GPS-derived orbits for the GOCE satellite

Bock, Heike; Jäggi, Adrian; Meyer, Ulrich; Visser, Pieter; IJssel, José van den; Helleputte, Tom van; Heinze, Markus; Hugentobler, Urs

doi:10.1007/s00190-011-0484-9

Cited by 111 publications

(100 citation statements)

References 27 publications

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“…Figures 5, 6 and 7 show the results obtained for GRACE and GOCE. Figure 8 shows the same investigation carried out with the kinematic orbit for GOCE computed at AIUB (Bock et al 2011). Figures 5, 6, 7, and 8 clearly show that the noise level for the radial component is higher.…”

Section: Orbit Comparisonsmentioning

confidence: 83%

“…and May 2012. The blue solutions are based on the ITSG orbits; the red solutions were computed with kinematic orbits produced at AIUB (Bock et al 2011). Apart from the orbit products, the different solutions are based on the same input data and parameter settings.…”

Section: Gravity Field Resultsmentioning

confidence: 99%

“…State-of-the-art approaches are, for example, given by Bock et al (2011), van den IJssel et al (2015 or Prange (2010). They all rely on observation combinations, which are utilized to mitigate systematic errors like the ionospheric influence.…”

Section: Methodsmentioning

confidence: 99%

“…For the GRACE satellites, the L1B data product GNV1B provided by the Jet Propulsion Laboratory (JPL) (Case et al 2010) was chosen. For GOCE, we used a reduced-dynamic orbit solution produced by the Astronomical Institute at the University of Bern (AIUB) (Bock et al 2011), which is provided in the GOCE level 2 SST_PSO (Gruber et al 2008) product. Daily rms values of filtered position differences between kinematic and reduced-dynamic orbits for GRACE B Fig.…”

Section: Orbit Comparisonsmentioning

confidence: 99%

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Precise orbit determination based on raw GPS measurements

Zehentner

Mayer‐Gürr

2015

J Geod

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Precise orbit determination is an essential part of the most scientific satellite missions. Highly accurate knowledge of the satellite position is used to geolocate measurements of the onboard sensors. For applications in the field of gravity field research, the position itself can be used as observation. In this context, kinematic orbits of low earth orbiters (LEO) are widely used, because they do not include a priori information about the gravity field. The limiting factor for the achievable accuracy of the gravity field through LEO positions is the orbit accuracy. We make use of raw global positioning system (GPS) observations to estimate the kinematic satellite positions. The method is based on the principles of precise point positioning. Systematic influences are reduced by modeling and correcting for all known error sources. Remaining effects such as the ionospheric influence on the signal propagation are either unknown or not known to a sufficient level of accuracy. These effects are modeled as unknown parameters in the estimation process. The redundancy in the adjustment is reduced; however, an improvement in orbit accuracy leads to a better gravity field estimation. This paper describes our orbit determination approach and its mathematical background. Some examples of real data applications highlight the feasibility of the orbit determination method based on raw GPS measurements. Its suitability for gravity field estimation is presented in a second step. B Norbert Zehentner

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Section: Orbit Comparisonsmentioning

confidence: 83%

Section: Gravity Field Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Orbit Comparisonsmentioning

confidence: 99%

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Precise orbit determination based on raw GPS measurements

Zehentner

Mayer‐Gürr

2015

J Geod

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“…It is assumed that the GPS SST observations are first reduced to a time series of highly accurate Cartesian X , Y and Z coordinates in an Earth-centred, pseudo-inertial reference frame. For GOCE, these time series are obtained from a kinematic orbit determination (Bock et al 2010). These time series then serve as observables for the first module.…”

Section: Validation Of Gradiometer Observations By Gpsmentioning

confidence: 99%

GOCE gravitational gradients along the orbit

Bouman¹,

Fiorot

Fuchs³

et al. 2011

J Geod

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GOCE is ESA's gravity field mission and the first satellite ever that measures gravitational gradients in space, that is, the second spatial derivatives of the Earth's gravitational potential. The goal is to determine the Earth's mean gravitational field with unprecedented accuracy at spatial resolutions down to 100 km. GOCE carries a gravity gradiometer that allows deriving the gravitational gradients with very high precision to achieve this goal. There are two types of GOCE Level 2 gravitational gradients (GGs) along the orbit: the gravitational gradients in the gradiometer reference frame (GRF) and the gravitational gradients in the local north oriented frame (LNOF) derived from the GGs in the GRF by point-wise rotation. Because the V X X , V Y Y , V Z Z and V X Z are much more accurate than V XY and V Y Z , and because the error of the accurate GGs increases for low frequencies, the rotation requires that part of the measured GG signal is replaced by model signal. However, the actual quality of the gradients in GRF and LNOF needs to be assessed. We analysed the outliers in the GGs, validated the GGs in the GRF using independent gravity field information and compared their assessed error with the requirements. In addition, we compared the GGs in the LNOF with state-of-the-art global gravity field models and determined the model contribution to the rotated GGs. We found that the percentage of detected outliers is below 0.1% for all GGs, and external gravity data confirm that the GG scale factors do not differ from one down to the 10 −3 level. Furthermore, we found that the error of V X X and V Y Y is approximately at the level of the requirement on the gravitational gradient trace, whereas the V Z Z error is a factor of 2-3 above the requirement for higher frequencies. We show that the model contribution in the rotated GGs is 2-35% dependent on the gravitational gradient. Finally, we found that GOCE gravitational gradients and gradients derived from EIGEN-5C and EGM2008 are consistent over the oceans, but that over the continents the consistency may be less, especially in areas with poor terrestrial gravity data. All in all, our analyses show that the quality of the GOCE gravitational gradients is good and that with this type of data valuable new gravity field information is obtained.

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ESA's satellite‐only gravity field model via the direct approach based on all GOCE data

Bruinsma

Förste

Abrikosov

et al. 2014

Geophysical Research Letters

129

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Gravity field and steady state Ocean Circulation Explorer (GOCE) gravity gradient data of the entire science mission and data from LAGEOS 1/2 and Gravity Recovery and Climate Experiment (GRACE) were combined in the construction of a satellite-only gravity field model to maximum degree 300. When compared to Earth Gravitational Model 2008, it is more accurate at low to medium resolution, thanks to GOCE and GRACE data. When compared to earlier releases of European Space Agency GOCE models, it is more accurate at high degrees owing to the larger amount of data ingested, which was moreover taken at lower altitude. The impact of orbiting at lower altitude in the last year of the mission is large: a model based on data of the last 14 months is significantly more accurate than the release 4 model constructed with the first 28 months. The (calibrated) cumulated geoid error estimate at 100 km resolution is 1.7 cm. The optimal resolution of the GOCE model for oceanographic application is between 100 and 125 km.

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GPS-derived orbits for the GOCE satellite

Cited by 111 publications

References 27 publications

Precise orbit determination based on raw GPS measurements

Precise orbit determination based on raw GPS measurements

GOCE gravitational gradients along the orbit

ESA's satellite‐only gravity field model via the direct approach based on all GOCE data

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