Mitigation of the current errors in precise orbit determination of altimetry satellites (MEPODAS)
Final Report Abstract
Precise orbits of altimetry satellites are a prerequisite for the precise monitoring of sea level and its changes. Significant progress has been made in improving the quality of satellite orbits over the last 30 years, increasing the radial orbit accuracy from decimetres to centimetres and even sub-centimetres. The aim of MEPODAS was to quantify the remaining errors in state-ofthe-art precise orbit determination (POD) of altimetry satellites, to investigate the impact of different models and parameterizations on POD accuracy, and to find possibilities to further improve the orbit quality of these satellites. Comparisons of contemporary orbit solutions of altimetry satellites indicate that the satellite positions of orbits derived using DORIS and GPS observations agree in the radial direction within 0.4–1.0 cm root-mean-square (RMS) differences for the Jason and Sentinel-3 missions and within 1.9 cm for TOPEX/Poseidon. During the last decade, the standard deviation of radial errors improved from 1.14 cm (GDR-C) to 0.98 cm (POE-F). The sources of the current remaining POD errors are non-linear geodetic station motions, time-varying Earth's gravity, inhomogeneous distribution of SLR stations, and difficulties in modelling non-gravitational forces, for example, satellite self-shadowing and station- and satellite-specific biases. The project showed that in order to further improve the orbit quality, an elaboration of the background models for the POD of altimetry satellites should be further performed, together with possible improvements of the tracking systems. Moreover, to mitigate the current remaining errors in POD of altimetry satellites, regular (at least once every 5–6 years) reprocessing of TRF realizations and Earth's time-variable gravity field models by including all data back to 1992 is required. Estimation of station- and satellite-specific biases in SLR analyses allows, to a certain extent, to mitigate remaining errors. However, care should be taken when estimating arc-wise range biases (RBs) for each station, since some important geophysical information in the radial direction of the orbit system and station heights can be absorbed by frequently (e.g., arc-wise) estimated RBs. The generation of improved models for non-gravitational force modelling, considering self-shadowing effects and thermal dissipation will additionally reduce orbit errors. Additional attempts should be made to reduce geographically correlated errors by making geodetic networks more homogeneous.
Publications
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On the current accuracy of altimetry satellite orbits. Copernicus GmbH.
Rudenko, Sergei; Dettmering, Denise; Bloßfeld, Mathis; Zeitlhöfler, Julian & Alkahal, Riva
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Application of the ITRS2020 realizations for precise orbit determination of SLR and altimetry satellites. IAG International Symposium on Reference Frames for Applications in Geosciences (REFAG 2022), Thessaloniki, Greece, 17-20 October, 2022
Rudenko S., Bloßfeld M., Zeitlhöfler J., Kehm A., Dettmering D., Glomsda M., Angermann D. & Seitz M.
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On the accuracy of contemporary orbits of altimetry satellites in the radial direction. 2022 Ocean Surface Topography Science Team Meeting, Venice, Italy, 31 October 31 – 4 November, 2022
Rudenko S., Dettmering D., Bloßfeld M., Zeitlhöfler J. & Alkahal R.
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Precise orbit determination of SLR and altimetry satellites using ITRS2020 realizations. The 22nd International Workshop on Laser Ranging, Guadalajara, Spain and online, 7-11 November 2022
Rudenko S., Bloßfeld M., Kehm A., Dettmering D., Zeitlhöfler J., Glomsda M., Angermann D. & Seitz M.
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DGFI-TUM DSO1 orbits of altimetry satellites TOPEX/Poseidon, Jason-1, Jason-2 and Jason-3 derived from SLR data in the SLRF2014 reference frame (data). Deutsches Geodätisches Forschungsinstitut, Zenodo
Rudenko S., Zeitlhöfler J. & Bloßfeld M.
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Evaluation of ITRS 2020 realizations for precise orbit determination of altimetry satellites. IDS AWG Meeting, Saint-Mandé, Paris, France, 29 November 2023
Rudenko S., Bloßfeld M., Dettmering D. & Zeitlhöfler J.
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Evaluation of the ITRS 2020 realizations for POD of altimetry satellites. 2023 Ocean Surface Topography Science Team Meeting, San Juan, Puerto Rico, 7-11 November, 2023
Rudenko S., Dettmering D., Bloßfeld M. & Zeitlhöfler J.
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Impact of SLR long-term mean range biases on the orbits of altimetry and SLR satellites for ITRS2020 realizations. Copernicus GmbH.
Rudenko, Sergei; Bloßfeld, Mathis; Zeitlhöfler, Julian; Kehm, Alexander & Dettmering, Denise
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Radial Orbit Errors of Contemporary Altimetry Satellite Orbits. Surveys in Geophysics, 44(3), 705-737.
Rudenko, Sergei; Dettmering, Denise; Zeitlhöfler, Julian; Alkahal, Riva; Upadhyay, Dhruv & Bloßfeld, Mathis
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Results of tests of the Earth‘s mean time-variable gravity field model CNES_GRGS.RL05MF_combined_GRACE_SLR_DORIS using precise orbit determination of TOPEX/Poseidon and Jason satellites. IDS AWG Meeting, online, 18 April 2023
Rudenko S., Alkahal R., Bloßfeld M. & Lemoine J.-M.
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Station-dependent satellite laser ranging measurement corrections for TOPEX/Poseidon. Advances in Space Research, 71(1), 975-996.
Zeitlhöfler, Julian; Bloßfeld, Mathis; Rudenko, Sergei; Dettmering, Denise & Seitz, Florian
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Impact of new Earth’s time-variable gravity field models on orbits of altimetry satellites. Copernicus GmbH.
Rudenko, Sergei; Dettmering, Denise; Bloßfeld, Mathis & Zeitlhöfler, Julian
