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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 36, issue 5 | Copyright

Special issue: Dynamics and interaction of processes in the Earth and its...

Ann. Geophys., 36, 1227-1241, 2018
https://doi.org/10.5194/angeo-36-1227-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regular paper 20 Sep 2018

Regular paper | 20 Sep 2018

PPP-based Swarm kinematic orbit determination

Le Ren and Steffen Schön Le Ren and Steffen Schön
  • Leibniz Universität Hannover, Institut für Erdmessung (IfE), Schneiderberg 50, 30167 Hannover, Germany

Abstract. The Swarm mission of the European Space Agency (ESA) offers excellent opportunities to study the ionosphere and to provide temporal gravity field information for the gap between the Gravity Recovery and Climate Experiment (GRACE) and its follow-on mission (GRACE-FO). In order to contribute to these studies, at the Institut für Erdmessung (IfE) Hannover, a software based on precise point positioning (PPP) batch least-squares adjustment is developed for kinematic orbit determination. In this paper, the main achievements are presented.

The approach for the detection and repair of cycle slips caused by ionospheric scintillation is introduced, which is based on the Melbourne–Wübbena and ionosphere-free linear combination. The results show that around 95% of cycle slips can be repaired and the majority of the cycle slips occur on L2. After the analysis and careful preprocessing of the observations, 1-year kinematic orbits of Swarm satellites from September 2015 to August 2016 are computed with the PPP approach. The kinematic orbits are validated with the reduced-dynamic orbits published by the ESA in the Swarm Level 2 products and SLR measurements. The differences between IfE kinematic orbits and ESA reduced-dynamic orbits are at the 1.5, 1.5 and 2.5cm level in the along-track, cross-track and radial directions, respectively. Remaining systematics are characterized by spectral analyses, showing once-per-revolution period. The external validation with SLR measurements shows RMSEs at the 4cm level. Finally, fully populated covariance matrices of the kinematic orbits obtained from the least-squares adjustment with 30, 10 and 1s data rate are discussed. It is shown that for data rates larger than 10s, the correlation between satellite positions should be taken into account, for example, for the recovery of gravity field from kinematic orbits.

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In this contribution, we analyse the performance of the Swarm onboard GPS receiver and present the approach for determination of the IfE Swarm kinematic orbit with PPP. The differences between our kinematic orbits and ESA reduced-dynamic orbits are at 1.5 cm, 1.5 cm and 2.5 cm level in along-track, cross-track and radial directions, respectively. A comparison with SLR underlines an accuracy of the kinematic orbits of 3–4 cm.
In this contribution, we analyse the performance of the Swarm onboard GPS receiver and present...
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