scholarly journals Evaluation of using digital gravity field models for zoning map creation

2018 ◽  
Vol 1 ◽  
pp. 1-6
Author(s):  
Dmitry Loginov
Keyword(s):  
Gravity Field ◽  
Open Data ◽  
Software Systems ◽  
Digital Models ◽  
Geophysical Field ◽  
Noise Component ◽  
Gravity Field Model ◽  
The Creation ◽  
Models Of Gravity ◽  
Gravity Field Models

At the present time the digital cartographic models of geophysical fields are taking a special significance into geo-physical mapping. One of the important directions to their application is the creation of zoning maps, which allow taking into account the morphology of geophysical field in the implementation automated choice of contour intervals. The purpose of this work is the comparative evaluation of various digital models in the creation of integrated gravity field zoning map. For comparison were chosen the digital model of gravity field of Russia, created by the analog map with scale of 1 : 2 500 000, and the open global model of gravity field of the Earth – WGM2012. As a result of experimental works the four integrated gravity field zoning maps were obtained with using raw and processed data on each gravity field model. The study demonstrates the possibility of open data use to create integrated zoning maps with the condition to eliminate noise component of model by processing in specialized software systems. In this case, for solving problem of contour intervals automated choice the open digital models aren’t inferior to regional models of gravity field, created for individual countries. This fact allows asserting about universality and independence of integrated zoning maps creation regardless of detail of a digital cartographic model of geo-physical fields.

Using the Digital Models of Gravity Anomalies for Zoning of the Earth’s Gravity Field

2018 ◽  
Vol 54 (6) ◽  
pp. 964-970
Author(s):  
V. N. Koneshov ◽  
S. A. Krylov ◽  
D. S. Loginov ◽  
V. B. Nepoklonov
Keyword(s):  
Gravity Field ◽  
Gravity Anomalies ◽  
Digital Models ◽  
Earth’S Gravity Field ◽  
Models Of Gravity

Simulated experiment of recovering gravity field from the observations of satellite’s frequency signal

2020 ◽  
Author(s):  
Xinyu Xu ◽  
Ziyu Shen ◽  
Wenbin Shen ◽  
Yongqi Zhao
Keyword(s):  
Gravity Field ◽  
Field Model ◽  
Reference Model ◽  
Satellite Orbit ◽  
The Other ◽  
Frequency Signal ◽  
Gravity Field Model ◽  
Simulated Experiment ◽  
The One ◽  
Gravity Field Models

<p><span>Recovering the gravity field with the satellite’s frequency signal might be an alternative measuring mode in the future when the accuracy of the onboard clock was good enough. On the one hand, we analyze the performance of recovering gravity field model from the gravitational potentials with different accuracies on different satellite altitudes (from 200 km to 350 km) based on semi-analytical (SA) method. On the other hand, we analyze the performance based on the numerical analysis. First, the gravitational potentials along the satellite orbit are computed from the clock observations based on the method of satellite’s frequency signal with the accuracies of 10<sup>-16</sup> and 10<sup>-18</sup>s. Then, based on the derived gravitational potentials, we recovered the gravity field models up to degree and order 200 (corresponding to 100 km spatial resolution). At last, the errors of recovered models are validated by comparing with the reference model.</span></p>

scholarly journals Effects of New Level-1B Data on GRACE Temporal Gravity Field Models and Precise Orbit Determination Solutions

2021 ◽  
Vol 13 (20) ◽  
pp. 4119
Author(s):  
Nannan Guo ◽  
Xuhua Zhou ◽  
Kai Li
Keyword(s):  
Gravity Field ◽  
Orbit Determination ◽  
Field Model ◽  
Precise Orbit Determination ◽  
Satellite Orbit ◽  
Data Types ◽  
Gravity Field Model ◽  
Precise Orbit ◽  
Temporal Gravity ◽  
Gravity Field Models

The quality of Gravity Recovery and Climate Experiment (GRACE) observation is the prerequisite for obtaining the high-precision GRACE temporal gravity field model. To study the influence of new-generation GRACE Level-1B Release 03 (RL03) data and the new atmosphere and ocean de-aliasing (AOD1B) products on recovering temporal gravity field models and precise orbit determination (POD) solutions, we combined the global positioning system and K-band ranging-rate (KBRR) observations of GRACE satellites to estimate the effect of different data types on these solutions. The POD and monthly gravity field solutions are obtained from 2005 to 2010 by SHORDE software developed by the Shanghai Astronomical Observatory. The post-fit residuals of the KBRR data were decreased by approximately 10%, the precision of three-direction positions of the GRACE POD was improved by approximately 5%, and the signal-to-noise ratio of the monthly gravity field model was enhanced. The improvements in the new release of monthly gravity field model and POD solutions can be attributed to the enhanced Level-1B KBRR data and the AOD1B model. These improvements were primarily due to the enhanced of KBRR data; the effect of the AOD1B model was not significant. The results also showed that KBRR data slightly improve the satellite orbit precision, and obviously enhance the precision of the gravity field model.

scholarly journals An alternative method to improve gravity field models by incorporating GOCE gradient data

2018 ◽  
Vol 22 (3) ◽  
pp. 187-193 ◽  
Author(s):  
Xiaoyun Wan ◽  
Jiangjun Ran
Keyword(s):  
Gravity Field ◽  
Ocean Circulation ◽  
Field Model ◽  
Direct Method ◽  
European Space Agency ◽  
Gravity Field Model ◽  
Alternative Method ◽  
Space Agency ◽  
Gravitational Model ◽  
Gravity Field Models

The aim of this paper is to present an alternative method that can be used to improve existing gravity field models via the application of gradient data from Gravity field and Ocean Circulation Explorer (GOCE). First, the proposed algorithm used to construct the observation equation is presented. Then methods for noise processing in both time and space domains aimed at reducing noises are introduced. As an example, the European Improved Gravity model of the Earth by New techniques (EIGEN5C) is modified with gradient observations over the whole lifetime of the GOCE, leading to a new gravity field model named as EGMGOCE (Earth Gravitational Model of GOCE). The results show that the cumulative geoid difference between EGMGOCE and EGM08 is reduced by 4 centimeters compared with that between EIGEN5C and Earth Gravitational Model 2008 (EGM08) up to 200 degrees. The large geoid differences between EGMGOCE and EIGEN5C mainly exist in Africa, South America, Antarctica and Himalaya, which indicates the contribution from GOCE. Compared to the newest GOCE gravity field model resolved by direct method from European Space Agency (ESA), the cumulative geoid difference is reduced by 7 centimeters up to 200 degrees. 

scholarly journals Gravity Field Model Determination Based on GOCE Satellite Point-Wise Accelerations Estimated from Onboard Carrier Phase Observations

2019 ◽  
Vol 11 (12) ◽  
pp. 1420
Author(s):  
Tangting Wu ◽  
Jiancheng Li ◽  
Xinyu Xu ◽  
Hui Wei ◽  
Kaifa Kuang ◽  
...  
Keyword(s):  
Gravity Field ◽  
Carrier Phase ◽  
Field Model ◽  
Satellite Gravity ◽  
Gravity Field Model ◽  
Differentiation Method ◽  
Phase Differentiation ◽  
Satellite Accelerations ◽  
Gravity Field Models ◽  
Goce Satellite

GPS-based, satellite-to-satellite tracking observations have been extensively used to elaborate the long-scale features of the Earth’s gravity field from dedicated satellite gravity missions. We proposed compiling a satellite gravity field model from Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite accelerations directly estimated from the onboard GPS data using the point-wise acceleration approach, known as the carrier phase differentiation method. First, we composed the phase accelerations from the onboard carrier phase observations based on the sixth-order seven-point differentiator, which can eliminate the carrier phase ambiguity for Low Earth Orbiter (LEO). Next, the three-dimensional (3D) accelerations of the GOCE satellite were estimated from the derived phase accelerations as well as GPS satellite ephemeris and precise clock products. Finally, a global gravity field model up to the degree and order (d/o) 130 was compiled from the 71 days and nearly 2.5 years of 3D satellite accelerations. We also recovered three gravity field models up to d/o 130 from the accelerations derived by differentiating the kinematic orbits of European Space Agency (ESA), Graz, and School of Geodesy and Geomatics (SGG), which was the orbit differentiation method. We analyzed the accuracies of the derived accelerations and the recovered gravity field models based on the carrier phase differentiation method and orbit differentiation method in time, frequency, and spatial domain. The results showed that the carrier phase derived acceleration observations had better accuracy than those derived from kinematic orbits. The accuracy of the recovered gravity field model based on the carrier phase differentiation method using 2.5 years observations was higher than that of the orbit differentiation solutions for degrees greater than 70, and worse than Graz-orbit solution for degrees less than 70. The cumulative geoid height errors of carrier phase, ESA-orbit, and Graz-orbit solutions up to degree and order 130 were 17.70cm, 21.43 cm, and 22.11 cm, respectively.

scholarly journals Joint analysis of selected GRACE monthly spherical harmonic solutions and monthly MASCON solutions

2021 ◽  
Vol 51 (1) ◽  
pp. 47-61
Author(s):  
Adam NOVÁK ◽  
Juraj JANÁK ◽  
Barbora KOREKÁČOVÁ
Keyword(s):  
Gravity Field ◽  
Spherical Harmonic ◽  
Statistical Significance ◽  
Detailed Comparison ◽  
Joint Analysis ◽  
Satellite Mission ◽  
Science Data ◽  
Gravity Field Model ◽  
Global Gravity ◽  
Gravity Field Models

Study presented in this paper is focused on comparison and statistical assessment of differences between the selected Level 2 products of the satellite mission Gravity Recovery and Climate Experiment (GRACE). Global monthly gravity field models in terms of spherical harmonic coefficients produced by three institutes of GRACE Science Data System are compared with the partially independent MASCON global gravity field model. Detailed comparison and statistical analysis of differences is performed in 5 selected river basins: Amazon, Congo, Danube, Yenisei and Lena. For each spherical harmonic solution, 8 different filtrations available at International Center for Global Gravity Field Models (ICGEM) are tested over the time span from April 2002 to July 2016. Fischer test at two significance levels 10% and 5% has been performed in order to qualify the statistical significance between the particular solutions.

scholarly journals Sensitivity of Lageos Orbits to Global Gravity Field Models

2012 ◽  
Vol 47 (2) ◽  
pp. 47-65 ◽  
Author(s):  
K. Sośnica ◽  
D. Thaller ◽  
A. Jäggi ◽  
R. Dach ◽  
G. Beutler
Keyword(s):  
Gravity Field ◽  
Orbit Determination ◽  
Measurement Techniques ◽  
Precise Orbit Determination ◽  
Satellite Orbits ◽  
Gravity Field Model ◽  
Global Gravity ◽  
The Impact ◽  
Gravity Field Models

Sensitivity of Lageos Orbits to Global Gravity Field ModelsPrecise orbit determination is an essential task when analyzing SLR data. The quality of the satellite orbits strongly depends on the models used for dynamic orbit determination. The global gravity field model used is one of the crucial elements, which has a significant influence on the satellite orbit and its accuracy. We study the impact of different gravity field models on the determination of the LAGEOS-1 and -2 orbits for data of the year 2008. Eleven gravity field models are compared, namely JGM3 and EGM96 based mainly on SLR, terrestrial and altimetry data, AIUB-CHAMP03S based uniquely on GPS-measurements made by CHAMP, AIUB-GRACE03S, ITG-GRACE2010 based on GRACE data, and the combined gravity field models based on different measurement techniques, such as EGM2008, EIGEN-GL04C, EIGEN51C, GOCO02S, GO-CONS-2-DIR-R2, AIUB-SST. The gravity field models are validated using the RMS of the observation residuals of 7-day LAGEOS solutions. The study reveals that GRACE-based models have the smallest RMS values (i.e., about 7.15 mm), despite the fact that no SLR data were used to determine them. The coefficient C20is not always well estimated in GRACE-only models. There is a significant improvement of the gravity field models based on CHAMP, GRACE and GOCE w.r.t. models of the pre-CHAMP era. The LAGEOS orbits are particularly sensitive to the long wavelength part of the gravity fields. Differences of the estimated orbits due to different gravity field models are noticeable up to degree and order of about 30. The RMS of residuals improves from about 40 mm for degree 8, to about 7 mm for the solutions up to degrees 14 and higher. The quality of the predicted orbits is studied, as well.

Application of ultra‐precise GRACE Follow-On LRI measurements for validation of the state-of-the-art static gravity field models and examination of sub-monthly time-variable gravity signals

2020 ◽  
Author(s):  
Khosro Ghobadi Far ◽  
Shin-Chan Han ◽  
Jeanne Sauber ◽  
Richard Ray ◽  
Christopher M. McCullough ◽  
...  
Keyword(s):  
Gravity Field ◽  
High Frequency ◽  
State Of The Art ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
The State ◽  
Gravity Change ◽  
Gravity Field Model ◽  
Gravity Field Models

<p>The test Laser ranging interferometer (LRI) on the GRACE Follow-On satellites provides complementary inter-satellite ranging measurements to the baseline K-band microwave ranging (KBR) system that can be used to examine standard, and create novel, GRACE-FO data products.  We first calculated the KBR and LRI inter-satellite ranging residuals using dynamic orbits computed from non-gravitational accelerations, a static gravity field model and other background geophysical models like ocean tides. To accurately quantify the improvement by LRI, we directly examined the inter-satellite ranging residuals in the time and frequency domains. The frequency-domain analysis reveals that LRI enhances the accuracy of gravity measurements by ~1 order of magnitude over 60-200 CPR (10-37 mHz) frequencies with the signal dominated by static gravity field of the Earth. The time-domain analysis shows that LRI is capable of detecting static gravity signals as small as a few 0.1 nm/s<sup>2</sup> in 100-200 CPR frequency band. We made use of such LRI data acquired in 2019 to validate the state-of-the-art gravity field models GGM05S, GGM05C, GOCE-TIM-R6e, EIGEN-6C4, ITSG-Grace2018s and GOCO06s. We found that LRI data can identify subtle un-/mis-modeled static gravity signals in these models in the spectral as well as spatial domains, and thus, suggest how the next generation of gravity field models could be improved. We also examined the high‐frequency (sub-monthly) variations of the Argentine Gyre using LRI measurements along with satellite altimetry data. Through comparison of measured gravity change by LRI with synthetic gravity change from altimetry sea surface data (evaluated at GRACE Follow-On altitude), we clearly demonstrate how the high-frequency Argentine Gyre signal is fully captured by instantaneous LRI measurements by individual data arcs, but not in the monthly mean Level-2 data. Such along-orbit analyses of LRI data could be employed for, among others, validation of high-frequency non-tidal ocean models used in GRACE and GRACE Follow-On de-aliasing products.</p> <p> </p>

MASCON versus spherical harmonic solutions to global monthly time varying gravity field

2020 ◽  
Author(s):  
Juraj Janák ◽  
Adam Novák ◽  
Barbora Korekáčová
Keyword(s):  
Gravity Field ◽  
Spherical Harmonic ◽  
Polar Region ◽  
Field Model ◽  
River Basins ◽  
Spherical Harmonic Analysis ◽  
Time Varying ◽  
Gravity Field Model ◽  
Gravity Field Models ◽  
Research Centres

<p>Satellite missions Gravity Field and Climate Experiment (GRACE) and its successor (GRACE-FO) plays very important role in nowadays research in geodesy, geophysics, hydrology, oceanography, glaciology and climatology. Various research centres adopted different procedures for processing the GRACE/GRACE-FO measurements in order to get the main final product – the global monthly gravity field model. Until now there have been developed and published two fundamentally different approaches to this problem. The first is well-known approach of spherical harmonic analysis and the second is more recent and more direct approach called in literature MASCON (Mass Concentration). The purpose of this contribution is to compare existing MASCON global monthly gravity field models with the selected models based on spherical harmonic approach. Comparison is performed in selected river basins and also in selected polar region. Chosen river basins differ both in size and seasonal changes of continental water storage to cover more situations. Comparison of different filtered versions of spherical harmonic solutions (DDK1 – DDK7) with MASCON solution is also performed in one of the analysed river basins. Differences are analysed and advantages and drawbacks of two approaches and of particular models are discussed.</p>

scholarly journals Validation of GOCE global gravity field models using terrestrial gravity data in Norway

2012 ◽  
Vol 2 (2) ◽  
pp. 134-143 ◽  
Author(s):  
M. Šprlák ◽  
C. Gerlach ◽  
B. Pettersen
Keyword(s):  
Harmonic Analysis ◽  
Gravity Field ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Gravity Field Model ◽  
Terrestrial Gravity ◽  
Free Air ◽  
Global Gravity ◽  
Free Air Gravity ◽  
Gravity Field Models

Validation of GOCE global gravity field models using terrestrial gravity data in NorwayThe GOCE (Gravity field and steady-state Ocean Circulation Explorer) satellite gravity gradiometry mission maps the Earth's gravity field. Harmonic analysis of GOCE observations provides a global gravity field model (GGFM). Three theoretical strategies, namely the direct, the space-wise and the time-wise approach, have been proposed for GOCE harmonic analysis. Based on these three methods, several GGFMs have been provided to the user community by ESA. Thereby different releases are derived from different periods of GOCE observations and some of the models are based on combinations with other sources of gravity field information. Due to the multitude of GOCE GGFMs, validation against independent data is a crucial task for the quality description of the different models.In this study, GOCE GGFMs from three releases are validated with respect to terrestrial free-air gravity anomalies in Norway. The spectral enhancement method is applied to avoid spectral inconsistency between the terrestrial and the GOCE free-air gravity anomalies.The results indicate that the time-wise approach is a reliable harmonic analysis procedure in all three releases of GOCE models. The space-wise approach, available in two releases, provides similar results as the time-wise approach. The direct approach seems to be highly affected by a-priori information.

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