Error assessment of GOCE SGG data using along track interpolation

Bouman, J; Koop, R.

doi:10.5194/adgeo-1-27-2003

Cited by 16 publications

(13 citation statements)

References 2 publications

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“…Albertella et al 2000;Jarecki et al 2006;Jarecki and Müller 2007). Bouman and Koop (2003b) used along-track interpolation of GGs, which seems to be an adequate tool for error assessment in the MB. The steps for GG preprocessing are (1) correction for temporal gravity field variations; (2) outlier detection and flagging; (3) external calibration and error assessment.…”

Section: Gravity Gradient Preprocessingmentioning

confidence: 99%

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

Bouman

Rispens

Gruber

et al. 2008

J Geod

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One of the products derived from the gravity field and steady-state ocean circulation explorer (GOCE) observations are the gravity gradients. These gravity gradients are provided in the gradiometer reference frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. To use these gravity gradients for application in Earth scienes and gravity field analysis, additional preprocessing needs to be done, including corrections for temporal gravity field signals to isolate the static gravity field part, screening for outliers, calibration by comparison with existing external gravity field information and error assessment. The temporal gravity gradient corrections consist of tidal and nontidal corrections. These are all generally below the gravity gradient error level, which is predicted to show a 1/ f behaviour for low frequencies. In the outlier detection, the 1/ f error is compensated for by subtracting a local median from the data, while the data error is assessed using the median absolute deviation. The local median acts as a high-pass filter and it is robust as is the median absolute deviation. Three different methods have been implemented for the calibration of the gravity gradients. All three methods use a high-pass filter to compensate for the 1/ f gravity gradient error. The baseline method uses state-of-the-art global gravity field models and the most accurate results are obtained if star sensor misalignments are estimated along with the calibration parameters. A second calibration method uses GOCE GPS data to estimate a low-degree gravity field model as well as gravity gradient scale factors. Both methods allow to estimate gravity gradient scale factors down to the 10 −3 level. The third calibration method uses high accurate terrestrial gravity data in selected regions to validate the gravity gradient scale factors, focussing on the measurement band. Gravity gradient scale factors may be estimated down to the 10 −2 level with this method.

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Section: Gravity Gradient Preprocessingmentioning

confidence: 99%

“…In this paper, we present the GOCE gravity gradient preprocessing algorithms as they are implemented in the HPF. Partially, these algorithms have been presented earlier (Bouman and Koop 2003b;, but a complete presentation of the preprocessing has not been given so far.…”

Section: Introductionmentioning

confidence: 99%

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

Bouman

Rispens

Gruber

et al. 2008

J Geod

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“…Also outliers that may occur in the GOCE gravitational gradients need to be searched for and detected in the preprocessing step . Along with the external calibration of the gravitational gradients , their error needs to be assessed (Bouman and Koop 2003). The steps for GG preprocessing therefore are 1.…”

Section: Preprocessing At the High-level Processing Facilitymentioning

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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“…Eshagh and Ebadi (2014) presented a method for error calibration of some GOCE EGMs based on condition adjustment models. b) On board validation of GOCE data Bouman et al (2003) has set up a calibration model based on the instrument (gradiometer) characteristics to validate the SGG data. Bouman and Koop (2003) presented an along-track interpolation method to detect the outliers.…”

mentioning

confidence: 99%

“…b) On board validation of GOCE data Bouman et al (2003) has set up a calibration model based on the instrument (gradiometer) characteristics to validate the SGG data. Bouman and Koop (2003) presented an along-track interpolation method to detect the outliers. Their idea is to compare the along-track interpolated gradients with measured gradients.…”

mentioning

confidence: 99%

Deterministically-Modified Integral Estimators of Gravitational Tensor

Romeshkani

Eshagh

2015

Bol. Ciênc. Geod.

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The Earth's global gravity field modelling is an important subject in Physical Geodesy. For this purpose different satellite gravimetry missions have been designed and launched. Satellite gravity gradiometry (SGG) is a technique to measure the second-order derivatives of the gravity field. The gravity field and steady state ocean circulation explorer (GOCE) is the first satellite mission which uses this technique and is dedicated to recover Earth's gravity models (EGMs) up to medium wavelengths. The existing terrestrial gravimetric data and EGM scan be used for validation of the GOCE data prior to their use. In this research, the tensor of gravitation in the local north-oriented frame is generated using deterministicallymodified integral estimators involving terrestrial data and EGMs. The paper presents that the SGG data is assessable with an accuracy of 1-2 mE in Fennoscandia using a modified integral estimatorby the Molodensky method. A degree of modification of 100 and an integration cap size of 2.5 o for integrating 55   terrestrial data are proper parameters for the estimator.

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Error assessment of GOCE SGG data using along track interpolation

Cited by 16 publications

References 2 publications

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

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

GOCE gravitational gradients along the orbit

Deterministically-Modified Integral Estimators of Gravitational Tensor

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