Regional gravity field recovery of the void areas using SGG-derived surface residual gravity disturbances based on least-squares collocation: a case study in Iran

2019 ◽  
Vol 164 ◽  
pp. 40-52
Author(s):  
S.A. Saadat ◽  
A. Safari ◽  
M. Pitoňák ◽  
M. Rexer
Keyword(s):  
Least Squares ◽  
Gravity Field ◽  
Least Squares Collocation ◽  
Residual Gravity ◽  
Gravity Field Recovery ◽  
Gravity Disturbances ◽  
Regional Gravity

scholarly journals Investigating the optimal integration of airborne, ship-borne, satellite and terrestrial gravity data for use in geoid determination

2021 ◽  
Author(s):  
◽  
Rachelle Winefield
Keyword(s):  
Least Squares ◽  
Gravity Field ◽  
Integration Method ◽  
Bouguer Anomaly ◽  
Least Squares Collocation ◽  
Integration Methods ◽  
Case Study Area ◽  
Gravity Observation ◽  
Gravity Map

<p>Each gravity observation technique has different parameters and contributes to different pieces of the gravity spectrum. This means that no one gravity dataset is able to model the Earth’s gravity field completely and the best gravity map is one derived from many sources. Therefore, one of the challenges in gravity field modelling is combining multiple types of heterogeneous gravity datasets.  The aim of this study is to determine the optimal method to produce a single gravity map of the Canterbury case study area, for the purposes of use in geoid modelling.  This objective is realised through the identification and application of a four-step integration process: purpose, data, combination and assessment. This includes the evaluation of three integration methods: natural neighbour, ordinary kriging and least squares collocation.  As geoid modelling requires the combination of gravity datasets collected at various altitudes, it is beneficial to be able to combine the dataset using an integration method which operates in a three-dimensional space. Of the three integration methods assessed, least squares collocation is the only integration method which is able to perform this type of reduction.  The resulting product is a Bouguer anomaly map of the Canterbury case study area, which combines satellite altimetry, terrestrial, ship-borne, airborne, and satellite gravimetry using least squares collocation.</p>

scholarly journals Investigating the optimal integration of airborne, ship-borne, satellite and terrestrial gravity data for use in geoid determination

2021 ◽  
Author(s):  
◽  
Rachelle Winefield
Keyword(s):  
Least Squares ◽  
Gravity Field ◽  
Integration Method ◽  
Bouguer Anomaly ◽  
Least Squares Collocation ◽  
Integration Methods ◽  
Case Study Area ◽  
Gravity Observation ◽  
Gravity Map

<p>Each gravity observation technique has different parameters and contributes to different pieces of the gravity spectrum. This means that no one gravity dataset is able to model the Earth’s gravity field completely and the best gravity map is one derived from many sources. Therefore, one of the challenges in gravity field modelling is combining multiple types of heterogeneous gravity datasets.  The aim of this study is to determine the optimal method to produce a single gravity map of the Canterbury case study area, for the purposes of use in geoid modelling.  This objective is realised through the identification and application of a four-step integration process: purpose, data, combination and assessment. This includes the evaluation of three integration methods: natural neighbour, ordinary kriging and least squares collocation.  As geoid modelling requires the combination of gravity datasets collected at various altitudes, it is beneficial to be able to combine the dataset using an integration method which operates in a three-dimensional space. Of the three integration methods assessed, least squares collocation is the only integration method which is able to perform this type of reduction.  The resulting product is a Bouguer anomaly map of the Canterbury case study area, which combines satellite altimetry, terrestrial, ship-borne, airborne, and satellite gravimetry using least squares collocation.</p>

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

&lt;p&gt;In the frame of the IAG Subcommission 2.4f &amp;#8220;Gravity and Geoid in Antarctica&amp;#8221; (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).&lt;/p&gt;&lt;p&gt;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).&lt;/p&gt;&lt;p&gt;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&amp;#8217;s interior (cf. the contribution of Schaller et al. in session G4.3).&lt;/p&gt;

An integrated geophysical approach for imaging subbasalt sedimentary basins: Case study of Jam River Basin, India

Geophysics ◽  
2007 ◽  
Vol 72 (6) ◽  
pp. B141-B147 ◽  
Author(s):  
V. Chakravarthi ◽  
G. B. K. Shankar ◽  
D. Muralidharan ◽  
T. Harinarayana ◽  
N. Sundararajan
Keyword(s):  
Gravity Field ◽  
River Basin ◽  
Gravity Data ◽  
Sedimentary Basins ◽  
Gravity Inversion ◽  
Data Points ◽  
3D Gravity ◽  
Regional Gravity ◽  
Godavari Basin

An integrated geophysical strategy comprising deep electrical resistivity and gravity data was devised to image subbasalt sedimentary basins. A 3D gravity inversion was used to determine the basement structure of the Permian sediments underlying the Cretaceous formation of the Jam River Basin in India. The thickness of the Cretaceous formation above the Permian sediments estimated from modeling 60 deep-electric-sounding data points agrees well with drilling information. The gravity effect of mass deficit between the Cretaceous and Permian formations was found using 3D forward modeling and subsequently removed from the Bouguer gravity anomaly along with the regional gravity field. The modified residual gravity field was then subjected to3D inversion to map the variations in depth of the basement beneath the Permian sediments. Inversion of gravity data resulted in two basement ridges, running almost east to west, dividing the basin into three independent depressions. It was found that the Katol and Kondhali faults were active even during post-Cretaceous time and were responsible for the development of the subsurface basement ridges in the basin. The inferred 3D basement configuration of the basin clearly brought out the listric nature of these two faults. Further, the extension of the Godavari Basin into the Deccan syneclise and the fact that the source-rock studies show the presence of hydrocarbons in the Sironcha block in the northern part of the Godavari Basin also shed some light on the hydrocarbon potential of the Jam River Basin.

THE USE OF CRACOVIAN COMPUTATION IN ESTIMATING THE REGIONAL GRAVITY

Geophysics ◽  
1959 ◽  
Vol 24 (3) ◽  
pp. 465-478 ◽  
Author(s):  
Zbigniew Fajklewicz
Keyword(s):  
Least Squares ◽  
Gravity Field ◽  
Gravity Anomalies ◽  
Second Order ◽  
Method Of Least Squares ◽  
Electronic Computers ◽  
Regional Gravity ◽  
Work Done ◽  
Very High ◽  
Digital Computers

The author uses the method of least squares in cracovian form and second order polynomials for estimating the regional gravity field. Expressions yielding the regional field are obtained very rapidly by using the inverse cracovians of the coefficients as given in the present paper, and there is no need of electronic digital computers for the computation. The equivalent of the entire work done by a computer of this kind in constructing the formula of the regional field, when effected by this method, takes no more than 20 minutes. The method is exemplified by the treatment of two gravity anomalies from the territory of Poland. The author stresses the fact that electronic computers adapted to the use of cracovians and characterized by a very high versatility may be applied in the method.

scholarly journals Multi-processing least squares collocation: Applications to gravity field analysis

2013 ◽  
Vol 3 (3) ◽  
Author(s):  
E. Kaas ◽  
B. Sørensen ◽  
C. C. Tscherning ◽  
M. Veicherts
Keyword(s):  
Least Squares ◽  
Gravity Field ◽  
Field Analysis ◽  
Least Squares Collocation
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