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Auteur B. Tapley |
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High-frequency signal and noise estimates of CSR GRACE RL04 / J.A. Bonin in Journal of geodesy, vol 86 n° 12 (December 2012)
[article]
Titre : High-frequency signal and noise estimates of CSR GRACE RL04 Type de document : Article/Communication Auteurs : J.A. Bonin, Auteur ; S. Bettadpur, Auteur ; B. Tapley, Auteur Année de publication : 2012 Article en page(s) : pp 1165 - 1177 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] bruit (théorie du signal)
[Termes IGN] données GRACE
[Termes IGN] erreur
[Termes IGN] filtrage du bruit
[Termes IGN] force de gravitation
[Termes IGN] levé gravimétrique
[Termes IGN] rapport signal sur bruit
[Termes IGN] traitement du signalRésumé : (Auteur) A sliding window technique is used to create daily-sampled Gravity Recovery and Climate Experiment (GRACE) solutions with the same background processing as the official CSR RL04 monthly series. By estimating over shorter time spans, more frequent solutions are made using uncorrelated data, allowing for higher frequency resolution in addition to daily sampling. Using these data sets, high-frequency GRACE errors are computed using two different techniques: assuming the GRACE high-frequency signal in a quiet area of the ocean is the true error, and computing the variance of differences between multiple high-frequency GRACE series from different centers. While the signal-to-noise ratios prove to be sufficiently high for confidence at annual and lower frequencies, at frequencies above 3 cycles/year the signal-to-noise ratios in the large hydrological basins looked at here are near 1.0. Comparisons with the GLDAS hydrological model and high frequency GRACE series developed at other centers confirm CSR GRACE RL04’s poor ability to accurately and reliably measure hydrological signal above 3–9 cycles/year, due to the low power of the large-scale hydrological signal typical at those frequencies compared to the GRACE errors. Numéro de notice : A2012-651 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0572-5 Date de publication en ligne : 03/06/2012 En ligne : https://doi.org/10.1007/s00190-012-0572-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32097
in Journal of geodesy > vol 86 n° 12 (December 2012) . - pp 1165 - 1177[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2012121 RAB Revue Centre de documentation En réserve L003 Disponible Reducing errors in the GRACE gravity solutions using regularization / H. Save in Journal of geodesy, vol 86 n° 9 (September 2012)
[article]
Titre : Reducing errors in the GRACE gravity solutions using regularization Type de document : Article/Communication Auteurs : H. Save, Auteur ; S. Bettadpur, Auteur ; B. Tapley, Auteur Année de publication : 2012 Article en page(s) : pp 695 - 711 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] données GRACE
[Termes IGN] gravimétrie
[Termes IGN] harmonique sphérique
[Termes IGN] levé gravimétrique
[Termes IGN] régularisation de TychonoffRésumé : (Auteur) The nature of the gravity field inverse problem amplifies the noise in the GRACE data, which creeps into the mid and high degree and order harmonic coefficients of the Earth’s monthly gravity fields provided by GRACE. Due to the use of imperfect background models and data noise, these errors are manifested as north-south striping in the monthly global maps of equivalent water heights. In order to reduce these errors, this study investigates the use of the L-curve method with Tikhonov regularization. L-curve is a popular aid for determining a suitable value of the regularization parameter when solving linear discrete ill-posed problems using Tikhonov regularization. However, the computational effort required to determine the L-curve is prohibitively high for a large-scale problem like GRACE. This study implements a parameter-choice method, using Lanczos bidiagonalization which is a computationally inexpensive approximation to L-curve. Lanczos bidiagonalization is implemented with orthogonal transformation in a parallel computing environment and projects a large estimation problem on a problem of the size of about 2 orders of magnitude smaller for computing the regularization parameter. Errors in the GRACE solution time series have certain characteristics that vary depending on the ground track coverage of the solutions. These errors increase with increasing degree and order. In addition, certain resonant and near-resonant harmonic coefficients have higher errors as compared with the other coefficients. Using the knowledge of these characteristics, this study designs a regularization matrix that provides a constraint on the geopotential coefficients as a function of its degree and order. This regularization matrix is then used to compute the appropriate regularization parameter for each monthly solution. A 7-year time-series of the candidate regularized solutions (Mar 2003–Feb 2010) show markedly reduced error stripes compared with the unconstrained GRACE release 4 solutions (RL04) from the Center for Space Research (CSR). Post-fit residual analysis shows that the regularized solutions fit the data to within the noise level of GRACE. A time series of filtered hydrological model is used to confirm that signal attenuation for basins in the Total Runoff Integrating Pathways (TRIP) database over 320 km radii is less than 1 cm equivalent water height RMS, which is within the noise level of GRACE. Numéro de notice : A2012-467 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0548-5 Date de publication en ligne : 10/03/2012 En ligne : https://doi.org/10.1007/s00190-012-0548-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31913
in Journal of geodesy > vol 86 n° 9 (September 2012) . - pp 695 - 711[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2012091 RAB Revue Centre de documentation En réserve L003 Disponible Geocenter variations derived from GPS tracking of the GRACE satellites / Z. Kang in Journal of geodesy, vol 83 n° 10 (October 2009)
[article]
Titre : Geocenter variations derived from GPS tracking of the GRACE satellites Type de document : Article/Communication Auteurs : Z. Kang, Auteur ; B. Tapley, Auteur ; J. Chen, Auteur ; John Ries, Auteur ; S. Bettadpur, Auteur Année de publication : 2009 Article en page(s) : pp 895 - 901 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] géocentre
[Termes IGN] GRACE
[Termes IGN] orbite basse
[Termes IGN] orbitographie par GNSS
[Termes IGN] poursuite de satelliteRésumé : (Auteur) Two 4.5-year sets of daily geocenter variations have been derived from GPS-LEO (Low-Earth Orbiter) tracking of the GRACE (Gravity Recovery And Climate Experiment) satellites. The twin GRACE satellites, launched in March 2002, are each equipped with a BlackJack global positioning system (GPS) receiver for precise orbit determination and gravity recovery. Since launch, there have been significant improvements in the background force models used for satellite orbit determination, most notably the model for the geopotential, which has resulted in significant improvements to the orbit determination accuracy. The purpose of this paper is to investigate the potential for determining seasonal (annual and semiannual) geocenter variations using GPS-LEO tracking data from the GRACE twin satellites. Internal comparison between the GRACE-A and GRACE-B derived geocenter variations shows good agreement. In addition, the annual and semiannual variations of geocenter motions determined from this study have been compared with other space geodetic solutions and predictions from geophysical models. The comparisons show good agreement except for the phase of the z-translation component. Copyright Springer Numéro de notice : A2009-428 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0307-4 En ligne : https://doi.org/10.1007/s00190-009-0307-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30059
in Journal of geodesy > vol 83 n° 10 (October 2009) . - pp 895 - 901[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-09091 SL Revue Centre de documentation Revues en salle Disponible Precise orbit determination for the GRACE mission using only GPS data / Z. Kang in Journal of geodesy, vol 80 n° 6 (September 2006)
[article]
Titre : Precise orbit determination for the GRACE mission using only GPS data Type de document : Article/Communication Auteurs : Z. Kang, Auteur ; B. Tapley, Auteur ; S. Bettadpur, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 322 - 331 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] GRACE
[Termes IGN] orbitographie par GNSS
[Termes IGN] positionnement par GPS
[Termes IGN] télémétrie laser sur satelliteRésumé : (Auteur) The GRACE (gravity recovery and climate experiment) satellites, launched in March 2002, are each equipped with a BlackJack GPS onboard receiver for precise orbit determination and gravity field recovery. Since launch, there have been significant improvements in the background force models used for satellite orbit determination, most notably the model for the geopotential. This has resulted in significant improvements to orbit accuracy for very low altitude satellites. The purpose of this paper is to investigate how well the orbits of the GRACE satellites (about 470 km in altitude) can currently be determined using only GPS data and based on the current models and methods. The orbit accuracy is assessed using a number of tests, which include analysis of orbit fits, orbit overlaps, orbit connecting points, satellite Laser ranging residuals and K-band ranging (KBR) residuals. We show that 1-cm radial orbit accuracy for the GRACE satellites has probably been achieved. These precise GRACE orbits can be used for such purposes as improving gravity recovery from the GRACE KBR data and for atmospheric profiling, and they demonstrate the quality of the background force models being used. Copyright Springer Numéro de notice : A2006-417 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0073-5 En ligne : https://doi.org/10.1007/s00190-006-0073-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28141
in Journal of geodesy > vol 80 n° 6 (September 2006) . - pp 322 - 331[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-06081 RAB Revue Centre de documentation En réserve L003 Disponible 266-06082 RAB Revue Centre de documentation En réserve L003 Disponible