scholarly journals High-frequency analysis of Earth gravity field models based on terrestrial gravity and GPS/levelling data: a case study in Greece

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
T. D. Papanikolaou ◽  
N. Papadopoulos
Keyword(s):  
Gravity Field ◽  
Spherical Harmonic ◽  
Gravity Models ◽  
Earth Gravity Field ◽  
Earth Gravity ◽  
Gravity Field Recovery ◽  
High Degree ◽  
Spherical Harmonic Synthesis ◽  
Gravity Field Models ◽  
Terrestrial Data

AbstractThe present study aims at the validation of global gravity field models through numerical investigation in gravity field functionals based on spherical harmonic synthesis of the geopotential models and the analysis of terrestrial data. We examine gravity models produced according to the latest approaches for gravity field recovery based on the principles of the Gravity field and steadystate Ocean Circulation Explorer (GOCE) and Gravity Recovery And Climate Experiment (GRACE) satellite missions. Furthermore, we evaluate the overall spectrum of the ultra-high degree combined gravity models EGM2008 and EIGEN-6C3stat. The terrestrial data consist of gravity and collocated GPS/levelling data in the overall Hellenic region. The software presented here implements the algorithm of spherical harmonic synthesis in a degree-wise cumulative sense. This approach may quantify the bandlimited performance of the individual models by monitoring the degree-wise computed functionals against the terrestrial data. The degree-wise analysis performed yields insight in the short-wavelengths of the Earth gravity field as these are expressed by the high degree harmonics.

scholarly journals GOCE-Derived Coseismic Gravity Gradient Changes Caused by the 2011 Tohoku-Oki Earthquake

2019 ◽  
Vol 11 (11) ◽  
pp. 1295
Author(s):  
Xinyu Xu ◽  
Hao Ding ◽  
Yongqi Zhao ◽  
Jin Li ◽  
Minzhang Hu
Keyword(s):  
Gravity Field ◽  
Ocean Circulation ◽  
Spherical Harmonic ◽  
Least Squares Method ◽  
Time Variable ◽  
Gravity Models ◽  
Gravity Gradient ◽  
Gravity Field Recovery ◽  
Before And After ◽  
Gravity Field Models

In contrast to most of the coseismic gravity change studies, which are generally based on data from the Gravity field Recovery and Climate Experiment (GRACE) satellite mission, we use observations from the Gravity field and steady-state Ocean Circulation Explorer (GOCE) Satellite Gravity Gradient (SGG) mission to estimate the coseismic gravity and gravity gradient changes caused by the 2011 Tohoku-Oki Mw 9.0 earthquake. We first construct two global gravity field models up to degree and order 220, before and after the earthquake, based on the least-squares method, with a bandpass Auto Regression Moving Average (ARMA) filter applied to the SGG data along the orbit. In addition, to reduce the influences of colored noise in the SGG data and the polar gap problem on the recovered model, we propose a tailored spherical harmonic (TSH) approach, which only uses the spherical harmonic (SH) coefficients with the degree range 30–95 to compute the coseismic gravity changes in the spatial domain. Then, both the results from the GOCE observations and the GRACE temporal gravity field models (with the same TSH degrees and orders) are simultaneously compared with the forward-modeled signals that are estimated based on the fault slip model of the earthquake event. Although there are considerable misfits between GOCE-derived and modeled gravity gradient changes (ΔVxx, ΔVyy, ΔVzz, and ΔVxz), we find analogous spatial patterns and a significant change (greater than 3σ) in gravity gradients before and after the earthquake. Moreover, we estimate the radial gravity gradient changes from the GOCE-derived monthly time-variable gravity field models before and after the earthquake, whose amplitudes are at a level over three times that of their corresponding uncertainties, and are thus significant. Additionally, the results show that the recovered coseismic gravity signals in the west-to-east direction from GOCE are closer to the modeled signals than those from GRACE in the TSH degree range 30–95. This indicates that the GOCE-derived gravity models might be used as additional observations to infer/explain some time-variable geophysical signals of interest.

Analyzing spectral characteristics of the global Earth gravity field models obtained from the CHAMP, GRACE and GOCE space missions

2015 ◽  
Vol 6 (2) ◽  
pp. 101-108 ◽  
Author(s):  
A. P. Karpik ◽  
V. F. Kanushin ◽  
I. G. Ganagina ◽  
D. N. Goldobin ◽  
E. M. Mazurova
Keyword(s):  
Gravity Field ◽  
Spectral Characteristics ◽  
Space Missions ◽  
Earth Gravity Field ◽  
Earth Gravity ◽  
Gravity Field Models

scholarly journals An Assessment of the GOCE High-Level Processing Facility (HPF) Released Global Geopotential Models with Regional Test Results in Turkey

2020 ◽  
Vol 12 (3) ◽  
pp. 586 ◽  
Author(s):  
Bihter Erol ◽  
Mustafa Serkan Işık ◽  
Serdar Erol
Keyword(s):  
Gravity Field ◽  
Numerical Test ◽  
Geopotential Model ◽  
Test Results ◽  
Earth Gravity Field ◽  
Earth Gravity ◽  
Geopotential Models ◽  
Processing Facility ◽  
High Level ◽  
Gravity Field Models

The launch of dedicated satellite missions at the beginning of the 2000s led to significant improvement in the determination of Earth gravity field models. As a consequence of this progress, both the accuracies and the spatial resolutions of the global geopotential models increased. However, the spectral behaviors and the accuracies of the released models vary mainly depending on their computation strategies. These strategies are briefly explained in this article. Comprehensive quality assessment of the gravity field models by means of spectral and statistical analyses provides a comparison of the gravity field mapping accuracies of these models, as well as providing an understanding of their progress. The practical benefit of these assessments by means of choosing an optimal model with the highest accuracy and best resolution for a specific application is obvious for a broad range of geoscience applications, including geodesy and geophysics, that employ Earth gravity field parameters in their studies. From this perspective, this study aims to evaluate the GOCE High-Level Processing Facility geopotential models including recently published sixth releases using different validation methods recommended in the literature, and investigate their performances comparatively and in addition to some other models, such as GOCO05S, GOGRA04S and EGM2008. In addition to the validation statistics from various countries, the study specifically emphasizes the numerical test results in Turkey. It is concluded that the performance improves from the first generation RL01 models toward the final RL05 models, which were based on the entire mission data. This outcome was confirmed when the releases of different computation approaches were considered. The accuracies of the RL05 models were found to be similar to GOCO05S, GOGRA04S and even to RL06 versions but better than EGM2008, in their maximum expansion degrees. Regarding the results obtained from these tests using the GPS/leveling observations in Turkey, the contribution of the GOCE data to the models was significant, especially between the expansion degrees of 100 and 250. In the study, the tested geopotential models were also considered for detailed geoid modeling using the remove-compute-restore method. It was found that the best-fitting geopotential model with its optimal expansion degree (please see the definition of optimal degree in the article) improved the high-frequency regional geoid model accuracy by almost 15%.

- Aristoteles- Description Of The Earth Gravity Field Recovery Mission

2005 ◽  
Author(s):  
R. Benz ◽  
M. Langemann ◽  
M. Gramolla ◽  
G. Mecke
Keyword(s):  
Gravity Field ◽  
Earth Gravity Field ◽  
Earth Gravity ◽  
Gravity Field Recovery ◽  
The Earth

Are higher degree even zonals really harmful for the LARES/LAGEOS frame-dragging experiment?

2012 ◽  
Vol 90 (9) ◽  
pp. 883-888 ◽  
Author(s):  
G. Renzetti
Keyword(s):  
Gravity Field ◽  
Spherical Harmonics ◽  
Sufficient Accuracy ◽  
Gravity Models ◽  
Frame Dragging ◽  
Earth Gravity Field ◽  
Earth Gravity ◽  
The Earth ◽  
Earth Gravity Models ◽  
Low Altitude

The low-altitude effects of LARES are examined to determined how they can impact the outcome of the hoped 1% frame-dragging measurement in the LARES–LAGEOS experiment. This analysis, based on a different approach than other studies recently appearing in the literature, shows that the spherical harmonics of the Earth gravity field with degree ℓ > 60 may represent a threat because their errors map significantly into LARES orbital disturbances compared to frame-dragging. The GIF48 model was used. It is questionable whether future Earth gravity models by GRACE and GOCE will be of sufficient accuracy.

scholarly journals The Role Of High Degree Potential Coefficients And Satellite Altimeter Data In Gravity Field Aproximation In The Malaysian Region

1988 ◽  
pp. 1-9
Author(s):  
Majid Kadir
Keyword(s):  
Gravity Anomaly ◽  
Gravity Field ◽  
Peninsular Malaysia ◽  
Gravity Models ◽  
Altimeter Data ◽  
Satellite Altimeter ◽  
Earth Gravity ◽  
Gravity Measurements ◽  
High Degree ◽  
Satellite Altimeter Data

Earth Gravity models (OSU81, OSU86E,and F) defined by a set of high degree potential coefficients were used to generate the geopotential geoid in the Malaysian region. In the very near future, land gravity measurements can be carried out where the station positioning in the survey will be by Global Positioning System (GPS) operating in differential mode. In areas with scarce height benchmark, especially in the remote areas of Peninsular Malaysia, the geopotential geoid can be utilized in conjunction with the satellite derived ellipsoidal heights to yield the orthometric heights of the gravity stations. Satellite altimeter data has the ability to provide high frequency gravity field information in the surrounding marine areas. The method of gravity anomaly recovery in the Tioman test area was based on the theory of least squares collocation. Gravity anomaly maps derived from satellite altimeter data can be used to scan large off-shore areas for detecting density contrasts within the oceanic's outer crust, and thus providing an indirect indication of potential hydrocarbon deposits.

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