, the low-low satellite-to-satellite tracking mission Gravity Field Recovery And Climate Experiment (GRACE) provided an insight into Earth’s time-variable gravity (TVG). The unprecedented quality of gravity field solutions from GRACE sensor data improved the understanding of mass changes in Earth’s system considerably. Monthly gravity field solutions as the main products of the GRACE mission, published by several analysis centers (ACs) from Europe, USA and China, became indispensable products for quantifying terrestrial water storage, ice sheet mass balance and sea level change. The successor mission GRACE Follow-On (GRACE-FO) was launched in May 2018 and proceeds observing Earth’s TVG. The Institute of Geodesy (IfE) at Leibniz University Hannover (LUH) is one of the most recent ACs. The purpose of this article is to give a detailed insight into the gravity field recovery processing strategy applied at LUH; to compare the obtained gravity field results to the gravity field solutions of other established ACs; and to compare the GRACE-FO performance to that of the preceding GRACE mission in terms of post-fit residuals. We use the in-house-developed MATLAB-based GRACE-SIGMA software to compute unconstrained solutions based on the generalized orbit determination of 3 h arcs. K-band range-rates (KBRR) and kinematic orbits are used as (pseudo)-observations. A comparison of the obtained solutions to the results of the GRACE-FO Science Data System (SDS) and Combination Service for Time-variable Gravity Fields (COST-G) ACs, reveals a competitive quality of our solutions. While the spectral and spatial noise levels slightly differ, the signal content of the solutions is similar among all ACs. The carried out comparison of GRACE and GRACE-FO KBRR post-fit residuals highlights an improvement of the GRACE-FO K-band ranging system performance. The overall amplitude of GRACE-FO post-fit residuals is about three times smaller, compared to GRACE. GRACE-FO post-fit residuals show less systematics, compared to GRACE. Nevertheless, the power spectral density of GRACE-FO and GRACE post-fit residuals is dominated by similar spikes located at multiples of the orbital and daily frequencies. To our knowledge, the detailed origin of these spikes and their influence on the gravity field recovery quality were not addressed in any study so far and therefore deserve further attention in the future. Presented results are based on 29 monthly gravity field solutions from June 2018 until December 2020. The regularly updated LUH-GRACE-FO-2020 time series of monthly gravity field solutions can be found on the website of the International Centre for Global Earth Models (ICGEM) and in LUH’s research data repository. These operationally published products complement the time series of the already established ACs and allow for a continuous and independent assessment of mass changes in Earth’s system.

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