Preprocessing of gravity gradients at the GOCE high-level processing facility

Bouman, J; Rispens, Sietse M.; Gruber, Thomas; Koop, R.; Schrama, Ernst; Visser, Pieter; Tscherning, C. C.; Veicherts, M.

doi:10.1007/s00190-008-0279-9

Cited by 40 publications

(37 citation statements)

References 29 publications

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“…The off-diagonal terms are almost not flagged and the mean of detected outliers is about 6 per week for the V X Z component. Bouman et al (2009) found that for simulated GOCE data the Type I error is 0.02% for the diagonal gravitational gradients and 0.00% for the off-diagonal gravitational gradients. These numbers are very close to what we find here for real data and therefore a large part of the detected outliers is probably a Type I error, that is, the observation is not an outlier but resides in the tail of the distribution.…”

Section: Outlier Detectionmentioning

confidence: 94%

“…The different steps of the GG preprocessing method are summarized in Sect. 2.2, for a detailed description, see (Bouman et al 2009). …”

Section: Preprocessing At the High-level Processing Facilitymentioning

confidence: 99%

“…In our processing chain, a set of gravity potential correction coefficients is computed for every 6 h, which further is used to compute gravitational gradient corrections for all six tensor elements. For a more complete description of the temporal gravity field variations and how they are computed see (Bouman et al 2009). The gravitational gradient temporal gravity field signals are in general very small at GOCE altitude compared with the GG signal and error.…”

Section: Corrections For Temporal Gravity Field Variationsmentioning

confidence: 99%

“…If less than five consecutive epochs are detected as outliers, then the EGG_NOM_2 file will contain a fill-in value, see (Gruber et al 2007). Details on the outlier detection algorithm as well as the performance of the single tests and their combination can be found in Bouman et al 2009). …”

Section: Outlier Detectionmentioning

confidence: 99%

“…2 the preprocessing of the gravitational gradients in the gradiometer reference frame (GRF), which is the instrument frame fixed to the satellite. The method is discussed in detail in (Bouman et al 2009) and is briefly summarized here. We will focus on the results with real data and discuss their performance.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Outlier Detectionmentioning

confidence: 94%

“…The different steps of the GG preprocessing method are summarized in Sect. 2.2, for a detailed description, see (Bouman et al 2009). …”

Section: Preprocessing At the High-level Processing Facilitymentioning

confidence: 99%

Section: Corrections For Temporal Gravity Field Variationsmentioning

confidence: 99%

Section: Outlier Detectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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GOCE gravitational gradients along the orbit

Bouman¹,

Fiorot

Fuchs³

et al. 2011

J Geod

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Antarctic outlet glacier mass change resolved at basin scale from satellite gravity gradiometry

Bouman¹,

Fuchs²,

Ivins

et al. 2014

Geophysical Research Letters

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The orbit and instrumental measurement of the Gravity Field and Steady State Ocean Circulation Explorer (GOCE) satellite mission offer the highest ever resolution capabilities for mapping Earth's gravity field from space. However, past analysis predicted that GOCE would not detect changes in ice sheet mass. Here we demonstrate that GOCE gravity gradiometry observations can be combined with Gravity Recovery and Climate Experiment (GRACE) gravity data to estimate mass changes in the Amundsen Sea Sector. This refined resolution allows land ice changes within the Pine Island Glacier (PIG), Thwaites Glacier, and Getz Ice Shelf drainage systems to be measured at respectively −67 ± 7, −63 ± 12, and −55 ± 9 Gt/yr over the GOCE observing period of November 2009 to June 2012. This is the most accurate pure satellite gravimetry measurement to date of current mass loss from PIG, known as the “weak underbelly” of West Antarctica because of its retrograde bed slope and high potential for raising future sea level.

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Observing coseismic gravity change from the Japan Tohoku‐Oki 2011 earthquake with GOCE gravity gradiometry

Fuchs¹,

Bouman²,

Broerse

et al. 2013

JGR Solid Earth

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The Japan Tohoku‐Oki earthquake (9.0 Mw) of 11 March 2011 has left signatures in the Earth's gravity field that are detectable by data of the Gravity field Recovery and Climate Experiment (GRACE) mission. Because the European Space Agency's (ESA) satellite gravity mission Gravity field and steady‐state Ocean Circulation Explorer (GOCE)—launched in 2009—aims at high spatial resolution, its measurements could complement the GRACE information on coseismic gravity changes, although time‐variable gravity was not foreseen as goal of the GOCE mission. We modeled the coseismic earthquake geoid signal and converted this signal to vertical gravity gradients at GOCE satellite altitude. We combined the single gradient observations in a novel way reducing the noise level, required to detect the coseismic gravity change, subtracted a global gravity model, and applied tailored outlier detection to the resulting gradient residuals. Furthermore, the measured gradients were along‐track filtered using different gradient bandwidths where in the space domain Gaussian smoothing has been applied. One‐year periods before and after earthquake occurrence have been compared with the modeled gradients. The comparison reveals that the earthquake signal is well above the accuracy of the vertical gravity gradients at orbital height. Moreover, the obtained signal from GOCE shows a 1.3 times higher amplitude compared with the modeled signal. Besides the statistical significance of the obtained signal, it has a high spatial correlation of ~0.7 with the forward modeled signal. We conclude therefore that the coseismic gravity change of the Japan Tohoku‐Oki earthquake left a statistically significant signal in the GOCE measured gravity gradients.

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Preprocessing of gravity gradients at the GOCE high-level processing facility

Cited by 40 publications

References 29 publications

GOCE gravitational gradients along the orbit

GOCE gravitational gradients along the orbit

Antarctic outlet glacier mass change resolved at basin scale from satellite gravity gradiometry

Observing coseismic gravity change from the Japan Tohoku‐Oki 2011 earthquake with GOCE gravity gradiometry

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