The GeoForschungsZentrum Potsdam/Groupe de Recherche de Gèodésie Spatiale satellite-only and combined gravity field models: EIGEN-GL04S1 and EIGEN-GL04C

Förste, Christoph; Schmidt, Roland; Stubenvoll, R.; Flechtner, Frank; Meyer, Ulrich; König, Rolf; Neumayer, H.; Biancale, R.; Lemoine, Jean‐Michel; Bruinsma, Sean; Loyer, S.; Barthelmes, Franz; Esselborn, Saskia

doi:10.1007/s00190-007-0183-8

Cited by 209 publications

(144 citation statements)

References 26 publications

(28 reference statements)

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“…The EIGEN-GL04C geoid model (Forste et al, 2008) was used to correct measured ellipsoidal elevation to the height above the geoid, which was then subtracted from the ice thickness to determine ice draft. The shelf ice rises and falls with the ocean tides, which were not corrected for in this study.…”

Section: Uncertaintiesmentioning

confidence: 99%

Seabed topography beneath Larsen C Ice Shelf from seismic soundings

et al. 2014

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Abstract. Seismic reflection soundings of ice thickness and seabed depth were acquired on the Larsen C Ice Shelf in order to test a sub-ice shelf bathymetry model derived from the inversion of IceBridge gravity data. A series of lines was collected, from the Churchill Peninsula in the north to the Joerg Peninsula in the south, and also towards the ice front. Sites were selected using the bathymetry model derived from the inversion of free-air gravity data to indicate key regions where sub-ice shelf oceanic circulation may be affected by ice draft and seabed depth. The seismic velocity profile in the upper 100 m of firn and ice was derived from shallow refraction surveys at a number of locations. Measured temperatures within the ice column and at the ice base were used to define the velocity profile through the remainder of the ice column. Seismic velocities in the water column were derived from previous in situ measurements. Uncertainties in ice and water cavity thickness are in general <10 m. Compared with the seismic measurements, the rootmean-square error in the gravimetrically derived bathymetry at the seismic sites is 162 m. The seismic profiles prove the non-existence of several bathymetric features that are indicated in the gravity inversion model, significantly modifying the expected oceanic circulation beneath the ice shelf. Similar features have previously been shown to be highly significant in affecting basal melt rates predicted by ocean models. The discrepancies between the gravity inversion results and the seismic bathymetry are attributed to the assumption of uniform geology inherent in the gravity inversion process and also the sparsity of IceBridge flight lines. Results indicate that care must be taken when using bathymetry models derived by the inversion of free-air gravity anomalies. The bathymetry results presented here will be used to improve existing sub-ice shelf ocean circulation models.

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Section: Uncertaintiesmentioning

confidence: 99%

Seabed topography beneath Larsen C Ice Shelf from seismic soundings

et al. 2014

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“…Models inferred from the GRACE Ka-band ranging data as well as the continuous 3-D tracking by means of GPS gained approximately two orders of magnitude in accuracy (1 cm geoid error at degree 100) as compared to GRIM5-S1. State-of-the-art models determined with five or more years of GRACE data achieve a maximum degree of the expansion of 150 to 180 (Tapley et al 2007;Förste et al 2008a;Jäggi et al 2009;Mayer-Gürr et al 2010a).…”

Section: Introductionmentioning

confidence: 99%

First GOCE gravity field models derived by three different approaches

Pail¹,

Bruinsma²,

Migliaccio

et al. 2011

J Geod

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Abstact.Three gravity field models, parameterized in terms of spherical harmonic coefficients, have been computed from 71 days of GOCE (Gravity field and steady-state Ocean Circulation Explorer) orbit and gradiometer data by applying independent gravity field processing methods. These gravity models are one major output of the European Space Agency (ESA) project GOCE High-Level Processing Facility (HPF). The processing philosophies and architectures of these three complementary methods are presented and discussed, emphasizing the specific features of the three approaches. The resulting GOCE gravity field models, representing the first models containing the novel measurement type of gravity gradiometry ever computed, are analyzed and assessed in detail. Together with the coefficient estimates, full variance-covariance matrices provide error information about the coefficient solutions. A comparison with state-of-the-art GRACE and combined gravity field models reveals the additional contribution of GOCE based on only 71 days of data. Compared to combined gravity field models, large deviations appear in regions where the terrestrial gravity data are known to be of low accuracy. The GOCE performance, assessed against the GRACE-only model ITGGrace2010s, becomes superior at degree 150, and beyond. GOCE provides significant additional information of the global Earth gravity field, with an accuracy of the 2-months GOCE gravity field models of 10 cm in terms of geoid heights, and 3 mGal in terms of gravity anomalies, globally at a resolution of 100 km (degree/order 200).

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“…Additional background models applied during simulation included a static gravity model (EIGEN-GL04C (Förste et al 2008, used up to degree and order 100), Sun and Moon ephemerides (DE405, Standish 1998), ocean tides (the 8 main constituents Q1, O1, P1, K1, N2, M2, S2 and K2 of EOT08a, Savcenko et al 2008), and non-tidal mass variations in atmosphere, oceans, hydrology, ice, and solid Earth (called AOHIS in the following) from the updated ESA Earth System Model (Dobslaw et al 2015a, used up to degree and order 100). The high-low SST GPS phase and code observations, used to define a reference frame for LEO orbit integration (Reigber et al 2005) have been simulated with white noise of 0.3 and 30 cm, respectively.…”

Section: Simulation Assumptions and Strategymentioning

confidence: 99%

What Can be Expected from the GRACE-FO Laser Ranging Interferometer for Earth Science Applications?

et al. 2015

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The primary objective of the Gravity Recovery and Climate Experiment follow-on (GRACE-FO) satellite mission, due for launch in August 2017, is to continue the GRACE time series of global monthly gravity field models. For this, evolved versions of the GRACE microwave instrument (MWI), GPS-receiver, and accelerometer will be used. A secondary objective is to demonstrate the effectiveness of a laser ranging interferometer (LRI) in improving the satellite-to-satellite tracking measurement performance. In order to investigate the expected enhancement for Earth science applications we have performed a full-scale simulation over the nominal mission lifetime of five years using a realistic orbit scenario and error assumptions both for instrument and background model errors.Unfiltered differences between the synthetic input and the finally recovered time-variable monthly gravity models show notable improvements with the LRI, on global scale, of the order of 23%. The gain is realized for wavelengths smaller than 240 km in case of Gaussian filtering but decreases to just a few percent when anisotropic filtering is applied. This is also confirmed for some typical regional Earth science applications which show randomly distributed patterns of small improvements but also degradations when using DDK4 filtered LRI based models.Analysis of applied error models indicates that accelerometer noise followed by ocean tide and non-tidal mass variation errors are the main contributors to the overall GRACE-FO gravity model error. Improvements in these fields are therefore necessary, besides optimized constellations, to make use of the increased LRI accuracy and to significantly improve gravity field models from Next Generation Gravity Missions.

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The GeoForschungsZentrum Potsdam/Groupe de Recherche de Gèodésie Spatiale satellite-only and combined gravity field models: EIGEN-GL04S1 and EIGEN-GL04C

Cited by 209 publications

References 26 publications

Seabed topography beneath Larsen C Ice Shelf from seismic soundings

Seabed topography beneath Larsen C Ice Shelf from seismic soundings

First GOCE gravity field models derived by three different approaches

What Can be Expected from the GRACE-FO Laser Ranging Interferometer for Earth Science Applications?

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