The Earth’s Gravity Field Components of the Differences Between Gravity Disturbances and Gravity Anomalies

2009 ◽  
pp. 155-159
Author(s):  
R Tenzer ◽  
A Ellmann ◽  
P Novák ◽  
P Vajda
Keyword(s):  
Gravity Field ◽  
Gravity Anomalies ◽  
Earth’S Gravity Field ◽  
Gravity Disturbances

scholarly journals COMPUTATION OF GRAVITY FIELD FUNCTIONALS WITH A LOCALIZED LEVEL ELLIPSOID

2021 ◽  
Vol 6 (24) ◽  
pp. 226-242
Author(s):  
Chivatsi Jonathan Nyoka ◽  
Ami Hassan Md Din ◽  
Muhammad Faiz Pa’suya
Keyword(s):  
Gravity Field ◽  
Spherical Harmonic ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Earth’S Gravity Field ◽  
Geopotential Models ◽  
Gravity Disturbances ◽  
Zero Degree ◽  
Equipotential Surfaces ◽  
Best Fit

The description of the earth’s gravity field is usually expressed in terms of spherical harmonic coefficients, derived from global geopotential models. These coefficients may be used to evaluate such quantities as geoid undulations, gravity anomalies, gravity disturbances, deflection of the vertical, etc. To accomplish this, a global reference normal ellipsoid, such as WGS84 and GRS80, is required to provide the computing reference surface. These global ellipsoids, however, may not always provide the best fit of the local geoid and may provide results that are aliased. In this study, a regional or localized geocentric level ellipsoid is used alongside the EGM2008 to compute gravity field functionals in the state of Johor. Residual gravity field quantities are then computed using GNSS-levelled and raw gravity data, and the results are compared with both the WGS84 and the GRS80 equipotential surfaces. It is demonstrated that regional level ellipsoids may be used to compute gravity field functionals with a better fit, provided the zero-degree spherical harmonic is considered. The resulting residual quantities are smaller when compared with those obtained with global ellipsoids. It is expected that when the remove-compute-restore method is employed with such residuals, the numerical quadrature of the Stoke’s integral may be evaluated on reduced gravity anomalies that are smoother compared to when global equipotential surfaces are used

Towards an updated, enhanced regional gravity field solution for Antarctica

2021 ◽  
Author(s):  
Mirko Scheinert ◽  
Philipp Zingerle ◽  
Theresa Schaller ◽  
Roland Pail ◽  
Martin Willberg
Keyword(s):  
Gravity Anomaly ◽  
Gravity Field ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Data Set ◽  
Gravity Field Model ◽  
Terrestrial Gravity ◽  
Field Solution ◽  
Gravity Disturbances ◽  
Regional Gravity

<p>In the frame of the IAG Subcommission 2.4f “Gravity and Geoid in Antarctica” (AntGG) a first Antarctic-wide grid of ground-based gravity anomalies was released in 2016 (Scheinert et al. 2016). That data set was provided with a grid space of 10 km and covered about 73% of the Antarctic continent. Since then a considerably amount of new data has been made available, mainly collected by means of airborne gravimetry. Regions which were formerly void of any terrestrial gravity observations and have now been surveyed include especially the polar data gap originating from GOCE satellite gravimetry. Thus, it is timely to come up with an updated and enhanced regional gravity field solution for Antarctica. For this, we aim to improve further aspects in comparison to the AntGG 2016 solution: The grid spacing will be enhanced to 5 km. Instead of providing gravity anomalies only for parts of Antarctica, now the entire continent should be covered. In addition to the gravity anomaly also a regional geoid solution should be provided along with further desirable functionals (e.g. gravity anomaly vs. disturbance, different height levels).</p><p>We will discuss the expanded AntGG data base which now includes terrestrial gravity data from Antarctic surveys conducted over the past 40 years. The methodology applied in the analysis is based on the remove-compute-restore technique. Here we utilize the newly developed combined spherical-harmonic gravity field model SATOP1 (Zingerle et al. 2019) which is based on the global satellite-only model GOCO05s and the high-resolution topographic model EARTH2014. We will demonstrate the feasibility to adequately reduce the original gravity data and, thus, to also cross-validate and evaluate the accuracy of the data especially where different data set overlap. For the compute step the recently developed partition-enhanced least-squares collocation (PE-LSC) has been used (Zingerle et al. 2021, in review; cf. the contribution of Zingerle et al. in the same session). This method allows to treat all data available in Antarctica in one single computation step in an efficient and fast way. Thus, it becomes feasible to iterate the computations within short time once any input data or parameters are changed, and to easily predict the desirable functionals also in regions void of terrestrial measurements as well as at any height level (e.g. gravity anomalies at the surface or gravity disturbances at constant height).</p><p>We will discuss the results and give an outlook on the data products which shall be finally provided to present the new regional gravity field solution for Antarctica. Furthermore, implications for further applications will be discussed e.g. with respect to geophysical modelling of the Earth’s interior (cf. the contribution of Schaller et al. in session G4.3).</p>

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

scholarly journals GRAVITY ANOMALY ASSESSMENT USING GGMS AND AIRBORNE GRAVITY DATA TOWARDS BATHYMETRY ESTIMATION

2016 ◽  
Vol XLII-4/W1 ◽  
pp. 287-297
Author(s):  
A. Tugi ◽  
A. H. M. Din ◽  
K. M. Omar ◽  
A. S. Mardi ◽  
Z. A. M. Som ◽  
...  
Keyword(s):  
Gravity Anomaly ◽  
Gravity Field ◽  
Ocean Circulation ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Airborne Gravity ◽  
Satellite Gravity ◽  
Earth’S Gravity Field ◽  
Explorer Mission ◽  
Satellite Gravity Missions

The Earth’s potential information is important for exploration of the Earth’s gravity field. The techniques of measuring the Earth’s gravity using the terrestrial and ship borne technique are time consuming and have limitation on the vast area. With the space-based measuring technique, these limitations can be overcome. The satellite gravity missions such as Challenging Mini-satellite Payload (CHAMP), Gravity Recovery and Climate Experiment (GRACE), and Gravity-Field and Steady-State Ocean Circulation Explorer Mission (GOCE) has introduced a better way in providing the information on the Earth’s gravity field. From these satellite gravity missions, the Global Geopotential Models (GGMs) has been produced from the spherical harmonics coefficient data type. The information of the gravity anomaly can be used to predict the bathymetry because the gravity anomaly and bathymetry have relationships between each other. There are many GGMs that have been published and each of the models gives a different value of the Earth’s gravity field information. Therefore, this study is conducted to assess the most reliable GGM for the Malaysian Seas. This study covered the area of the marine area on the South China Sea at Sabah extent. Seven GGMs have been selected from the three satellite gravity missions. The gravity anomalies derived from the GGMs are compared with the airborne gravity anomaly, in order to figure out the correlation (R<sup>2</sup>) and the root mean square error (RMSE) of the data. From these assessments, the most suitable GGMs for the study area is GOCE model, GO_CONS_GCF_2_TIMR4 with the R<sup>2</sup> and RMSE value of 0.7899 and 9.886 mGal, respectively. This selected model will be used in the estimating the bathymetry for Malaysian Seas in future.

scholarly journals Global atmospheric effects on the gravity field quantities

2009 ◽  
Vol 39 (3) ◽  
pp. 221-236 ◽  
Author(s):  
Robert Tenzer ◽  
Peter Vajda ◽  
Keyword(s):  
Density Distribution ◽  
Gravity Field ◽  
Gravity Anomalies ◽  
The United States ◽  
Lower Atmosphere ◽  
Atmospheric Effects ◽  
Atmospheric Density ◽  
Standard Atmosphere ◽  
Gravity Disturbances ◽  
United States Standard

Global atmospheric effects on the gravity field quantitiesWe compile the global maps of atmospheric effects on the gravity field quantities using the spherical harmonic representation of the gravitational field. A simple atmospheric density distribution is assumed within a lower atmosphere (< 6 km). Disregarding temporal and lateral atmospheric density variations, the radial atmospheric density model is defined as a function of the nominal atmospheric density at the sea level and the height. For elevations above 6 km, the atmospheric density distribution from the United States Standard Atmosphere 1976 is adopted. The 5 × 5 arc-min global elevation data from the ETOPO5 are used to generate the global elevation model coefficients. These coefficients (which represent the geometry of the lower bound of atmospheric masses) are utilized to compute the atmospheric effects with a spectral resolution complete to degree and order 180. The atmospheric effects on gravity disturbances, gravity anomalies and geoid undulations are evaluated globally on a 1 × 1 arc-deg grid.

Probing the Earth’s gravity field by means of satellite-to-satellite tracking

1977 ◽  
Vol 284 (1326) ◽  
pp. 475-483 ◽  
Keyword(s):  
Gravity Field ◽  
Signal To Noise Ratio ◽  
Gravity Anomalies ◽  
Small Variation ◽  
Satellite Tracking ◽  
Practical Advantage ◽  
Earth’S Gravity Field ◽  
Ground Station ◽  
Local Gravity ◽  
Range Rate

The idea of tracking one spacecraft from another grew out of some tracking studies performed early in the Apollo programme (1962-3). The main practical advantage of such a technique is that ( a ) contact time with a low orbiting spacecraft can be increased considerably (approximately 50 min v . 5 min for a single ground station); ( b ) the number of ground stations can be reduced; ( c ) the dependency on stations on foreign soil can almost be eliminated; and ( d ) detailed studies of spacecraft motions due to small variations in the Earth’s gravity field (anomalies) may be detectable. This paper describes specifically two satellite-to-satellite tracking (s. s. t.) tests, namely ( a ) the ATS-6/Geos-3 and ( b ) the ATS-6/Apollo-Soyuz experiment and some of the results obtained. The main purpose of these two experiments was first to track via ATS-6 the Geos-3 as well as the Apollo-Soyuz and to use these tracking data to determine ( a ) both orbits, that is, ATS-6, Geos-3 and/or the Apollo-Soyuz orbits at the same time; ( b ) each of these orbits alone, and ( c ) test the ATS-6/Geos-3 and /or Apollo-Soyuz s. s. t. link to study local gravity anomalies; and, second, to test communications, command and data transmission from the ground via ATS-6 to these spacecraft and back again to the ground (Rosman, N. G.). Most of the interesting data obtained to date originate from the Apollo-Soyuz geodynamics experiment. Thus, it will be discussed in some detail. Gravity anomalies of say 3-5 mGal (3-5 × 10 -5 m s -2 ) or larger having wavelength of 500-1000 km on the Earth’s surface are important for studies of the upper layers of the earth. Such anomalies were actually ‘seen’ for the first time from space as signatures in the form of very small variation (order of ~ 1 to 2 cm/s) in the range rate between ATS-6, Geos-3 and Apollo-Soyuz. Since the measured range noise turned out to be only 0.03- 0.05 cm/s on the average, these signatures were detected with an excellent signal-to-noise ratio. Orbit determination examples using s. s. t. data from ATS-6 and Geos-3 are also discussed in detail together with errors associated with the orbits of Geos-3. Further, signature studies and gravity anomaly detections with s. s. t. data will be shown and discussed in detail.

scholarly journals An Analysis of Choosing Gravity Anomalies for Solving Problems in Geodesy, Geophysics and Environmental Engineering

2020 ◽  
Author(s):  
Vytautas Puškorius ◽  
Eimuntas Paršeliūnas ◽  
Petras Petroškevičius ◽  
Romuald Obuchovski
Keyword(s):  
Gravity Field ◽  
Gravity Anomalies ◽  
Environmental Engineering ◽  
Correct Selection ◽  
Earth’S Gravity Field ◽  
The Earth ◽  
Pure Gravity ◽  
Geodynamic Processes ◽  
Selection Of

Gravity anomalies provide valuable information about the Earth‘s gravity field. They are used for solving various geophysical and geodetic tasks, mineral and oil exploration, geoid and quasi-geoid determination, geodynamic processes of Earth, determination of the orbits of various objects, moving in space around the Earth etc. The increasing accuracy of solving the above mentioned problems poses new requirements for the accuracy of the gravity anomalies. Increasing the accuracy of gravity anomalies can be achieved by gaining the accuracy of the gravimetric and geodetic measurements, and by improving the methodology of the anomalies detection. The modern gravimetric devices allow to measure the gravity with an accuracy of several microgals. Space geodetic systems allow to define the geodetic coordinates and ellipsoidal heights of gravimetric points within a centimeter accuracy. This opens up the new opportunities to calculate in practice both hybrid and pure gravity anomalies and to improve their accuracy. In this context, it is important to analyse the possibilities of detecting various gravity anomalies and to improve the methodology for detecting gravity anomalies. Also it is important the correct selection of the gravity anomalies for different geodetic, geophysical and environmental engineering tasks. The modern gravity field data of the territory of Lithuania are used for the research.

Theory of the earth's gravity field

1974 ◽  
Vol 10 (3) ◽  
pp. 237-238
Author(s):  
F. Morrison
Keyword(s):  
Gravity Field ◽  
Earth’S Gravity Field
Sign in / Sign up

Export Citation Format

Share Document