Benchmark data for verifying background model implementations in orbit and gravity field determination software

Lasser, Martin; Meyer, Ulrich; Jäggi, Adrian; Mayer‐Gürr, Torsten; Kvas, Andreas; Neumayer, Karl Hans; Dahle, Christoph; Flechtner, Frank; Lemoine, Jean‐Michel; Koch, Igor; Weigelt, Matthias; Flury, Jakob

doi:10.5194/adgeo-55-1-2020

Cited by 3 publications

(2 citation statements)

References 25 publications

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“…We hope, in this way, to precisely quantify the impact of model's temporal resolution with the final orbit differences, see Figure 12. In addition, the effect of atmosphere tidal constitutes

S_{1}

and

S_{2}

are provided as benchmarks, since the atmospheric tides are usually assumed as the smallest force model that has to be considered in the precise orbit determination (POD) as well as precise temporal gravity determination (see Lasser et al., 2020).…”

Section: Resultsmentioning

confidence: 99%

A New 1‐Hourly ERA5‐Based Atmosphere De‐Aliasing Product for GRACE, GRACE‐FO, and Future Gravity Missions

et al. 2021

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The current state‐of‐the‐art of satellite gravity data processing makes use of de‐aliasing products to reduce high‐frequency mass anomalies. For example, the most recent official Atmosphere and Ocean De‐aliasing products (AOD1B‐RL06) are applied for the Gravity Recovery and Climate Experiment (GRACE) and GRACE‐Follow On (GRACE‐FO) missions. The temporal resolution of AOD1B‐RL06 is 3 h, and spectrally, they are computed up to degree and order 180. In this study, we explore a refined, e.g., geometrically, physically, and numerically improved, mass integration approach that is important for computing the atmosphere part of these products. Besides, the newly available ERA5 climate data are used to produce a new set of non‐tidal atmosphere de‐aliasing product (HUST‐ERA5) that is computed hourly up to degree and order 100, covering 2002 onwards. Despite an overall agreement with AOD1B‐RL06 (correlation≥0.99), considerable discrepancies still exist between HUST‐ERA5 and AOD1B‐RL06. The possible reasons are therefore analyzed, and we find the input climate data, sampling rate and integration method may result in a product difference of ∼0.3, ∼0.15 and ∼0.05 millimeter geoid height, respectively. The total differences between HUST‐ERA5 and AOD1B‐RL06 can lead to a mean variation of ∼7.34 nm00/s on the laser ranging interferometry (LRI) range‐rate residuals, for example, during January 2019, which is already close to the LRI precision. This impact is invisible for the GRACE (‐FO) gravity inversion because of the less accurate on‐board KBR (K‐band ranging) instrument, however, it will be non‐negligible and should be considered when the LRI completely replaces the KBR in the future gravity missions.

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“…We hope, in this way, to precisely quantify the impact of model's temporal resolution with the final orbit differences, see Figure 12. In addition, the effect of atmosphere tidal constitutes

S_{1}

and

S_{2}

Section: Resultsmentioning

confidence: 99%

A New 1‐Hourly ERA5‐Based Atmosphere De‐Aliasing Product for GRACE, GRACE‐FO, and Future Gravity Missions

et al. 2021

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“…The force modeling implementations were evaluated in a software comparison in the framework of COST-G. Implementations of all separate force effects agree well with the implementations of the COST-G ACs. The differences with regard to the implementations of other ACs are several orders of magnitude below 10 −10 m/s 2 [59]. • Arc length-The 3 h arc length employed in our approach differs considerably from the approaches of other ACs.…”

Section: Processing Detailsmentioning

confidence: 95%

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

Koch¹,

Duwe²,

Flury³

et al. 2021

Remote Sensing

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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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EPOS-OC, a Universal Software Tool for Satellite Geodesy at GFZ

Neumayer,

Schreiner,

König

et al. 2024

International Association of Geodesy Symposia

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The adjustment of parameters from different observations describing the state and change of system Earth has been conducted at the Helmholtz Centre Potsdam—GFZ German Research Centre for Geosciences via satellite observations for many decades. Satellite Laser Ranging (SLR) is used to establish ground station coordinates and their drifts as well as Earth Rotation Parameters (ERPs). Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), Global Navigation Satellite System (GNSS), SLR and Very Long Baseline Interferometry (VLBI) observations are combined to contribute to the development of an International Terrestrial Reference Frame (ITRF) with the highest precision possible. The Earth’s gravity field and its temporal variations are adjusted analyzing orbit perturbations of Low Earth Orbiting (LEO) satellites, where the corresponding trajectories are obtained from Global Positioning System (GPS), on-board accelerometers (ACC) or gradiometers, star tracker (STR) and inter-satellite ranging observations. Apart from real data analysis, numerous simulation studies are conducted, e.g. to investigate the performance of Next Generation Gravity Missions or possible improvements of terrestrial reference frames by space-tie satellites. Also, we contribute to testing the theory of general relativity by analysing observations of the Laser Geodynamic Satellites (LAGEOS). All that would not be possible without a universal software tool that is central to all these activities. In this paper we give a short overview of our program package Earth Parameter and Orbit System (EPOS) with its core module for precise orbit computation (OC) EPOS-OC. We briefly describe its main features and give examples on Precise Orbit Determination (POD) of Earth satellites, describe how the program is used for determination of ERPs, station coordinates, reference frames and the adjustment of Earth’s gravity field using real-world data and within simulation studies. We finally show that EPOS-OC is also a useful tool to test some predictions of the theory of General Relativity.

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Benchmark data for verifying background model implementations in orbit and gravity field determination software

Cited by 3 publications

References 25 publications

A New 1‐Hourly ERA5‐Based Atmosphere De‐Aliasing Product for GRACE, GRACE‐FO, and Future Gravity Missions

A New 1‐Hourly ERA5‐Based Atmosphere De‐Aliasing Product for GRACE, GRACE‐FO, and Future Gravity Missions

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

EPOS-OC, a Universal Software Tool for Satellite Geodesy at GFZ

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