Download or read book Efficient Global Gravity Field Determination from Satellite to satellite Tracking written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: By the middle of this decade, measurements from the CHAMP (CHAllenging of Minisatellite Payload) and GRACE (Gravity Recovery And Climate Experiment) gravity mapping satellite missions are expected to provide a significant improvement in our knowledge of the Earth's mean gravity field and its temporal variation. For this research, new observation equations and efficient inversion method were developed and implemented for determination of the Earth2s global gravity field using satellite measurements. On the basis of the energy conservation principle, in situ (on-orbit) disturbing potential and potential difference observations were computed using data from accelerometer- and GPS receiver-equipped satellites, such as CHAMP and GRACE. The efficient iterative inversion method provided the exact estimates as well as an approximate, but very accurate error variance-covariance matrix of the least squares system for both satellite missions. The global disturbing potential observable computed using 16-days of CHAMP data was used to determine a gravity field solution (OSU02A), is commensurate in geoid accuracy to other gravity models and yields improvement in the polar region at wavelengths longer than 800 km. The annual variation of Earth's gravitational field was estimated and compared with other solutions from satellite laser ranging analysis. The annual geoid change of 1 mm would be expected mostly due to atmosphere, continental surface water, and ocean mass redistribution. The correlation between CHAMP and SLR solutions was 0.6 to approx 0.8 with 0.7 mm of RMS difference. Based on the monthly GRACE simulation, the geoid was obtained with an accuracy of a few cm and with a resolution (half wavelength) of 160 km. However, the geoid accuracy can become worse by a factor of 7 because of spatial aliasing. The approximate error covariance was found to be a very good accuracy measure of the estimated coefficients, geoid, and gravity anomaly. The resulting recovered temporal gravity fields have about 0.2 mm errors in terms of geoid height with a resolution of 670 km. It was quantified that how significant the effects due to the inherent modeling errors and temporal aliasing caused by ocean tides, atmosphere, and ground surface water mass are on monthly mean GRACE gravity estimates.

Download or read book Global Gravity Field Modeling from Satellite to Satellite Tracking Data written by Majid Naeimi and published by Springer. This book was released on 2017-02-10 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a sound theoretical basis for the the different gravity field recovery methods and the numerics of satellite-to-satellite tracking data. It represents lectures given at the ‘Wilhelm and Else Heraeus Autumn School’ in Bad Honnef, Germany, October 4-9, 2015. The emphasis of the school was on providing a sound theoretical basis for the different gravity field recovery methods and the numerics of data analysis. The approaches covered here are the variational equations (classical approach), the acceleration approach and the energy balance approach, all of which are used for global gravity field recovery on the basis of satellite observations. The theory of parameter estimation in satellite gravimetry and concepts for orbit determination are also included. The book guides readers through a broad range of topics in satellite gravimetry, supplemented by the necessary theoretical background and numerical examples. While it provides a comprehensive overview for those readers who are already familiar with satellite gravity data processing, it also offers an essential reference guide for graduate and undergraduate students interested in this field.

Download or read book Global Gravity Field Recovery from Satellite to satellite Tracking Data with the Acceleration Approach written by Xianglin Liu and published by Netherlands Geodetic Commission. This book was released on 2008 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents Abstract xi Samenvatting xv Curriculum vitae xix Acknowledgements xxii 1. Introduction 1 2. Gravity field modeling from SST data: an overview 9 3. Gravity field modeling from CHAMP data 53 4. Gravity field modeling from GRACE hl-SST data 81 5. Gravity field modeling from GRACE ll-SST data 91 6. Analysis of results obtained from the 3RC approach 133 7. Summary, conclusions and recommendations 203 Bibliography 209 A. Autocorrelation 223 B. Gaussian Filtering 225

Download or read book Global Gravity Field Recovery from Satellite to satellite Tracking with the Acceleration Approach written by Xianglin Liu and published by . This book was released on 2008 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determination of the Geopotential from Satellite to satellite Tracking Data written by Bruce C. Douglas and published by . This book was released on 1980 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Global Gravity Field and Its Temporal Variations written by Richard H. Rapp and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: In July 1995 the XXI General Assembly of the International Union of Geodesy and Geophysics was held in Boulder, Colorado. At this meeting the International Association of Geodesy (lAG) organized a number of symposia to discuss scientific developments and future directions in a number of areas. One of these symposia was G3, Global Gravity Field and Its Temporal Variations. This symposium consisted of four invited and 36 contributed papers. The contributed papers were given as oral or poster presentations. This proceedings volume represents the written contributions of the four invited papers (appearing as the first four papers in the volume) and 19 additional papers. The authors were asked to limit the length of their paper to approximately ten pages, which, in some cases, did limit what an author wanted to say. The papers in this volume have been placed in the same order as they were presented at the ruGG meeting. A key theme of the symposium is given in the paper by Nerem, Klosko, and Pavlis where they discuss applications of gravity field information in geodesy and oceanography. The significant achievements in determining the gravity field in the ocean areas from satellite altimeter data is discussed by Sandwell, Yale, McAdoo, and Smith. A review of time changes of the Earth's gravity field from terrestrial measurements is given by Lambert et aI. , and from satellite perturbation techniques by Eanes and Bettadpur. A description of new geopotential models is given in the paper by Tapley et al.

Download or read book Global Gravity Field Determination Using the GPS Measurements Made Onboard the Low Earth Orbiting Satellite CHAMP written by Lars Prange and published by . This book was released on 2010 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Satellite Orbit Determination and Gravity Field Recovery from Satellite to satellite Tracking written by K. F. Wakker and published by . This book was released on 1989 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geometrical Theory of Satellite Orbits and Gravity Field written by Drazen Svehla and published by Springer. This book was released on 2018-07-02 with total page 537 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book on space geodesy presents pioneering geometrical approaches in the modelling of satellite orbits and gravity field of the Earth, based on the gravity field missions CHAMP, GRACE and GOCE in the LEO orbit. Geometrical approach is also extended to precise positioning in space using multi-GNSS constellations and space geodesy techniques in the realization of the terrestrial and celestial reference frame of the Earth. This book addresses major new developments that were taking place in space geodesy in the last decade, namely the availability of GPS receivers onboard LEO satellites, the multitude of the new GNSS satellite navigation systems, the huge improvement in the accuracy of satellite clocks and the revolution in the determination of the Earth's gravity field with dedicated satellite missions.

Download or read book Theory of Satellite Geodesy and Gravity Field Determination written by Fernando Sansò and published by Springer. This book was released on 1989-09-18 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Observation of the Earth System from Space written by Jakob Flury and published by Springer Science & Business Media. This book was released on 2006-02-28 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the recent years, space-based observation methods have led to a subst- tially improved understanding of Earth system. Geodesy and geophysics are contributing to this development by measuring the temporal and spatial va- ations of the Earth’s shape, gravity ?eld, and magnetic ?eld, as well as at- sphere density. In the frame of the GermanR&D programmeGEOTECHNO- LOGIEN,researchprojectshavebeen launchedin2002relatedto the satellite missions CHAMP, GRACE and ESA’s planned mission GOCE, to comp- mentary terrestrial and airborne sensor systems and to consistent and stable high-precision global reference systems for satellite and other techniques. In the initial 3-year phase of the research programme (2002-2004), new gravity ?eld models have been computed from CHAMP and GRACE data which outperform previous models in accuracy by up to two orders of m- nitude for the long and medium wavelengths. A special highlight is the - termination of seasonal gravity variations caused by changes in continental water masses. For GOCE, to be launched in 2006, new gravity ?eld analysis methods are under development and integrated into the ESA processing s- tem. 200,000 GPS radio occultation pro?les, observed by CHAMP, have been processed on an operational basis. They represent new and excellent inf- mation on atmospheric refractivity, temperature and water vapor. These new developments require geodetic space techniques (such as VLBI, SLR, LLR, GPS) to be combined and synchronized as if being one global instrument.

Download or read book The Study of Factors Affecting the Precise Estimation of the Earth s Gravity Field written by Richard H. Rapp and published by . This book was released on 1981 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes the work done in the three year period of the contract. Brief remarks are made concerning research in the following areas: new analysis techniques for data given on a spherical grid: analysis of satellite-to-satellite tracking data; global gravity field modelling; and the vertical datum problem. A complete list of papers and reports produced under contract sponsorship are listed. (Author).

Download or read book Satellite to Satellite Tracking for Orbit Improvement and Determination of a 1 Degree X 1 Degree Gravity Field written by F. M Loveless (Jr) and published by . This book was released on 1976 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The object of the contract was to investigate satellite-to-satellite tracking for orbit improvement and determination of a 1 degree x 1 degree gravity field using actual GEOS-C data. Studies were conducted at a low level of effort in order to familiarize personnel with the characteristics of the data and to obtain a limited check on the principal analysis. Results of simulations designed to accomplish the goals of the contract are presented. These simulations were made awaiting the launch of GEOS-C and the release of the initial tracking data. GEOS-C state vectors were determined from NSWC 'range difference' data. The vectors are for 13 revolutions observed during the period from 27 April 1975 to 3 May 1975.

Download or read book Satellite Gravity and the Geosphere written by National Research Council and published by National Academies Press. This book was released on 1997-09-02 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the past three decades, it has been possible to measure the earth's static gravity from satellites. Such measurements have been used to address many important scientific problems, including the earth's internal structure, and geologically slow processes like mantle convection. In principle, it is possible to resolve the time-varying component of the gravity field by improving the accuracy of satellite gravity measurements. These temporal variations are caused by dynamic processes that change the mass distribution in the earth, oceans, and atmosphere. Acquisition of improved time-varying gravity data would open a new class of important scientific problems to analysis, including crustal motions associated with earthquakes and changes in groundwater levels, ice dynamics, sea-level changes, and atmospheric and oceanic circulation patterns. This book evaluates the potential for using satellite technologies to measure the time-varying component of the gravity field and assess the utility of these data for addressing problems of interest to the earth sciences, natural hazards, and resource communities.

Download or read book Global Gravity Field Modelling Using Satellite Gravity Gradiometry written by Radboud Koop and published by . This book was released on 1993 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Temporal Gravity Recovery from Satellite to satellite Tracking Using the Acceleration Approach written by Chaoyang Zhang (Ph. D. in geodetic science) and published by . This book was released on 2020 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: The temporal gravity solutions estimated from NASA/DLR’s Gravity Recovery And Climate Experiment (GRACE) mission, and its successor, NASA/GFZ’s GRACE Follow-On (GRACE-FO), manifested as mass transports within the Earth system, have been used for a wide variety of Earth Science and climate change studies since 2002. However, there is an around one-year gap between the two satellite gravity missions (2017-2018). ESA’s fifth Earth Explorer Mission, the Swarm 3-satellite constellation, equipped with geodetic quality GNSS tracking system, was proposed to fill the gravimetry observation climate record data gap, at a moderate spatial resolution. Here, I applied a modified decorrelated acceleration approach to recover temporal gravity field using the 3-satellite Swarm constellation GPS tracking data. This approach is based on the simple linear relation between the second time derivative of the orbit and the gravitational acceleration. However, the time derivative could highly amplify the noise and make the noise correlated. In addtion, GPS positioning also involves correlation noise. Therefore, two linear transformations were introduced to decorrelate the observation noise. Next, two adjustment methods were studied to optimally combine the three gravity components, namely along-track, cross-track, and radial direction, along with introducing relative weights among orbital arcs for the final optimal gravity field estimation. The Swarm-only temporal gravity solutions have a good to excellent agreement with the overlapping GRACE/GRACE-FO solutions at least up to spherical harmonics degree around 13 (~1500 km, half-wavelength). Swarm-only temporal gravity solutions were then used to fill the mass change data gap over Greenland and West Antarctica ice-sheets during 2017-2018. Over Greenland, Swarm observed mass anomalies agreed well within the time epochs that overlaped with GRACE (correlation coefficient (CC) = 0.62), and GRACE-FO (CC=0.78). Within the data gap year, Swarm observed mass anomalies were relatively small suggesting that the Greenland mass loss slowed down, where the estimated short-term linear trend dropped from -54.3 ± 1.9 mm/yr (2013-2016 from GRACE) to -13.3 ± 7.5 mm/yr (2016-2018 from Swarm). In addition, as compared with the relatively quiet 2015-2017 at 13.5 ± 14.7 mm/yr, Swarm observed a fast ice mass loss episode at -89.2 ± 9.4 mm/yr during the gap year over West Antarctica, which agreed well with the estimate from GRACE and GRACE-FO without considering the gap at -92.8 ± 2.8 mm/yr during 2017-2019. This fast mass loss episode observed by Swarm also supports that the offset between GRACE and GRACE-FO time series is indeed due to mass loss but not a systematic bias. The official GRACE/GRACE-FO gravity products are derived from K-/Ka Band range (KBR) rate observations. Alternatively, the range acceleration observations could be used to estimate temporal gravity based on the so-called acceleration approach. In this study, by means of satellite orbit refinement, novel error mitigation schemes, and proper stochastic model estimation, the representation of range accelration was significantly improved in the acceleration equation (admittance spectrum dropped from up to 7 to around 1), and the in-situ line-of-sight gravity difference (LOSGD) was estimated with a high fidelity (CC = 0.96 with Level 2 data predicted LOSGD). For the first time, the improved acceleration approach was implemented for global temporal gravity recovery using GRACE and GRACE-FO observed range accelerations. The temporal gravity solutions recovered using this approach are, in general, in good agreement with the GRACE official Level 2 data products, based on the comparisons of the global mass variation trends, and basin-scale mass anomalies times series. Particularly, the gravity solution correlations between solutions in this study and other solutions are higher during the GRACE-FO time span. Despite the loss of an accelerometer onboard one of the GRACE-FO satellites, this closer comparison could be attributable to the improved range observation quality and the reduced noise level, which is clearly shown in the gravity inversion formal error. Because the high-low GPS tracking data were not used in this study, the low degree sectoral coefficients are believed to be slightly degraded compared to other solutions. The conventional GRACE/GRACE-FO temporal gravity solutions are at monthly sampling, which cannot easily be used to study sub-monthly mass transport events. However, the satellite ground track coverage varies from time to time. For the denser coverage time, a sub-monthly temporal resolution could be reached. A shorter solution data span, less than half of the nominal monthly data span, would enable observing signals which propagates quicker than a month. I employed the improved acceleration approach developed in this study to estimate solutions for every 13 days with one day sliding windows, which gives a daily sampling rate. The daily mass anomalies estimated from these solutions are shown to have a high correlation with the Morakot Typhoon (2009) induced precipitation evolutions (CC=0.87). It is shown that GRACE data is able to monitor the Morakot Typhoon induced massive rainfall during its landfall over Taiwan, which lasted only several days, though left a vast destruction on human lives and properties. In addition to the conventional spherical harmonic solutions, the GRACE/GRACE-FO Data Centers also deliver alternative data products called the “mascon solution”. Constraints are applied during the inversion so that it is free from the conventional GRACE post-processing. This advantage makes it a better candidate for coastal sediment deposition studies. Here, I used the University of Texas Center for Space Research (CSR) RL06 mascon data product to quantify the sediment deposition in the Bay of Bengal. By subtracting the Glacial Isostatic Adjustment (GIA) forward model predicted mass anomalies, ocean mass anomalies and the early Holocene Sediment Isostatic Adjustment (SIA) forward model predicted mass anomalies from the total mass change observed by GRACE (2002-2017), I obtained the mass anomalies estimation induced by the sediment discharge and transport in the Bay area. The corresponding sediment deposition rate estimate is 0.5± 0.2 Gt/yr, which is only half of the Brahmaputra river annual sediment discharge. This study also suggested the current SIA model tended to underestimate the SIA induced subsidence approximately by a factor of 2. In conclusion, the gravity solutions estimated from Swarm GPS tracking data using the modified decorrelation acceleration approach are capable to capture temporal gravity signals up to around degree 13. The Swarm-only solutions are shown to be able to fill the data gap between GRACE and GRACE-FO over West Antarctica and directly observe a fast mass loss episode. For GRACE and GRACE-FO, the improved acceleration approach has estimated the in-situ LOSGD with a high quality as indicated by the high correlation (CC=0.96) with L2 product predicted values and the monthly gravity solutions estimated from LOSGD have a good to excellent agreement with the official L2 products. The resulting GRACE daily sampled 13-day gravity solutions are capable to observe and quantify the evolution of an example abrupt weather episode, the landfall of the 2009 Morakot Typhoon over Taiwan. The demonstration of this novel monitoring of cyclone, for the first time, allows feasibility of using gravimetry data for possible disaster management.

Download or read book Remote Sensing by Satellite Gravimetry written by Thomas Gruber and published by MDPI. This book was released on 2021-01-19 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last two decades, satellite gravimetry has become a new remote sensing technique that provides a detailed global picture of the physical structure of the Earth. With the CHAMP, GRACE, GOCE and GRACE Follow-On missions, mass distribution and mass transport in the Earth system can be systematically observed and monitored from space. A wide range of Earth science disciplines benefit from these data, enabling improvements in applied models, providing new insights into Earth system processes (e.g., monitoring the global water cycle, ice sheet and glacier melting or sea-level rise) or establishing new operational services. Long time series of mass transport data are needed to disentangle anthropogenic and natural sources of climate change impacts on the Earth system. In order to secure sustained observations on a long-term basis, space agencies and the Earth science community are currently planning future satellite gravimetry mission concepts to enable higher accuracy and better spatial and temporal resolution. This Special Issue provides examples of recent improvements in gravity observation techniques and data processing and analysis, applications in the fields of hydrology, glaciology and solid Earth based on satellite gravimetry data, as well as concepts of future satellite constellations for monitoring mass transport in the Earth system.