Domain Transformation, Boundary Problems and Optimization Concepts in the Combination of Terrestrial and Satellite Gravity Field Data

2009 ◽  
pp. 219-228 ◽  
Author(s):  
P Holota ◽  
O Nesvadba
Keyword(s):  
Gravity Field ◽  
Field Data ◽  
Satellite Gravity ◽  
Boundary Problems ◽  
Domain Transformation

Effect of Ocean Tide on Recovery of Satellite Gravity Field

2007 ◽  
Vol 50 (1) ◽  
pp. 116-123 ◽  
Author(s):  
Jiang-Cun ZHOU ◽  
He-Ping SUN
Keyword(s):  
Gravity Field ◽  
Ocean Tide ◽  
Satellite Gravity

Combining the deep Earth and lithospheric gravity field to study the density structure of the upper mantle

2021 ◽  
Author(s):  
Bart Root ◽  
Javier Fullea ◽  
Jörg Ebbing ◽  
Zdenek Martinec
Keyword(s):  
Gravity Field ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Field Data ◽  
Wavelength Region ◽  
Density Structure ◽  
Long Wavelength ◽  
Global Gravity ◽  
Deep Earth

<p>Global gravity field data obtained by dedicated satellite missions is used to study the density distribution of the lithosphere. Different multi-data joint inversions are using this dataset together with other geophysical data to determine the physical characteristics of the lithosphere. The gravitational signal from the deep Earth is usually removed by high-pass filtering of the model and data, or by appropriately selecting insensitive gravity components in the inversion. However, this will remove any long-wavelength signal inherent to lithosphere. A clear choice on the best-suited approach to remove the sub-lithospheric gravity signal is missing. </p><p>Another alternative is to forward model the gravitational signal of these deep situated mass anomalies and subtract it from the observed data, before the inversion. Global tomography provides shear-wave velocity distribution of the mantle, which can be transformed into density anomalies. There are difficulties in constructing a density model from this data. Tomography relies on regularisation which smoothens the image of the mantle anomalies. Also, the shear-wave anomalies need to be converted to density anomalies, with uncertain conversion factors related to temperature and composition. Understanding the sensitivity of these effects could help determining the interaction of the deep Earth and the lithosphere.</p><p>In our study the density anomalies of the mantle, as well as the effect of CMB undulations, are forward modelled into their gravitational potential field, such that they can be subtracted from gravity observations. The reduction in magnitude of the density anomalies due to the regularisation of the global tomography models is taken into account. The long-wavelength region of the density estimates is less affected by the regularisation and can be used to fix the mean conversion factor to transform shear wave velocity to density. We present different modelling approaches to add the remaining dynamic topography effect in lithosphere models. This results in new solutions of the density structure of the lithosphere that both explain seismic observations and gravimetric measurements. The introduction of these dynamic forces is a step forward in understanding how to properly use global gravity field data in joint inversions of lithosphere models.</p>

scholarly journals Accuracy Analysis of Gravity Field Changes from Grace RL06 and RL05 Data Compared to in Situ Gravimetric Measurements in the Context of Choosing Optimal Filtering Type

2020 ◽  
Vol 55 (3) ◽  
pp. 100-117
Author(s):  
Viktor Szabó ◽  
Dorota Marjańska
Keyword(s):  
Gravity Field ◽  
Ocean Circulation ◽  
Gravity Data ◽  
The Other ◽  
Subsurface Water ◽  
Satellite Gravity ◽  
Absolute Gravimetry ◽  
The Earth ◽  
Gravity Measurements ◽  
Gravity Recovery

AbstractGlobal satellite gravity measurements provide unique information regarding gravity field distribution and its variability on the Earth. The main cause of gravity changes is the mass transportation within the Earth, appearing as, e.g. dynamic fluctuations in hydrology, glaciology, oceanology, meteorology and the lithosphere. This phenomenon has become more comprehensible thanks to the dedicated gravimetric missions such as Gravity Recovery and Climate Experiment (GRACE), Challenging Minisatellite Payload (CHAMP) and Gravity Field and Steady-State Ocean Circulation Explorer (GOCE). From among these missions, GRACE seems to be the most dominating source of gravity data, sharing a unique set of observations from over 15 years. The results of this experiment are often of interest to geodesists and geophysicists due to its high compatibility with the other methods of gravity measurements, especially absolute gravimetry. Direct validation of gravity field solutions is crucial as it can provide conclusions concerning forecasts of subsurface water changes. The aim of this work is to present the issue of selection of filtration parameters for monthly gravity field solutions in RL06 and RL05 releases and then to compare them to a time series of absolute gravimetric data conducted in quasi-monthly measurements in Astro-Geodetic Observatory in Józefosław (Poland). The other purpose of this study is to estimate the accuracy of GRACE temporal solutions in comparison with absolute terrestrial gravimetry data and making an attempt to indicate the significance of differences between solutions using various types of filtration (DDK, Gaussian) from selected research centres.

THE USE OF POISSON’S RELATION FOR THE EXTRACTION OF PSEUDOTOTAL MAGNETIC FIELD INTENSITY FROM GRAVITY OBSERVATIONS

Geophysics ◽  
1971 ◽  
Vol 36 (3) ◽  
pp. 605-608 ◽  
Author(s):  
Edwin S. Robinson
Keyword(s):  
Magnetic Field ◽  
Gravity Field ◽  
Field Data ◽  
Field Potential ◽  
Geological Structure ◽  
Common Source ◽  
Uniform Density ◽  
Practical Applications ◽  
Uniform Magnetization ◽  
Gravity Fields

Investigation of geological structure by gravimetric and magnetic field surveys requires consideration of relationships between gravity anomaly and magnetic anomaly generating sources. The possibility of using Poisson’s Relation to examine magnetic and gravity fields related to a common source is intriguing. This relation is expressed as follows: [Formula: see text] (1) where A (x, y, z) is the magnetic field potential and U (x, y, z) is the gravity field potential at a point in space due to a source of uniform density ρ and uniform magnetization I in the direction α. This expression has been used to derive magnetic anomalies over idealized forms (Nettleton, 1940) and, by Baranov (1957), to extract pseudogravity fields from magnetic field data. The purpose of this paper is to develop an expression for extracting a pseudomagnetic field from gravity field data and to examine the practical applications of this expression.

Consistent quantification of the impact of key mission design parameters on the performance of next-generation gravity missions

2020 ◽  
Vol 221 (2) ◽  
pp. 1190-1210 ◽  
Author(s):  
Anna F Purkhauser ◽  
Christian Siemes ◽  
Roland Pail
Keyword(s):  
Gravity Field ◽  
Laser Interferometry ◽  
Limiting Factors ◽  
Mission Design ◽  
Design Parameters ◽  
Ocean Tide ◽  
Single Pair ◽  
Post Processing ◽  
Satellite Gravity ◽  
The Impact

SUMMARY The GRACE and GRACE-FO missions have been observing time variations of the Earth's gravity field for more than 15 yr. For a possible successor mission, the need to continue mass change observations have to be balanced with the ambition for monitoring capabilities with an enhanced spatial and temporal resolution that will enable improved scientific results and will serve operational services and applications. Various study groups performed individual simulations to analyse different aspects of possible NGGMs from a scientific and technical point of view. As these studies are not directly comparable due to different assumptions regarding mission design and instrumentation, the goal of this paper is to systematically analyse and quantify the key mission parameters (number of satellite pairs, orbit altitude, sensors) and the impact of various error sources (AO, OT models, post-processing) in a consistent simulation environment. Our study demonstrates that a single-pair mission with laser interferometry in a low orbit with a drag compensation system would be the only possibility within the single-pair options to increase the performance compared to the GRACE/GRACE-FO. Tailored post-processing is not able to achieve the same performance as a double-pair mission without post-processing. Also, such a mission concept does not solve the problems of temporal aliasing due to observation geometry. In contrast, double-pair concepts have the potential to retrieve the full AOHIS signal and in some cases even double the performance to the comparable single-pair scenario. When combining a double-pair with laser interferometry and an improved accelerometer, the sensor noise is, apart from the ocean tide modelling errors, one of the limiting factors. Therefore, the next big step for observing the gravity field globally with a satellite mission can only be taken by launching a double pair mission. With this quantification of key architecture features of a future satellite gravity mission, the study aims to improve the available information to allow for an informed decision making and give an indication of priority for the different mission concepts.

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